Applications for a DC Accurate Lowpass Switched-Capacitor Filter: AN20 Linear Technology Discusses principles of operation of LTC1062 and helpful hints for its application. Various application circuits are explained in detail with focus on how to cascade two LTC1062s and how to obtain notches. Noise and distortion performance are fully illustrated.
SSB AF Filter: This is a simple filter that restricts the LF response a little as well providing quite a heavy HF roll-off. The prototype has enhanced a Yaesu FT101B that was only fitted with an AM IF filter. The IC is an LM358. (added 02/05)
Unique Applications for the LTC1062 Lowpass Filter: AN24 Linear Technology Highlights the LTC1062 as a lowpass filter in a phase lock loop. Describes how the loop's bandwidth can be increased and the VCO output jitter reduced when the LTC1062 is the loop filter. Compares it with a passive RC loop filter. Also discussed is the use of LTC1062 as simple bandpass and band stop filter.
Single Resistor Tunes Lowpass Filter: 08/21/03 EDN Design Ideas / (added 12/04) Any tunable, second-order, active RC-filter section requires at least two thoroughly matched variable resistors. But the lowpass implementation in Figure 1 provides for wide-range cutoff-frequency control using only a single variable resistor, R. In addition to the resistor, this filter comprises an operational amplifier, IC2, which serves as a unity-gain buffer; two capacitors, C1 and C2; ......
Lowpass Filter Discriminates Step Input from Noise: 09/18/03 EDN Design Ideas / (added 12/04) Numerous applications exist in industry, particularly with control systems, in which it is desirable to remove all but the lowest frequency components from a signal to effectively yield a dc voltage. This voltage may, for example, serve as a setpoint to a PID controller in a process-control or an HVAC application, in which the cable that is carrying the analog signal is exposed to a wide spectra......
Ultrasonic Switch: Circuit of a new type of remote control switch is described here. This circuit functions with inaudible (ultrasonic) sound. Sound of frequency up to 20 kHz is audible to human beings. The sound of frequency above 20 kHz is called ultrasonic sound. The circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit too comprises a mini transmitter and a receiver circuit. Transmitter generates ultrasonic…. (added 10/05)
Highpass Filters Use Modified Equalelement Design: 05/24/01 EDN-Design Ideas / (added 5/03) Using a modified equal-element design for a lumped-circuit lowpass filter has several advantages over the well-known equal-element design (Reference 1 and Reference 2). The modified design exhibits superior passband performance with only modest degradation of stopband selectivity. Moreover, the ....
Lowpass Filter has Improved Step Response: 02/19/04 EDN Design Ideas / (added 12/04) A common problem that arises when you design lowpass filters for signal conditioning is the filters' effect on the system's time-domain response. Because pushing the cutoff frequency lower slows the step response, the system may fail to recognize significant changes within a reasonable amount of time....
Precision Level Shifter has Excellent CMRR: 04/15/04 EDN Design Ideas / (added 1/05) Most designers make level shifters with op amps and 1%-tolerance discrete resistors. Discrete-resistor mismatching limits the op amp's CMMR (common-mode rejection ratio) to 40 dB, so you cannot use op amps in circuits that require high CMRR. Differential amplifiers contain precision matched internal resistors, so ICs such as the INA133 can readily achieve CMRRs of approximately 90 dB....
Model Fixed Point DSP Arithmetic in C: 03/18/99 EDN-Design Ideas / (Schematic / circuit added 10/05) You can run initial high-level simulations of custom numerical algorithms, such as digital filters, using floating-point numbers in an environment such as C or Matlab. Unfortunately, you won't see include fixed-point effects, such as truncation due to limited precision and register overflow, until you use a Hardware Design Language (HDL), such as Verilog or VHDL. However, a technique that models these effects in C—the function "bit_limit" in Listing 1—provides faster execution and better portability than HDLs and allows early exploration of the trade-off between bus width and performance.
MW Active Antenna: This circuit is designed to amplify the input from a telescopic whip antenna. The preamplifier is designed to cover the medium waveband from about 550Khz to 1650Khz. The tuning voltage required is 1 to 12 volts and can be obtained from a 10k potentiometer connected to the 12 Volt power supply. RV1 is the gain control allowing weak signals to be amplified or strong signals to be attenuated. The control voltage is applied to gate 2 of TR1, a dual-gate MOSFET, the signal voltage applied via gate 1; the input signal being tuned via L1 and the two varicap diodes at the MOSFET's input and also by L2 and the varicaps at the MOSFET's drain terminal. Both tuned circuits provide high selectivity across the entire tuning range. To aid stability the MOSFET.... (added 10/05)
RISC µP Implements Fast FIR Filter: 01/21/99 EDN-Design Ideas / (Schematic / circuit added 10/05) When it comes to implementing a fast FIR filter, current RISC µPs can compete with DSP µPs. The FIR algorithm continuously implements the following equation: N=n–1 Out=Sum[in(t[-]n)coeff(n)] N=0,....
Subwoofer Equalizer: The Linkwitz transform circuit is a hugely flexible way to equalize the bottom end of a sealed loudspeaker enclosure. A speaker that is corrected using this method is flat from below resonance to the upper limit of the selected driver. The low frequency roll off point is determined by the parameters of the transform circuit. Should the enclosure size be too small and cause a lump in the response before roll off, this is also corrected. A conventional active crossover network is then used to divide the subwoofer signal from the main channel signals. Note that there is also a separate spreadsheet calculator available for calculating component values for different situations not handled by the original circuit. (Electronic Circuit added 03/06)
Micro Power AM Broadcast Transmitters: In this circuit, a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a Class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable VFO with a capacitor/resistor combination. (added 4/02)
Pi Filter has Sharp Notch: Electronic Design 10/1/97 Simple filter network makes a great low-pass filter having a sharp notch just outside passband. Can be implemented as active filter using GIC circuit. Voted best of issue! (added 9/04)
One-transistor Regenerative AM Receiver: A classic design revamped slightly. Features a single-transistor regen stage, and a range of 1000 miles with a 4-foot antenna. Perhaps the best "survival radio", yet. Now updated with speaker amplifier. (circuit design added 7/06)
Battery Low Voltage Beeper: This circuit provides an audible and visual low voltage warning for 12V battery powered devices. Idle current: 6ma Low Voltage Warning current: 15ma…. (schematic added 9/02)
Beeper: This circuit produces sound of a beeper like one in pagers which produces a "beep-beep" sound. Basically circuit consists of a 555 timer oscillator which is turned ON and OFF periodically. The first C (left) oscillates at about 1Hz. The second IC is turned ON and OFF by first IC. The first IC determines how fast second IC.... (added 10/05)
Big Ben Sound: This circuit produces famous Big Ben sound. It produces "ding dong" sound when switched ON. Basically circuit alternates between two frequencies which are adjustable. This produces "ding-dong" sound. The first C (left) oscillates at about 1Hz. The second IC's tone is modulated by changing voltage at output of first IC..... (added 10/05)
ZN414 Portable AM Receiver: An AM portable radio receiver made from the ZN414 IC. The ZN414 IC has now been replaced by the MK484 which is identical in performance and pinout. (added 10/05)
AM DSB Transmitter for Hams: circuit diagram of simple double side band suppressed carrier (DSBSC) transmitter for hams. Circuit uses crystal oscillator, crystal can be switched for multi band operation. . (added 9/04)
AM Transmitter (circuitdb): circuit is deliberately limited in power output but will provide amplitude modulation (AM) of voice over the medium wave band. The circuit is in two halfs, an audio amplifier and an RF oscillator. (added 2/07)
Micro Power AM Broadcast Transmitter: In this circuit, a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a Class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable (VFO) with a capacitor/resistor combination. (added 4/02)
A 4 to 20 mA loop needs no external power source: 09/13/01 EDN Design Ideas / (added 11/05) The simple circuit in Figure 1 uses a low-current-drain MAX4073H amplifier to sense the current flowing through a 4- to 20-mA loop. The circuit senses the current through a 1Ω resistor with a fixed gain of 100 and uses no battery or dc power supply. The low current drain of the amplifier (0.
Active Feedback IC Serves as Current Sensing Instrumentation Amplifier: 07/24/03 EDN Design Ideas / (Circuit / schematic design added 6/06) High-speed current sensing presents a designer with some significant challenges. Most techniques for sensing current involve measuring the differential voltage the current produces as it flows through a sense element, such as a resistor or a Hall-effect device. The differential voltage across the sense element is generally small and is often riding on a common-mode voltage that is considerably ......
Active feedback IC Serves as Current sensing instrumentation Amplifier: 07/24/03 EDN Design Ideas / (added 1/05) High-speed current sensing presents a designer with some significant challenges. Most techniques for sensing current involve measuring the differential voltage the current produces as it flows through a sense element, such as a resistor or a Hall-effect device. The differential voltage across the sense element is generally small and is often riding on a common-mode voltage that is considerably ......
AN-245: Instrumentation Amplifiers Solve Unusual Design Problems: AN-245 - Analog Devices Application Notes (added 2/06) Traditionally Considered Only for Transducer-Conditioning Applications, Instrumentation Amplifiers Bring Unique Performance Benefits to a Range of Other Applications as Well.
AN-345: Grounding for Low-and-High-Frequency Circuits: AN-345 - Analog Devices Application Notes (added 2/06) Know Your Ground and Signal Paths for Effective Designs. Current Flow Seeks Path of Least Impedance-Not Just Resistance....
AN35 High-Side Current Sensing: Considerations and Applications for High-Side Current Monitoring: Zetec Semiconductors - Applications Notes - A guide for using the ZXCT range of products. Contained within the note are application ideas for extended supply ranges, a circuit for bi-directional current sensing and an over-current/short circuit protection circuit. Now updated and contained within AN39 (added 2/06)
AN39 Current Measurement Applications Handbook: Zetec Semiconductors - Applications Notes - This applications handbook explores how the requirements affect the design for AC and DC current measurement and the implications on cost and performance for different approaches. (added 2/06)
AN-589: Ways to Optimize the Performance of a Difference Amplifier: AN-589 - Analog Devices Application Notes (added 2/06) This Application Note presents several ways to build and optimize the performance of a discrete difference amplifier. It also recommends amplifiers that will make the overall solution cost/performance competitive with monolithic instrument amplifiers.
Analog input circuit Serves any microController: 12/20/01 EDN - Design Ideas / (Electronic circuit added 10/03) The simple ADC in Figure 1 is perfect for getting analog signals into a purely digital microcontroller. Using just five surface-mount parts, you can assemble it for less than 50 cents (1000), which is approximately half the cost of a single-chip-ADC approach in the same volume. Moreover, this design takes only one pin from the microcontroller to operate. .
Bias Voltage and Current Sense Circuits for Avalanche Photodiodes: AN92 - Linear Technology - Avalanche photodiodes, used in laser based fiberoptic systems, require high voltage bias and accurate, wide range current monitoring. Bias voltage varies from 15V-90V and current ranges from 100nA to 1mA, a 10,000:1 dynamic range. This publication presents various 5 volt powered circuits which meet these requirements. Appended sections detail specific circuit techniques and cover measurement practice.
1.5 Volt Amplified Ear: Useful to listen in faint sounds1.5-Volt
Battery
operation, includes electret microphone preAmplifier which runs from1.5-Volt DC and can directly drive32 Ohms impedance mini-earphones (added 9/04)
100 Watt Guitar Amplifier: The original of the unit above. Retained for posterity, and has speaker box details (schematic added 6/07)
100 Watt RMS Amplifier: This is a100-Watt basic power amp that was designed to be (relatively) easy to build at a reasonable cost. It has better performance (read: musical quality) than standard STK module amps that are used in practically every mass market stereo receiver manufactured today. When I originally built this thing, it was because I needed a100 WPC amp and didn't want to spend any money. So I designed around parts I had in shop. (added 4/02)
101 Watt Guitar Amplifier: The original of the unit above. Retained for posterity, and has speaker box details (schematic added 6/07)]
2 Channel Power Amplifier: 2-Channel Power Amplifier based on NTE1606. circuit is powered by a12V,10-Amp power supply. power of output channels is4 W connected to 8-ohm loudspeakers (added 2/07)
AC Coupling Instrumentation Amplifier Improves Rejection Range Of Differential Dc Input Voltage: 09/30/04 EDN Design Ideas / (added 12/04) The need for conditioning low-level ac signals in the presence of both common-mode noise and differential dc voltage prevails in many applications. In such situations, ac-coupling to instrumentation and difference amplifiers is mandatory to extract the ac signal and reject common-mode noise and differential dc voltage....
Amplifier And Current Source Emulate Instrumentation Amplifier: 11/13/03 EDN Design Ideas / (added 12/04) The classic three- or two-op-amp instrumentation-amplifier circuits are standard ways to amplify a small-amplitude differential signal contaminated with high common-mode noise. In some applications, the signal source is floating with high-series-output impedance and thus requires an appropriate high-input-impedance amplifier....
Lowpass Filter uses Only Two Values: 07)/05/01 EDN Design Ideas / (added 12/04) In recent years, image-parameter design of LC filters has received new consideration (references 1 and 2). The composite lowpass filter uses interior constant-k full sections terminated by m-derived half-sections. For best passband response, you usually select m to equal 0.6. However, m=0.5 can still give useful filter performance while reducing the number of component values....
Build an Adjustable High Frequency Notch Filter: 02/06/03 EDN Design Ideas / (added 12/04) Although you can obtain universal, resistor-programmable switched-capacitor filters that are configurable as notch filters, most cannot operate at bandwidths higher than 100 kHz. Furr, typically 16to 20-pin packages do not include a continuous-time, antialiasing filter to prevent spurious signals from appearing at output....
Closing the Loop Deepens Notches: 05/07)/02 EDN Design Ideas / (added 12/04) Notch filters remove a single unwanted frequency from an input signal. They are also a vital component of pulse-shaping networks, such as time-averaging filters. You can tune a state-variable filter over a wide range by changing the time constants of its integrating amplifiers (references 1, 2, and 3). ...
High Q Notch Filter: National Semiconductor Application Notes first published28-Jun-1996 (app note added 4/02)
High-Q 60-Hertz Notch Filter: This high-Q notch filter is based on the "Twin-T" design. It produces a very deep notch in the response curve at about 59.7 Hz. This is useful to remove 60-Hz hum and noise from audio recordings or live performances. Response is down over -60db at the center point. The LM3900 Norton opamp was chosen since it doesn't require extra components for single-supply operation.... (circuit design added 7/06)
Notebook Power Supply has Two Outputs: 03/03/94 EDN-Design Ideas / (added 3/06) The notebook-computer supply in Fig 1 powers the 5V logic and derives an adjustable -24V supply for an LCD's backplane. The design uses only a high-efficiency buck regulator (Si9150) and an NMOS/PMOS, dual-power-FET chip set (Si9943), eliminating the extra parts required when you implement both supplies independently. Because of the low on-resistances of the dual FETs, this circuit can achieve better than 92% efficiency at 7.2V input and full-load output (7.6W)....
RC Notch Filter Twin T: The twin T notch filter can be used block an unwanted frequency or if placed around an op-amp as a bandpass filter. The notch frequency occurs where the capacitive reactance equals the resistance Xc=R and if the values are close, the attenuation can be very high and the notch frequency virtually eliminated. (added 4/02)
Reverse RIAA Equaliser: Test phono preamps for correct equalisation, or convert unused phono inputs. (circuit added 6/07)
1-Wire Barometer: circuit requires an additional power source or than that of 1-Wire network. MPX4115 requires about 7 ma of current. This is more than a 1-Wire network can provide without an elaborate circuit to store parasitic power from 1-Wire network for short burst of current for pressure measurements. Two voltage regulators are used to provide both 5.0 and 10.0 voltages from a source of DC power ranging from 12 to 24 volts. (added 2.07)
Method of Designing Multiple Order All Pole Bandpass Filters by Cascading 2nd Order Sections: AN27A Linear Technology Presents two methods of designing high quality switched capacitor bandpass filters. Both methods are intended to vastly simplify the mathematics involved in filter design by using tabular methods. The text assumed no filter design experience but allows high quality filters to be implemented by techniques not presented before in the literature. The designs are implemented by numerous examples using devices from LTC's SwitchedCapacitor filter family: LTC1060, LTC1061, and LTC1064. Butterworth and Chebyshev bandpass filters are discussed. (app note added 6/06)
Micro-power Band-pass Network: Circuit Ideas for Designers Application Notes Advanced Linear Devices, Inc. (app note added 6/06)
Simple Method of Designing Multiple Order All Pole Bandpass Filters by Cascading 2nd Order Sections: AN27A Linear Technology Presents two methods of designing high quality switched capacitor bandpass filters. Both methods are intended to vastly simplify the mathematics involved in filter design by using tabular methods. The text assumed no filter design experience but allows high quality filters to be implemented by techniques not presented before in the literature. The designs are implemented by numerous examples using devices from LTC's SwitchedCapacitor filter family: LTC1060, LTC1061, and LTC1064. Butterworth and Chebyshev bandpass filters are discussed. (app note added 6/06)
Single Op-Amp Bandpass Filter: A bandpass filter passes a range of frequencies while rejecting frequencies outside the upper and lower limits of the passband. The range of frequencies to be passed is called the passband and extends from a point below the center frequency to a point above the center frequency where the output voltage falls about 70%.... (added 2/07)
A Collection of Differential to Single-Ended Signal Conditioning Circuits for Use with the LTC2400 a 24-Bit No Latency Δσadc in an SO-8: AN78 Linear Technology This application note describes six low power differential-tosingleended signal conditioning circuits for LTC2400 No Latency ΔΣTM 24-bit ADC. These circuits offer customer a number of choices for conditioning differential input signals as low as 5mV to as high as ±2.5V, as well as operation on a single 5V or ±5V supplies. Each circuit description also covers circuit design and implementation techniques that can help preserve LTC2400's inherently high effective resolution. AN78 concludes with two circuits for digitizing temperature when using an RTD or Type S rmocouple.
Acquisition system is Programmable on the fly: 10/12/95 EDN-Design Ideas / (added 11/05) The programmable data-acquisition system in Fig 1 can take 333k samples/sec using a 3-µsec sampling ADC, IC3. Multiplexer IC1 and programmable gain amplifier (PGA) IC2 provide four truly differential channels and four decade gains of 1, 10, 100, and 1000. These features allow circuit to handle low-signal sensors without additional conditioning circuitry. The circuit does not require an S/H amplifier due to ADC's sampling structure. If you want to handle noisy and high-speed signals, you may need to add an antialiasing filter in front of ADC. The heart of system is a 4x4 register file, IC5, which essentially controls ....
ADC to PC interface Transfers data in nibbles : 12/09/99 EDN-Design Ideas / (added 6/06) -The circuit in Figure 1 uses a Centronics printer port to interface an eight-channel, 8-bit ADC to a PC. The circuit cuts cost of addressing and decoder circuitry and saves one expansion slot for interfacing. The design uses three of subport...
AN26(A-R) Interfacing the LTC1090/1/2: AN26 Linear Technology A collection of interface applications between various microprocessors/ controllers and LTC1090 family of data acquisition systems. The note is divided into sections specific to each interface. (app note added 2/06)
AN-347: Shielding and Guarding: AN-347 - Analog Devices Application Notes (added 2/06) How to Exclude Interference-Type Noise. What to do and Why to do it-A Rational Approach
AN-584: Using the AD813X Differential Amplifier: AN-584 - Analog Devices Application Notes (added 2/06) The AD813x differs from conventional op amps by the external presence of an additional input and output. The additional input, VOGM, controls the output common mode voltage.
AN-589: Ways to Optimize the Performance of a Difference Amplifier: AN-589 - Analog Devices Application Notes (added 2/06) This Application Note presents several ways to build and optimize the performance of a discrete difference amplifier. It also recommends amplifiers that will make the overall solution cost/performance competitive with monolithic instrument amplifiers.
Composite Amp Provides High Gain and Bandwidth: 04/28/94 EDN-Design Ideas / (Electronic Schematic / circuit added 04/02) The composite circuit in Fig 1 couples the output drive and slew rate of a current-feedback amplifier, IC2, with the low-noise and low-offset characteristics of a voltage-feedback operational amplifier, IC1. The circuit achieves gains as high as 1000, while showing little variation in frequency characteristics with gain. This circuit suits applications requiring high gain and wide dynamic range, such as ultrasound, radar, digital radio, and other high-noise applications....
Analog Input Circuit Serves Any Microcontroller: 12/20/01 EDN Design Ideas / (added 10/03) The simple ADC in Figure 1 is perfect for getting analog signals into a purely digital microcontroller. Using just five surface-mount parts, you can assemble it for less than 50 cents (1000), which is approximately half cost of a single-chip- ADC approach in same volume. Moreover, this design takes only one pin from microcontroller to operate. .
LED Driver Delivers Constant Luminosity: 06/12/03 EDN Design Ideas / (added 12/04) The circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1) but offers improved, more reproducible performance. The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to variations of transistor gain. Transistors Q1 and Q2 form an astable flip-flop....
Network Imitates Thermocouples: 11/08/01 EDN Design Ideas / (added 12/04) Thermocouples find widespread use for temperature measurement in systems. During system design or testing, you must observe the system's response at different temperatures. However, it's inconvenient to heat a thermocouple every time you need to check a system's performance. You can use the simple trick of touching the thermocouple with a hot soldering iron, but this method provides only ... ...
Positive Feedback Yields Fast Amplifier with Precision DC Offset: 04/01/04 EDN Design Ideas / (added 1/05) Some signal-processing applications require a high-speed, low-noise, dc-coupled amplifier that incorporates a precision dc-offset adjustment. Examples include oscilloscopes, in which the offset adjustment typically acts as a "position" control), ADC-input gain blocks, and scanning-ion-beam-microscopy deflection circuitry....
Video Emitter uses Battery Power: 08/30/01 EDN Design Ideas / (added 12/04) The block diagram in Figure 1 shows how to make a cable-free, direct-video system. The system allows users to walk from booth to booth at an exhibition to interview people and to display the interviews in real time on three screens at key locations. You can use the small and simple system each time you need to capture image and sound on the run. ...
Anticipating timer switches before you push the button: 04/03/03 EDN-Design Ideas / (Electronic circuit added 10/03) (Editor's note: This Twilight Zone-worthy circuit will be the subject of an upcoming network sitcom, My Big Fat Anticipating Timer.) It happens to almost everyone that an apparatus or system should have been turned off a moment ago. The device in question could be the car heater, the air conditioner, the lights
Air Flow Detector #1: This simple circuit uses an incandescent lamp to detect airflow. With the filament exposed to air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As air flows over the filament it cools down, thus lowering its resistance. A comparator is used to detect this difference and light an LED. With a few changes, the circuit can be connected to a meter or ADC to provide an estimation on the amount of airflow. (Electronic Schematic / circuit added 4/02)
Voltage to Current Converter Drives White LEDs: 06/27/02 EDN Design Ideas / (added 12/04) You sometimes need to drive a white LED from one 1.5V battery. Unfortunately, the forward voltage of a white LED is 3 to 4V. So, you would need a dc/dc converter to drive the LED from one battery. Using the simple circuit in Figure 1, you can drive one white LED or two series-connected green LEDs, using only a few components....
Ways to Optimize the Performance of a Difference Amplifier: AN-589 Analog Devices Application Notes (app note added 6/06) This Application Note presents several ways to build and optimize the performance of a discrete difference amplifier. It also recommends amplifiers that will make the overall solution cost/performance competitive with monolithic instrument amplifiers.
Audio-test accessory isolates and matches loads: 3/16/06 EDN Design Ideas / (added 10/06) This low-cost, switchable, dual-impedance transformation circuit comprises a single conventional transformer and two minimum-loss pads.
High-impedance voltmeter: An ideal voltmeter has infinite input impedance, meaning that it draws zero current from the circuit under test. This way, there will be no "impact" on the circuit as the voltage is being measured. The more current a voltmeter draws from the circuit under test, the more the measured voltage will "sag" under the loading effect of the meter, like a tire-pressure gauge releasing air out of the tire being measured...(schematic added 6/07)
40 Meter Popcorn Superhet Receiver: This schematic is a relatively low-cost CW superhet receiver with a 4.00 MHz Intermediate frequency. re is no AGC or RF gain control, however this receiver has good large signal handling capability. This receiver uses just 6 bipolar transistors and an op amp for reasonable volume into headphones. Much of ideas/design of various stages must ... (added 02/05)
I.F. Amplifier: The I.F. transformer primary has 18 turns, the secondary winding has 4 turns. The capacitors across the IFT primaries are 82pF. The input/output transformer has 12 turns, tapped at 3 turns from ground. This transformer is wound on a ferrite core. The mosfets are 3SK45's. The diodes in the product detector are 1N34's. I use a six pole SSB filter from a scrap CB. The centre frequency is 7.8MHz. The -6db bandwidth is about 2.5KHz. (added 02/05)
Tunable IF with TDA7000: The main motive of the mods was not that the circuit didn't work right, but were several tries to add some kind of frequency indicator to the receiver. The left RCA plug and associated components are witnesses to the last version, adding a FET buffer amplifier and taking signal from the oscillator coil. (added 02/05)
4 MHz Amplitude Modulated RF Source : A while back I needed an amplitude modulated signal source at 4 MHz. This circuit was literally thrown together with parts laying on the bench. I built it dead bug style on a piece of copper clad board. It should work with little or no modification, other than the selection of the crystal, at other frequencies. At lower frequencies you might have to increase the capacitor values to get it to oscillate, and at higher frequencies, you might have to reduce the capacitor values a little...(circuit added 6/07)
AM/FM/SW Active Antenna: This circuit shows an active antenna that can be used for AM, FM, and shortwave SW. On the shortwave band this active antenna is comparable to a20 to30 foot wire antenna. This circuit uses receivers that use untuned wire antennas, such as inexpensive units and car radios. L1 can be selected for the application (added 4/02)
Algorithm Extracts Roots of Decimal Numbers: 04/29/99 EDN-Design Ideas / (Schematic / circuit added 10/05) "Algorithm extracts cube root" (EDN, Jan 15, 1998, pg 100) covers only the one-third power (cube root). In contrast, the C routine in Listing 1 calculates the Kth root (X1/K) of positive decimal numbers X. Both K and X can vary widely. You type in X, K, and an estimate of the root; the routine then calls the calcRoot function in the software program. Upon calculating the root, the routine prints on screen the number of iterations performed and the root result X1/K. The routine raises this result to the Kth power and displays the result so you can make a comparison with the original X. The algorithm applies a Newton-Raphson approach to the equation Y=X1/K. If you differentiate the equation and express it in recursive form, you obtain....
White LED Driver provides 64 step logarithmic dimming: 06/10/04 EDN Design Ideas / (added 1/05) The circuit in this Design Idea is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels. The circuit drives as many as four white LEDs from a 3.3V source.
Composite Amplifier Improves Noise : 08/04/94 EDN-Design Ideas / (Electronic Schematic / circuit added 4/02) Amplifying low-signal levels for signal processing often stretches a single op amp's abilities. A composite design can improve the input noise for detecting extremely small signals and can enhance output-drive ability. Both the op amp's noise terms and the thermal noise of the components limit the minimum noise in an op-amp-based design. Furthermore, amplifier noise figures are not at their minimum for low-impedance sources such as 50 Ohm. Using a transformer is a common technique to achieve matched input impedance for maximum power transfer. Fig 1 shows one example, which follows the transformer with a composite amplifier to achieve a lower input noise figure...
A Versatile Hybrid Synthesizer for UHF and Microwave Projects: Controlled by PC parallel port, this hybrid DDS/PLL synsizer delivers full-octave coverage between 1000 and 2000 MHz with sub-1 Hz resolution and commercial-quality phase-noise performance. (added 6/06)
Ultrasonic radar: This is a very interesting project with many practical applications in security and alarm systems for homes, shops and cars. It consists of a set of ultrasonic receiver and transmitter which operate at the same frequency. When something moves in the area covered by the circuit the circuit’s... (electronic design added 6/07)
Amplifier Requires No DC Bias: 03/16/00 EDN-Design Ideas / (added 11/05) Intrinsically capacitive transducers and or high-impedance signal sources usually require ac coupling and a buffer amplifier to condition signal for furr processing. Buffers take many forms, but most of m compromise signal quality through use of external resistors that provide a dc path for input bias current. Recent improvements in op-amp technology allow ac-coupled inputs without need for bias resistors. The new op amps have inputs that operate within supply-voltage span. Some are CMOS, but many use complementary bipolar transistors. For latter, each input connects....
Behind the Switch Symbol: AN-355 - Analog Devices Application Notes (app note added 2/06) Use CMOS Analog Switches More Effectively When You Consider Them as Circuits
Long Loopstick AM Radio Antenna: Wound on a3-foot length of PVC pipe, the long Loopstick antenna was an experiment to try to improve AM radio reception without using a long wire or ground. It works fairly well and greatly improved reception of a weak station130 miles away. A longer rod antenna will probably work better if space allows. The number of turns of wire needed for the Loopstick can be worked out from the single layer, air core inductance formula: (Electronic Schematic / circuit added 4/02)
Add Programmable Gain, Attenuation: AN-254 Analog Devices Application Notes (app note added 6/06) Simple CMOS Multiplying DAC Circuit Provides Digital Control of Gain and Attenuation of Analog Signal
Precision Divide by Two Analog Attenuator Needs No External Components: 03/17/05 EDN Design Ideas / (added 11/05) Many modern A/D converters offer only a 5V input range, and using these converters with a 65V or larger input signal gives the designer a problem: how to discard half of a good analog signal without introducing errors and distortion. To solve the problem, you can use an attenuator comprising two operational amplifiers and two resistors (Figure 1).
30 Ddm to +30 Ddm Audio Level Meter: circuit with balanced input and adjustable gain to drive needle type VU meter, uses special amplifier module from Op-Amp Labs (added 4/02)
Audio Transformer #2: notes on using audio transformers for balanced signal interfacing (added 4/02)
Bluetooth Headset: Intersil Application Block Diagram (app note added 6/06)
AN-348: Avoiding Passive-Component Pitfalls: AN-348 Analog Devices Application Notes (app note added 2/06) The Wrong Passive Component Can Derail Even Best Op Amp or Data Converter. Here Are Some Basic Traps to Watch For.
Applications for a Switched-Capacitor Instrumentation Building Block: AN3 Linear Technology This application note describes a wide range of useful applications for LTC1043 dual precision instrumentation switched capacitor building block. Some of applications described are ultra high performance instrumentation amplifier, lock-in amplifier, wide range digitally controlled variable gain amplifier, relative humidity sensor signal conditioner, LVDT signal conditioner, charge pump F/V and V/F converters, 12-bit A/D converter and more. (app note added 6/06)
ADN2891 Evaluation Board: AN-762 Analog Devices Application Notes (app note added 2/06) This application note describes ADN2891 evaluation board.
AN-762: ADN2891 Evaluation Board: AN-762 Analog Devices Application Notes (app note added 2/06) This application note describes ADN2891 evaluation board.
Limiting Amplifier is Digitally Programmable: 06/04/98 EDN-Design Ideas / (added 11/05) Amplitude limiters are necessary in many systems, such as radar and FM receivers, for which the system cannot allow the amplitude of the signal to exceed the given positive, negative, or both limits. In the circuit in Figure 1, amplifier IC4B's maximum output is digitally programmable over ±2 to ±10V in 2n steps, where n is the number of bits of the DAC. IC1, a precision 10V reference, provides a full-scale reference current, IREF=VREF/R1=2 mA, to IC2, a multiplying DAC. IC3's output voltage, VL, is the sum of the product of the digital word and unipolar...
5 Zone Alarm: Each zone uses a normally closed contact. se can be micro switches or standard alarm contacts (usually reed switches). Zone 1 is a timed zone which must be used as entry and exit point of building. Zones 2 5 are immediate zones, which will trigger alarm with no delay. Some RF immunity is provided for long wiring runs by input capacitors, C1-C5. C7 and R14 also form a transient suppresser. key switch acts as Set/Unset and Reset switch. For good security this should be .... (added 09/05)
A CMOS Single Zone Intruder Alarm: This circuit features automatic Exit and Entry delays - timed bell cut-off - and system reset. It has provision for normally-open and normally-closed switches - and will suit all of the usual input…(added 05/07)
A Simple Electronic Buzzer: This very simple circuit just uses a couple of resistors, a capacitor and easily available 555 timer IC. The 555 is setup as an astable multivibrator operating at a frequency of about 1kHz that produces a shrill noise when switched on. The frequency can be changed by varying 10K resistor. (added 10/06)
A Transistor Based - Single Zone Alarm: This circuit features automatic Exit and Entry delays - timed bell cut-off - and system reset. It has provision for normally-open and normally-closed switches - and will suit all of the usual input...(added 05/07)
Automatic Intruder Alarm: This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It's designed to be used with the usual types of...(added 05/07)
105 W 6 Channel Surround Sound: This reference design allows customers with limited knowledge of digital audio amplifiers to quickly build solutions, which meet Dolby, EMI and FTC standards, reducing the time-to-market for new consumer audio products. This 6 channel reference design, based on the TDA8925ST and TDA8926J power stages, is available with an output power of 5x15 W + 1x30 W. (circuit design added 3/05)
Surround Processor: Simple Surround Processor. This is built with only conventional parts, and digital delay block, too. So it is very easy to build. (Circuit / schematic design added 6/06)
30 Ddm to +30 Ddm Audio Level Meter: circuit with balanced input and adjustable gain to drive needle type VU meter, uses special amplifier module from Op-Amp Labs (Circuit / schematic design added 6/06)
Guitar Control: CaStand-alone, 9V battery powered unit . Three-level input selector, three-band tone control (circuit design added 3/05)
160 Baud ALDL Hardware Interface: This interface allows the vehicle's ALDL data stream to be displayed in real time on a PC using simple software. The hardware is designed to be able to be constructed by the average hobbyist who has a temperature controlled soldering iron and basic skills in constructing simple electronics. It uses a minimum of (readily available) components consistent with good electronics design. (Electronic circuit added 4/05)
6A door lock motor driver for automotive: AN456, put at low level the enable of the L9937, confirming the hardware switch-off of the motor ; in this condition an output of the half bridge is in... (app note added 6/06)
AN10 Automotive Relay Drivers using the ZVN4206AV: Protection Free Interfacing with Avalanche Rated MOSFETs: Zetec Semiconductors - Applications Notes - An alternative solution is provided to the usual large package
Darlington
effected relay driver. The ZVN4206AV has been designed, processed and rated to withstand significant energy within the breakdown region. This allows the part to absorb back-emf and transient energy, thereby allowing lower component count circuits. (added 2/06)
3 Level Audio Power Indicator: Battery-operated Three LED display that connect it to loudspeaker output (added 6/06)
3 Tone Gong: Suitable for use as a door bell (added 6/06)
30 Ddm to +30 Ddm Audio Level Meter: circuit with balanced input and adjustable gain to drive needle type VU meter, uses special amplifier module from Op-Amp Labs (added 6/06)
Audio level meter (VU Meter): This circuit uses just one IC and a very few number of external components. It displays audio level in terms of 10 LEDs. The input voltage can vary from 12V to 20V, but suggested voltage is 12V. The LM3915 is a monolithic integrated circuit that senses analog voltage levels and drives ten LEDs providing a logarithmic 3 dB/step analog display. LED current drive is regulated and programmable, eliminating need for current limiting resistors. The IC contains an adjustable voltage reference and an accurate ten-step voltage divider. The high-impedance input buffer accepts signals down to ground and up to within 1.5V of positive supply. Furr, it needs no protection against inputs of ±35V. The input buffer drives 10 individual comparators referenced to precision divider. Accuracy is typically better than 1 dB. (added 9/06)
Old phones as an intercom (circuitsdb): From: mwandel@bnr.ca (Markus Wandel) I have recently thought about this and come up with a kludgy but workable scheme. Talking over the phones is easy. You put DC current through the phone and.... (added 2/07)
2 Line Output Combiner: Convert consumer equipment stereo signal to mono or combine audio signal from two different equipments to1-input (added 4/02)
Line Mixer #2: mix two line level sources to one-signal, includes separate volume controls for both signals, passive circuit (added 4/02)
Portable Mixer: High-quality modular design 9V
Battery
powered Very Low current drawing (added 9/04)
Stereo Mixer : Can mix four separate audio inputs to mono or stereo output signal (added 4/02)
Two Line Output Combiner: Convert consumer equipment stereo signal to mono or combine audio signal from two different equipments to1-input (added 4/02)
2W Amplifier: Amplifier operates in
ClassAB
mode; single 470R preset resistor controls quiescent current flowing through BD139/140 complimentary output transistors. Adjustment here, is a trade-off between low distortion and low quiescent current. Typically, under quiescent conditions, standby current may be 15 mA rising to 150 mA with a 50 mV input signal. A simulated frequency response is ... (added 2/07)
Dynamic Microphone Preamp : Notice how the transistor bias current flows through the microphone. A similar circuit can be used with an 8 ohm speaker but in that case you would put it in place of the emitter resistor. (added 2/05)
AB-111: Single-Supply Wien Bridge Oscillator: AB-111 Analog Devices Application Notes (app note added 2/06) Wien Bridge Oscillators require only one op amp, important in battery-operation. This circuit operates from a single 9V battery.
AN-106: A Collection of Amp Applications: AN-106 Analog Devices App Notes (app note added 2/06) Examines Some of Numerous and Widely Used Applications of Operational Amplifier
48 Input×16 Output Crosspoint IC Eliminates the Need for Multiplexer Amps: 02/20/03 EDN-Design Ideas / (Electronic circuit design added 02/05) Crosspoint switches are ideal for use in video-security systems, which accept multiple camera inputs while providing playback and multiple loop-through to multiple monitors. To provide video loop-through or monitor outputs, these systems often require additional multiplexer amplifiers that can drive standard video loads...
NTSC-to-VGA Scan Converter: This is a scan converter for NTSC signal from TV, VCR, LD or DVD to VGA conversion. Your VGA monitor will able to be used for video monitor. (Schematic / circuit added 10/05)
Video Amplifier: This is a Video amplifier that has been constructed by a single special IC LH0024. (Electronic Circuit diagram added 03/03)
Video Inverter: This is a simple one-transistor circuit to invert the whole video signal, including sync pulses. (Electronic Schematic / circuit added 4/02)
A Geophone/Hydrophone Acquisition Reference Design: AN-566 Analog Devices Application Notes (app note added 2/06) The AD1555/AD1556 24-Bit Sigma-Delta ADC Chipset Provides for Direct Acquisition of High Dynamic Range Sensors.
Analog Switch Expands I 2 C Interface: 11/22/01 EDN Design Ideas / (added 12/04) Perhaps the most effective way to gain board space and increase component density is to minimize wiring on the board. A widely used architecture that allows such miniaturization is the I2C bus. Comprising only a bidirectional data line, SDA, and a clock line, SCL, this bus requires no chip selects or other additional connections. ...
2 Wire Lamp Flasher: Ideal to operate3 to24
VoltDC
existing on-Circuit lamps LED operation is also possible (added 9/04)
220 Volts Flashing Lamps: Especially designed for Christmas tree lamps to replace old rmally-activated switches (added 9/04))
2-wire Lamp Flasher: This circuit has been designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert circuit between existing lamp and negative supply. Especially suited for car or panel pilot lights, this device can drive lamps up to 10W.... (design added 11/06)
Bandpass Filter: This circuit is taken from the Progressive Communications Receiver in most of the recent ARRL Handbooks. Values for the 40 meter band are shown. (Electronic circuit design added 02/05)
Notch Filter Is DC Accurate: 03/02/95 EDN Design Ideas / (circuit added 7/02) Most active filters exhibit noise, distortion, gain error, and dc offset. However, a filter topology that separates the dc and ac paths can eliminate the last two of these unwanted behaviors (Fig 1a). The dc path in this circuit has no op amps and, therefore, no dc offset. The dc path does not have a dc gain error other than -6 dB of attenuation that the R1/R2 divider causes. (This attenuation is absent if you omit the R2 termination.) The ac path consists of C1 and a synthetic inductor comprising two wideband transconductance amplifiers and associated components. The result is an active circuit that emulates the passive filter of Fig 1b...
Battery Backup Converter uses One NiCd Cell: 02/03/97 EDN Design Ideas / (Circuit / schematic design added 6/06) Notebook computers and other portable equipment often use a backup battery to retain memory contents during replacement of the main battery. Such "bridge batteries" usually consist of five or six series-connected NiCd coin cells. They're expected to keep the system alive for approximately 5 minutes—plenty of time to swap batteries. The circuit in Figure 1 reduces size, weight, and cost by using one NiCd cell instead of five or six. A Saft VB4E 40-mAhr NiCd coin cell has enough capacity to keep a typical notebook computer in suspend mode for approximately 10 minutes. All components (excluding the coin cell) consume less than 1/2 in.2 of pc-board area, and the cost savings from fewer cells help pay for the added circuitry.....
Buck Converter Handles Battery Backup System: 04/24/03 EDN Design Ideas / (added 12/04) A synchronous buck converter is inherently bidirectional. That is, it transfers energy from input to output as a buck regulator when the output voltage is low, but, when the output voltage is high, the converter acts as a boost regulator, transferring power from output to input. This Design Idea shows how to use this bidirectional energy transfer to automatically recharge a battery when the mai......
Microcontroller Provides SrAM Battery Backup: 06/26/03 EDN Design Ideas / (added 12/04) To maintain content in the event of power loss, many designs that include SRAM require a dedicated device that can automatically switch from a standard power supply to battery operation. Microcontrollers seldom find use in power-switching applications. Because microcontrollers typically operate from the primary power supply, they stop execution if that supply drops, thereby making it impossible......
Amplified Zener: A 13 volt Zener diode will work well for charging a 12 volt battery on Standby use. Or use a 14 volt zener a diode for a Standard 14.6 volt charge…. (circuit / schematic design added 10/06)
Battery Charger: Current and Voltage Regulated for Sealed Lead Acid types (electronic circuit added 10/06
Broken Charger-Connection Alert: Detects if a device is not properly connected to its supply. Suitable for battery chargers, portable appliance supplies etc. (added 3/050
Step Up supply charges battery while serving load : The circuit in Fig 1 supports portable applications in which a microprocessor controls battery charging. Step-up switching regulator IC1 boosts VIN (5V) to supply a combination of charging and load current. (Note that the 5V source must have short-circuit protection.) IC2 is a high-side current-sense amplifier that monitors charging current. Commands from the processor are CHARGE ON /OFF and FAST/TRICKLE CHARGE 06/08/95 EDN-Design Ideas / (added 11/05)
The Amplified Zener: A 13 volt Zener diode will work well for charging a 12 volt battery on Standby use. Or use a 14 volt zener a diode for a Standard 14.6 volt charge…. (circuit / schematic design added 10/06)
Zap Adapter: "Don't throw away those seemingly un-chargeable, rechargeable batteries; they could very well be brought back to life with the aid of this simple circuit." (circuit added 9/04)
Analog Circuit is Accurate Battery Fuel Gauge: Unpublished 10/98 Circuit acts as a fuel monitor for a rechargable battery, typically NiCd or NiMH chemistries. Analog type needle output meter appears like an automobile gas gauge. (added 9/04)
Battery Simulator Provides Current Limiting : 08/01/97 EDN Design Ideas / (added 5/03) A constant-voltage active load can perform as a battery during the charge cycle. You can set the load voltage from 5 to 35V by using potentiometer PV and thus can simulate batteries ranging from 6 to 32V.
Simple car battery tester: This circuit uses the popular and easy to find LM3914 IC. This IC is very simple to drive, needs no voltage regulators (it has a built in voltage regulator) and can be powered from almost every.... (added 2/07)
8 Random Flashing LEDs: This project flashes eight LEDs in an apparently random manner. It uses a 4060 combined counter and display driver IC which is designed for driving 7-segment LED displays. The sequence is not really random because seven of LEDs would normally be display segments, eighth LED is driven by an output that is normally used for driving furr counters. The table below shows sequence for LEDs. You can use less than eight LEDs if you wish and table may help you decide which ones to use for your purpose. (added 09/05)
Cranial Electrotherapy Stimulator: Current generated flows through clips placed on the earlobes Output current adjustable from 80 to 600 MicroAmperes (added 9/04)
Digital Step Km Counter Max.: Pedometer has a range of 9.950 meters with2-digits. Slip it in pants pocket for walking and jogging (added 02/05)
Soft on/Off Switch: Modern electronic equipment incorporate "push-to-on-push-to-off" switches that do not make noise as with old equipment. An example of this is the power button on a ATX computer cabinet. Here is a circuit that does the same. It can be used to turn on/off any electronic/electrical equipment that operates on any range of voltages. When the "ON/OFF" button is.... (added 10/05)
Active Feedback IC Serves as Current Sensing Instrumentation Amplifier: 07)/24/03 EDN Design Ideas / (added 12/04) High-speed current sensing presents a designer with some significant challenges. Most techniques for sensing current involve measuring differential voltage current produces as it flows through a sense element, such as a resistor or a Hall-effect device. The differential voltage across sense element is generally small and is often riding on a common-mode voltage that is considerably ......
AN-245: Instrumentation Amplifiers Solve Unusual Design Problems: AN-245 Analog Devices Application Notes (app note added 2/06) Traditionally Considered Only for Transducer-Conditioning Applications, Instrumentation Amplifiers Bring Unique Performance Benefits to a Range of Or Applications as Well.
AN-306: Synchronous System Measures µΩs: AN-306 Analog Devices Application Notes (app note added 2/06) Synchronous Detection Scheme Measures Low Resistances
Bass-Treble Tone Control Circuit: The LM1036 is a DC controlled tone (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems. An additional control input allows loudness compensation to be simply effected. Four control inputs provide control of bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a Zener regulated supply provided on circuit. Each tone response is defined by a single capacitor chosen to give desired characteristic.….. (added 6/06)
Better Volume Control: how to create a log pot that is better than "real" thing (added 4/02)
Build a Simple Soft Action Muting Switch: 10/14/04 EDN-Design Ideas / (added 10/05) The circuit in Figure 1 adds a soft muting switch with power-up/power-down muting to a line-level audio circuit. R4, C1, and JFET Q1 quietly ground a signal in 100 to 200 msec when you close S1 or release it when you open S1. Potentiometer R2, set to twice Q1's cutoff voltage, makes on/off transition....
Digital Volume Control has Log Taper: 04/11/02 EDN Design Ideas / (added 12/04) Digital potentiometers provide a compact and convenient way to attenuate audio-amplifier signals. However, most such potentiometers suffer from at least one flaw: a nonlogarithmic step increment. To avoid this problem, a user must usually step the potentiometer in a nonlinear sequence to simulate a logarithmic taper. ...
Guitar Control: CaStand-alone, 9V battery powered unit . Three-level input selector, three-band tone control (added 3/05)
Test Batteries Without a Voltmeter: 11/09/00 EDN-Design Ideas / (added 5/02) / PDF contains multiple circuits - scroll to find the one of interest / This circuit an easy approach to testing batteries without exiting the voltmeter. The battery holders in sizes AAA, AA, C, and D make this tester so much faster than a voltmeter.
1-Wire Barometer: The circuit requires an additional power source other than that of the 1-Wire network. The MPX4115 requires about 7 ma of current. This is more than a 1-Wire network can provide without an elaborate circuit to store parasitic power from the 1-Wire network for short burst of current for pressure measurements. Two voltage regulators are used to provide both 5.0 and 10.0 voltages from a source of DC power ranging from 12 to 24 volts. (Circuit / schematic design added 6/06)
Basic Stamp Based Altimeter: A method of determining altitude is by the use of barometric pressure; however, it is not done without difficulty. The relationship of pressure vs. altitude is not a linear one, it is actually a fairly complex one, which the army came up with in the 1930's. This is the equation for calculating .... (Circuit / schematic design added 6/06)
Portable Altimeter : Todd's Fascination with Flight. Read how Todd designed a portable altimeter using a micro-machined pressure transducer….. Gadget Freak / Design News (Schematic / circuit added 10/05)
A Simple Electronic Buzzer: This very simple circuit just uses a couple of resistors, a capacitor and easily available 555 timer IC. The 555 is setup as an astable multivibrator operating at a frequency of about 1kHz that produces a shrill noise when switched on. The frequency can be changed by varying 10K resistor. (added 6/06)
Battery Low Voltage Beeper: This circuit provides an audible and visual low voltage warning for 12V battery powered devices. Idle current: 6ma Low Voltage Warning current: 15ma…. (schematic / circuit design added 9/02)
Beeper: This circuit produces sound of a beeper like one in pagers which produces a "beep-beep" sound. Basically circuit consists of a 555 timer oscillator which is turned ON and OFF periodically. The first C (left) oscillates at about 1Hz. The second IC is turned ON and OFF by first IC. The first IC determines how fast second IC is turned ON/OFF and second IC determines tone of final output. By varying VR1, changeover rate can be adjusted. By varying VR2 tone can be adjusted. If you know something about electronics, you can try replacing 2nd 555 IC circuit with a piezoelectric buzzer. This saves one IC and associated components but buzzer cannot give a loud sound as speaker and also its tone cannot be varied. (added 6/06)
Bells Ring Generator: 3-Circuit options Can be synchronized to Christmas tree flashing lights (added 9/04)
Continuity Buzzer is Frugal with Power: 04/15/99 EDN-Design Ideas / (added 11/05) [Note: File contains multiple circuits. Scroll to find this one] The continuity detector in Figure 1 is based on
W Dijkstra
's "Fleapower circuit detects short circuits" (EDN, July 2, 1998, pg 122). The buzzer indicator allows you to devote full attention to making the connection without having to observe an LED. The circuit also consumes less power than Dijkstra's circuit. Power comes from two AA or AAA cells, which last for a period equal to their shelf life. Current consumption is less than 2.5 mA when the circuit detects continuity and less than 1.7 mA for an open circuit. Open-circuit voltage is less than 100 mV, and short-circuit current is less than 1 mA. You can use a number of op amps for IC1, provided that the specs indicate rail-to-rail operation with a low-voltage single supply....
Controller Provides Multiple Alarm Driver Formats: 01/15/98 EDN-Design Ideas / (added 08/05) DC/DC converters for use inside the telephone handset require operation from the high-source-impedance phone line. Additionally, the CCITT specifications call for maximum on-hook power consumption of 25 mA. The dc/dc converter in Figure 1 is 70%-efficient at an input power of 25 mA, providing 5V at 3.4 mA. Controlled, low-peak switch current ensures that the 48V input line experiences no excessive voltage drops during switching.
Cuckoo sound Generator: Agreeable, very close sound imitation Suitable for sound effects, door-bells etc. (added 9/04)
12 Volt Strobe Circuit: this circuit uses12V DC instead od mains AC. This is very good idea if you don't want to mess with direct mains voltage connected circuit or you want to run Strobe from batteries. (added 4/02)
120 VAC Lamp Chaser using Solid State Relays: (circuit / schematic design added 6/06)
120 Volt AC Lamp Chaser using Solid State Relays: This circuit is similar to LED clock using12 neon indicator lamps instead of LEDs. It operates from2 high capacity ni-cad cells (2.5 volts) which keep it going for a couple weeks. High voltage (70 volts) for neon lamps is obtained from a small switching power supply using a 74HC14 Schmitt trigger Squarewave oscillator, high voltage switching transistor, and10 mH high Q inductor. Most any small PNP transistors can be used that have a C/E voltage rating of 80 or more. (added 4/02)
Sound Controlled Flip Flop: Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder, burglar alarms, toys, etc. The circuit given here employs a condenser microphone as the pick-up. A two-stage amplifier built around a quad op-amp IC LM324 offers a good gain to enable sound pick-up upto four metres. …. (added 10/05)
2-Transistor Amplifier: A simple two-stage Amplifier. Use any general-purpose NPN with high gain. It will drive low impedance headphones directly. A speaker will probably require further boost. (added 10/05)
3.3V converter delivers 3W from Li-ION battery : 11/05/98 EDN-Design Ideas / (added 11/05) Lithium-ion batteries are rapidly gaining popularity in portable applications because of their superior energy density, low self-discharge rate, and high cell voltage. When you use one Li-ion battery to power a 3.3V dc/dc converter; however, you encounter a problem, because the battery voltage can be higher or lower than 3.3V. When fully charged, a Li-ion cell has approximately 4.2V output; when fully discharged, the voltage is approximately 2.5V. Therefore, you cannot use a simple buck or boost topology with a single inductor to generate a regulated 3.3V output. Some designs boost the voltage to approximately 4.3V and then use a low-dropout regulator to produce the 3.3V. This approach is inefficient, and efficiency is a crucial consideration in battery-powered applications. The circuit in Figure 1 offers a solution to the problem....
3-Band Equalizer: Using a single op-amp this easy to make equalizer offers three ranges, low frequency, mid frequency, and high. With component values shown there is approximately +/-20dB of boost or cut at frequencies of 50Hz, 1kHz and 10kHz. Supply voltage may be anything from 6 to 30 Volts. Maximum boost 20dB is only realized with maximum supply voltage. (added 4/05)
Add Current Boost to a USB Charger: 09/19/02 EDN Design Ideas / (added 1/05) The popular USB interface can charge a portable device while transferring data. But for high-capacity batteries, the 500-mA output current of USB hosts and powered hubs greatly extends the charging time. (Unpowered USB hubs supply no more than 100 mA.) Thus, a system that accepts charging power from an ac adapter as well as the USB port is more convenient....
AN34 ZXSC100 Power Supply for Digital Still Camera: Zetec Semiconductors - Applications Notes - A basic guide to the DC-DC Converter requirement and concept, including an introduction to the Zetex enhanced TO92 - the E-Line package, and some suggested applications where these components offer advantages. (app note added 7/06)
Application for a New Power Buffer: AN4 - Linear Technology - The LT1010 150mA power buffer is described in a number of useful applications such as boosted op amp, a feed-forward, wideband DC stabilized buffer, a video line driver amplifier, a fast sample-hold with hold step compensation, an overload protected motor speed controller, and a piezoelectric fan servo. (app note added 7/06)
Battery Booster Delivers 75W: 07/16/98 EDN Design Ideas / (added 07/02) The circuit in Figure 1 defies no laws of physics; it just makes creative use of an isolated dc/dc converter. The application uses the isolated converter in a nonisolated configuration to boost a 48V battery voltage to 60V. The PT3102 is a 15W isolated dc/dc converter that normally uses a 36 to 75V (48V-nominal) input voltage to provide a floating, or isolated, 12V output capable of 1.25A. The trick is to connect the negative-output lead and positive-input lead of the converter, thereby effectively stacking the 12V output on top of the 48V input. (Be aware that the original isolation and safety properties of the converter no longer exist in this configuration.)....
Boost 33V to 5V with Tiny Audio Amplifier: 09/05/02 EDN Design Ideas / (added 12/04) This charge-pump circuit quietly converts a 3.3V source to 5V at 500 mA (figures 1 and 2). National's (www.national.com) LM4871LD power amplifier makes this design idea both possible and practical, thanks to its low output resistance, low cost, compact size, and high dissipation capability. Its output resistance has an average value of 0....
Boost Controller Drives Buck Converter: 02/03/97 EDN Design Ideas / (added 3/05) -- By adding an external Switching Transistor, you can use a step up dc/dc Converter to step down voltages to produce an efficient Battery Powered Power Supply, this example Circuit can step down inputs as Low as2V to Outputs as Low as1.25V, with efficiency as high as 80%
Boost Converter Generates 27 and 87V: 05/22/97 EDN-Design Ideas / (added 3/03) -- Generates the voltage levels necessary for standard telephones from12V
Boost Converter Generates Three Analog Rails #2: 07/02/98 EDN-Design Ideas / (added 3/03) The standard boost converter in Figure 1 uses not only IC1, C1, L1, D1, and C2 to generate a main 5V output, but also additional small, low-cost components to provide two auxiliary supply rails of 10 and -5V. These auxiliary outputs are useful for analog circuitry in small handheld instruments, which often require supply voltages greater than the signal range. Input voltages of 0.8 to 5.5V, which is equivalent to voltages from a battery pack of one to three cells, sustain the main regulated output of 5V±2%. With an input of 1.8V from two flat cells, for instance, and with the other rails unloaded, the circuit can produce 25 mA with 80 to 90% efficiency.
Boost Converter Generates Three Analog Rails: Maxim Application Note #2026 (app note added 7/03) In Figure 1, a standard boost converter consisting of IC1, C1, L1, D1, and C2 generates, in addition to the main output, two auxiliary supply rails (10V and -5V) with the addition of some small and very low-cost extra components. Such rails are useful for the analog circuitry in small handheld instruments, which often require supply voltages in excess of the signal range....
Boost Converter Works with Wide Range Negative Input Supply: 03/18/04 EDN Design Ideas / (added 1/05) Assume that a design requires positive voltage, but only a negative-voltage power source is available. Using a standard boost-converter IC in the circuit of Figure 1, you can efficiently generate a positive voltage from a negative source. The boost converter generates an output voltage that's higher than the input voltage....
Boost Reference Design: This design uses the UCC38C43 as a boost power supply controller. It operates from a 12 volt input and generates a 24 volts (or higher) output voltage. The input voltage can be widely varying as the UCC38C43 can sustain a 20 volt maximum input. (added 3/05)
Boosting Regulator Current: Although the 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant voltage. Currents up to 650mA will flow through the regulator, above this value and the power transistor will start to conduct, supplying the extra current to the load. This should be on an adequate heat sink as it is likely to get rather hot. Suppose you use a 12v regulator, 7812. The input voltage should be a few volts higher to allow for voltage drops. Assume 20 volts. Lets also assume that the load will draw 5amps. The power dissipation in the transistor will be Vce * Ic or (20-12)*8=40watt. It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation. If you want to increase the output current with a negative regulator, such as the 79xx series, then the circuit is similar, but an NPN type power transistor is used instead. (added 7/06)
Bootstrapped Timer: This circuit demonstrates how to use bootstrapping to seriously boost the output power of the timer. The LC555 can only put out about 50mA as it is. This circuit can put out at least 200mA and goes to the rail as well. The LM555 timer puts out 300mA max, but doesn’t go all the way to the rail. Replace Q1 with a big MOSFET, and you can put out big current with these few components. Designed by Andrew R. Morris(added 09/05)
Buck Converter Handles Battery Backup System: 04/24/03 EDN Design Ideas / (added 12/04) A synchronous buck converter is inherently bidirectional. That is, it transfers energy from input to output as a buck regulator when the output voltage is low, but, when the output voltage is high, the converter acts as a boost regulator, transferring power from output to input. This Design Idea shows how to use this bidirectional energy transfer to automatically recharge a battery when the mai......
Buck IC Boosts Battery Voltage for White LED: 04/24/03 EDN Design Ideas / (added 1/05) White-light LEDs are finding their way into many markets that incandescent bulbs once served. Flashlights are among the newer applications in which reliability, ruggedness, and ability to control the power draw of the LEDs make these devices attractive. With incandescent bulbs, the power management for the device is a simple on-off switch....
Build a Charge Pump with UltraLow Quiescent Current: 09/05/04 EDN Design Ideas / (added 1/05) Portable battery-powered devices often spend most of their life in standby mode, in which the quiescent current of an internal boost converter continuously bleeds the battery. The quiescent current during standby can be larger than the actual load current. Though several inductor-based converters offer maximum quiescent current of less than 10 µA, designers usually prefer or require a regu......
Circuit breaker handles Voltages to 32V: 05/25/00 EDN-Design Ideas / (added 2/06) The simplicity of low-side current monitoring can mask the advantages of a high-side approach. You can monitor load currents in a power supply, a motor driver, or another power circuit on either the high or the low side (ground). However, don't let the ease of low-side monitoring cause you to overlook its dangers or the advantages of a high-side approach. Various fault conditions can bypass the low-side monitor, thereby subjecting the load to dangerous and undetected stresses. On the other hand, a high-side monitor connected directly to the power source can detect any downstream failure and trigger the appropriate corrective action. Traditionally, such monitors required a precision op amp, a boost power supply to accommodate the op amp's limited common-mode range, and a handful of precision resistors. Now, the MAX4172 IC can sense high-side currents in the presence of common-mode...
Configure buck converter for boost operation : 12/17/98 EDN-Design Ideas / (added 2/06) Buck converters are inherently different from boost converters, because buck converters typically use the high side of the output as the power switch’s reference. However, a buck converter with a floating output drive section is configurable as a boost controller (Figure 1). This circuit configures the SC1101 buck controller for a 5 to ±12V boost with ±500 mA of output current. The BST pin, which normally connects to a high-side drive supply in a buck converter, connects to VCC to drive the ground-referenced MOSFET. By tying PGND to circuit ground, the SC1101 becomes a boost controller, yielding 12V from 5V. An output charge-pump voltage inverter provides –12V at 0.5A as well....
Controller IC and One Shot Form Resonant Controller: 11/28/02 EDN Design Ideas / (added 1/05) Resonant power supplies are popular because of high efficiency, low noise, and compactness. You can implement a resonant buck or boost converter using a single switch. The regulation of the output in such a converter derives from using a constant on or off time and a variable frequency. The UC1864 controller IC (Texas Instruments, www....
Cutting-Edge Mount Down Methods Boost Power Semiconductor Performance: This paper will evaluate the performance of TO-264 and new T-MAX™ plastic packaged MOSFETs in a variety of mount down situations, both galvanically isolated and electrically hot. Application Note Microsemi-formerly Advanced Power Technology APT9902 (app note added 4/08)
EPLD configures wait-state generator : 02/03/97 EDN Design Ideas / (added 2/06) Using a faster microcontroller or microprocessor in an existing application can boost the performance of a system. Unfortunately, interfacing the faster processor to the much slower existing peripheral ICs is a complex task. To overcome this problem, new processors, such as Philips XA, have an external wait-state-insertion capability. Given this wait-state feature, the tricky part is to generate the wait-state signal itself. In many cases, you can use one-shot ICs, such as the 74HCT221. Unfortunately, these ICs have a slow response time. This Design Idea shows how to build a wait-state generator with a fast response time (5 nsec, typically) using an EPLD. A benefit of using an EPLD is that you can integrate other glue logic, such as address decoding, into the EPLD....
Gate Boost Solar Engine: Voltage-Controlled Solar Engine: The "Gate Boost Solar Engine" is a new (6/2002) Wilf Rigter 1381-based design. This uses an internal voltage doubler to turn on a FET more efficiently. (added 11/05)
Get Just Enough Boost Voltage: 05/27/04 EDN Design Ideas / (added 11/05) Adding a current-mirror circuit to a typical boost circuit allows you to select the amount of boost voltage and to ensure a constant difference between the input and the output voltages (Figure 1). This circuit is useful for high-side-drive applications, in which a simple voltage doubler is unacceptable because of the voltage range of the components involved or where the input voltage can vary ...
Get more Power with a Boosted triode #1: 04/03/03 EDN-Design Ideas / (added 02/05) Even though 6L6 beam-power tubes have been around for 66 years, they are still quite popular for use in electric-guitar amplifiers, and its cousin, the 6CA7 (EL34) power pentode, is a favorite among audiophiles. The developers of these tubes designed them for pentode-mode operation, and they deliver maximum audio power in this mode...
Get more Power with a Boosted triode #2: 06/12/03 EDN Design Ideas / (added 02/05) This Design Idea is a reprint of an earlier one that contained errors in graphics (Reference 1). Even though 6L6 beam-power tubes have been around for 66 years, they are still quite popular for use in electric-guitar amplifiers, and its cousin, the 6CA7 (EL34) power pentode, is a favorite among audiophiles....
High Voltage Amplifier uses simplified circuit: 10/14/04 EDN Design Ideas / (added 5/05) Many scientific instruments and sensors need ac high-voltage drive. High-voltage drive is useful for driving electrodes in many applications. The challenge is to boost the output of a conventional op amp to high voltages. Available ac high-voltage amplifier modules are limited to approximately 1200V p-p.
Bridging enhances filter close-in selectivity: 03/02/00 EDN-Design Ideas / (added 2/06) General filters are bandpass filters that usually employ bridging couplings between nonadjacent interstage couplings (Reference 1). This class of filters also includes bridging coupling across the filter input and output ports. The implementation of input-to-output bridging already exists for a one-pole filter (Reference 2). For a two-pole filter, dielectric resonators help achieve input-to-output bridging coupling (Reference 3)....
Circuit Adds Programmability to Sensor Amplifier: 03/21/02 EDN Design Ideas / (added 12/04) The pressure-sensor amplifier circuit of Figure 1 offers a number of advantages over the traditional approach using the classic three-op-amp instrumentation amplifier. The circuit can operate from a single supply and uses only two op amps and 1% resistors. If the reference voltage, VREF, is 0V, the transducer gain for the circuit isTo ensure equal gain for the two ground-referenced volt... ...
DeltaSigmaADCBridge Measurement Techniques: AN96 - Linear Technology - AN96 features several applications that demonstrate how to take full advantage of Linear Technology's delta sigma ADCs when interfacing to sensors. In many cases, signal conditioning can be greatly simplified or eliminated completely. This note explains where it is appropriate to use amplifiers and how to optimize amplifier gain. Also included are discussions on measuring effective number of bits (ENOB) and the relationship to instrument performance, frequency response of delta sigma ADCs, and test techniques. C source code for all of the applications is included to aid firmware development. (Circuit / schematic design added 6/06)
Programmable Gain Amplifier is Low Cost: 03/17/1994 EDN Design Ideas / (Electronic circuit added 5/02) A programmable reference diode, such as the Motorola TL431A, can supply constant-current bias for a silicon pressure-sensor bridge (Fig 1). This circuit is simpler than using an op amp and separate reference diode or than using a current diode, which requires temperature compensation. The TL431A produces a VREF of 2.5V over a current range of 1 to 100 mA. The value of VREF/R2 sets the necessary bias current for the bridge sensor, as specified by the sensor manufacturer. The reference diode current, set....
Rc Network Eliminates Precision Reference: 08/04/94 EDN Design Ideas / (Electronic circuit added 5/02) The circuit in Fig 1 uses a magneto-resistive sensor to detect small magnet displacements without resorting to a precision voltage reference. A simple RC divider takes the place of the reference, eliminating an expensive component and obviating trimming each circuit....
Miniature FM Spy Mic: This spy mic works from single 1.5 volts AA type battery cell. It is highly sensitive and has a range of 300 meters. You can use any HF transistor with cut-off freq. >300 MHz for Q. Use electret mic. (added 6/06)
Improved Kelvin contacts boost Current sensing accuracy by an order of magnitude: 02/17/05 EDN Design Ideas / (added 5/05) Many power-supply designs rely on accurately sensing the voltage across a current-sense element. Multiphase regulators use the sense voltage to force current sharing among phases, and single-phase regulators to control the current-limit setpoint. As internal complexity and clock speeds increase, processors impose narrower operating margins for power-supply voltages and currents, which in turn m...
Improved Power MOSFETs Boost Efficiency In A 35kw Single Phase Pfc: This paper charts the technological evolution of APT’s powerMOSFETs from the earliest PowerMOS IV designs to the latest PowerMOS 7TM products. The improvement in performance of a 3.5kW boost converter equipped in turn with different generation products is evaluated, as well as the influence of various MOSFET package styles on thermal behaviour and potentially harmful overvoltages. Application Note Microsemi APT0101 ( app note added 4/08)
LED Headlamps : This article includes circuits of DC-DC LED drivers step downs to run LEDs on less than Battery Volts, Boost for above. (added 4/02)
Linear Technology Magazine Circuit Collection Volume IV: AN84 - Linear Technology - Application Note 84 is a collection of "power circuits" from the years 1996 through 1998 as seen in the pages of Linear Technology magazine. This Application Note collects circuits that can output tens of amps to circuits that can operate a handheld device for several years. In addition to a wide variety of traditional power supply circuits (Buck, Boost, Inverting, Flyback, Linear Regulators, etc.) we include circuits for charging batteries, several Power Management circuits as well as circuits that highlight a very low noise switching regulator.
Low cost feedback circuit Boosts efficiency: 01/21/99 EDN-Design Ideas / (added 11/05) To implement a step-up converter with a current output, designers often simply connect the load in place of the top resistor in a resistive-divider feedback network. The bottom resistor then serves as a current-sense resistor. Though simple, this approach is inefficient. Low efficiency results from the relatively high sense voltages—usually, 1.25V but as high as 2.5V for some ICs. A switch-mode dc/dc converter configured as a 20-mA current source minimizes the efficiency loss by lowering the sense voltage to 200 mV (Figure 1). Advantages of this circuit include the factor-of-six gain in efficiency; minimal board area; and readily available, low-cost components. Applications include battery charging, LED drive, and general-purpose current sources....
LT1070 Design Manual: AN19 - Linear Technology - This design manual is an extensive discussion of all standard switching configurations for the LT1070; including buck, boost, flyback, forward, inverting and "Cuk." The manual includes comprehensive information on the LT1070, the external components used with it, and complete formulas for calculating component values.
LT1074/LT1076 Design Manual: AN44 - Linear Technology - This note discusses the use of the LT1074 and LT1076 high efficiency switching regulators. These regulators are specifically designed for ease of use. This application note is intended to eliminate the most common errors that customers make when using switching regulators as well as offering insight into the inner workings of switching designs. There is an entirely new treatment of inductor design based upon simple mathematical formulas that yield direct results. There are extensive tutorial sections devoted to the care and feeding of the Positive Step- Down (Buck) Converter, the Tapped Inductor Buck Converter, the Positive-to-Negative Converter and the Negative Boost Converter. Additionally, many troubleshooting hints are included as well as oscilloscope techniques, soft-start architectures, and micropower shutdown and EMI suppression methods.
LT1339 Design Manual: AN73 - Linear Technology - This application note contains detailed design information to allow the reader to craft switching regulators using the LT1339 high power synchronous DC/DC converter. The note provides expanded pin descriptions for the LT1339 as well as easy-to-use graphical tools for the design of high power synchronous buck and boost converters. The manual includes extensive information on the LT1339 and the external components used with it along with formulas and/or graphics to calculate component values.
Pass Transistor Lowers Dropout Voltage: 02/18/99 EDN-Design Ideas / (added 6/03) With linear regulators,you measure dropout voltage, VIN–VOUT, at the minimum input voltage for which the IC sustains regulation. Low dropout means longer battery life, because the load circuit continues to operate while the battery discharges to a lower terminal voltage. The external transistor helps to form a linear-regulator circuit whose dropout voltage at 100-mA load current is only 10 mV (Figure 1). (The linear-regulator IC by itself specs a 100-mV dropout at 100 mA.) The external transistor also boosts the maximum available load current to 1A....
Photo-flash charger minimizes parts count : 10/22/98 EDN-Design Ideas / (added 2/06) Photo-flash and strobe devices operate by discharging a high-voltage capacitor into a bulb. Charging the capacitor from a battery or other low-voltage source requires a step-up dc/dc converter to boost the voltage, typically to 300V. One way to generate the high voltage is to use a flyback converter. The circuit in Figure 1 provides a simple and reliable way to charge a high-voltage capacitor. The flyback converter performs two functions: It boosts the low-voltage input and provides isolation between the input (battery) and output (high voltage). Its main components are the power transformer; the output diode; the output capacitor; and the MIC3172 controller chip, which combines the switching transistor, voltage regulator, and control logic....
Positive regulator makes dual negative output converter: 06/26/03 EDN Design Ideas / (added 1/05) Some systems, such as optical networks, require more than one negative voltage. A common procedure is to boost the main negative supply of -5V to -10V and then reduce it with a linear regulator to -9V. The -5V itself comes from a positive supply, typically 5 or 12V. Independently creating each of the two negative voltages requires the use of two switching-regulator ICs....
Positive regulator makes negative DC/DC converter: 12/26/02 EDN Design Ideas / (added 1/05) Power-supply designers can choose from a plethora of available positive buck regulators that can also serve as negative boost dc/dc converters. Some buck regulators have a negative-feedback reference voltage expressly for this purpose, but ICs that have positive-reference feedback voltages far outnumber these negative-feedback regulators...
Protection Feature Enhances Boost Converter: 10/27/94 EDN-Design Ideas / (added 2/06) A boost-topology switching regulator is the simplest solution for converting a two- to three-cell input to a 5V output. Unfortunately, boost regulators have several inherent disadvantages, including a lack of short-circuit protection and shutdown capability. In some battery-operated products, external chargers or adapters can raise the battery voltage to a potential higher than the 5V output. Because of this increase, a boost converter can't maintain regulation because the high input voltage feeds through the diode to the output...
Pushbuttons and Digital Potentiometer Control Boost Converter: 02/17/05 EDN Design Ideas / (added 11/05) Digitally controlled potentiometers are useful for generating analog control voltages under the control of a microcontroller. In some applications, manual pushbutton switches could replace a microcontroller and simplify product design. Mechanical switches exhibit contact bounce, and, when a user actuates them, they may open and close many times before reaching a stable state.
PWM Controller Drives LEDs from High Voltage Lines: 03/04/04 EDN Design Ideas / (added 6/06) Powering LEDs from a wide dc range—say, 30 to 380V—without wasting a lot of power in the regulating block, is a difficult task when the LED current needs to be constant. Dedicated LED drivers are available, but they usually implement boost structures and are thus inadequate for high-voltage inputs.
Scheme Provides High Side Current Sensing for White LED Drivers: 02/19/04 EDN Design Ideas / (added 1/05) White LEDs find wide use in backlighting color-LCD screens in most portable devices, such as cellular phones, PDAs, and MP3 players. Multiple LEDs often connect in series to ensure that the same current flows through every LED. To forward-bias these LEDs, a voltage of 10 to 16V comes from an inductor-based boost regulator, such as an SP6690....
SEPIC generates 5V at 100 mA: 05/03/01 EDN-Design Ideas / (added 11/05) / PDF contains multiple circuits - scroll to find the one of interest / Some applications require an input voltage higher than the breakdown voltage of the IC supply pin. In boost converters and SEPICs (single-ended primary-inductance converters), you can separate the VIN pin of the IC from the input inductor and use a simple Zener regulator to generate the supply voltage for the IC. This design shows a SEPIC that takes a4 to28V input and generates5V at100 mA.
Sine wave Step Up converter uses Class E concept: 02/17/05 EDN Design Ideas / (added 6/05) Many power applications ranging from luminescent and fluorescent lighting to telephone-ringing voltage generators require a more or less sinusoidal-drive voltage. These applications typically require a waveform of only moderate quality, and its frequency isn't especially critical. However, avoiding waveform discontinuities that cause unwanted current peaks, excessive device dissipation, and EMC...
Single Transistor provides short circuit protection: 10/16/03 EDN Design Ideas / (added 1/05) In certain dc/dc-converter applications, on-chip, cycle-by-cycle current limit may be insufficient protection to prevent a failure during a short circuit. A nonsynchronous boost converter provides a direct path from the input to the short circuit through the inductor and the catch diode. Regardless of current-limit protection in the IC, when a short circuit exists in the load, extremely high cu......
Step-Up/Step-Down Converter Takes 2 to 16V Inputs: 07/16/98 EDN Design Ideas / (added 11/05) The circuit in Figure 1 is a low-cost step-up/step-down dc/dc converter. By definition, its input can range above and below the regulated voltage. The circuit includes a simple switchmode boost converter (IC1) that contains a comparator normally used to detect low battery voltage. In this case, the comparator controls an external pnp transistor that operates as a linear regulator. IC1 steps up VIN (2V minimum) to the level of VX, as determined by the jumper block, J1.....
Supercapacitor Boosts Current from small Battery: 09/02/04 EDN Design Ideas / (added 1/05) Some battery-powered devices require large amounts of current in a short period of time but spend most of the time in sleep (power-down) mode. The momentary large-load current demands large batteries to meet the time requirement, even though the average current consumption is low. For instance, a system operates for 1....
Supply Derives 5 and 3.3V from USB Port: 12/20/01 EDN Design Ideas / (added 12/04) The circuit in Figure 1 derives its power from a USB port and produces 5 and 3.3V supply rails for portable devices, such as digital cameras, MP3 players, and PDAs. The circuit allows the port to maintain communications while, for example, charging a lithium-ion battery. IC2 boosts the battery voltage, VBATT, to 5V, and IC3 buck-regulates that 5V output down to 3. ...
Three input supply powers 3.3V portables: 04/13/95 EDN-Design Ideas / (added 6/06) The single-ended primary-inductance converter in Fig 1 accepts input voltages ranging from 3 to more than 6V and produces a regulated 3.3V, 200-mA output. The converter accepts an input voltage from three sources: a 5V dc wall cube, a three-cell AA battery, and a lithium backup battery. Unlike conventional boost regulators whose battery current continues to flow during shutdown (unless you add a cutoff switch), this circuit's output turns off fully in response to a shutdown command. And, unlike flyback-transformer regulators and combination step-up/linear regulators, Fig 1 requires no transformers. Coils L1 and L2 should be the same type and have the same value, but coupling between them isn't required. You can wind the inductors on the same core for convenience, but the circuit works equally well if they are completely separate....
Three parts provide tenfold increase in Switcher Current: 08/22/02 EDN Design Ideas / (added 1/05) Industrial-control circuits often derive their power from widely varying sources that can exceed the 40V maximum rating of popular switching ICs. This Design Idea presents a simple, flexible, and inexpensive buck switcher that converts an input voltage as high as 60V to 5V at several amps. The circuit is unique in that it boosts current with almost no compromise in performance, size, or cost....
Three-Band Equalizer: Using a single op-amp this easy to make equalizer offers three ranges, low frequency, mid frequency, and high. With component values shown there is approximately +/-20dB of boost or cut at frequencies of 50Hz, 1kHz and 10kHz. Supply voltage may be anything from 6 to 30 Volts. Maximum boost 20dB is only realized with maximum supply voltage. (added 4/05)
TPS61042 White Light LED Driver Boost Converter (Rev. A): TI Application Note (added 6/06)
UCC3819 250-W Pfc Boost Follower Preregulator Design: This is an application note that describes a reference design.This paper reviews the benefits of a boost follower topology and the design of a 250-W PFC boost follower preregulator. (added 3/05)
Unique IC Buffer Enhances Op Amp Designs Tames Fast Amplifiers: AN16 - Linear Technology - This note describes some of the unique IC design techniques incorporated into a fast, monolithic power buffer, the LT1010. Also, some application ideas are described such as capacitive load driving, boosting fast op amp output current and power supply circuits.
Universal PSU: A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps. (added 7/06)
Use a Microcontroller to Design a Boost Converter: 03/04/04 EDN Design Ideas / (added 1/05) Boost converters, like other switchers, have traditionally received their control signals from a dedicated circuit. However, a recent trend is to integrate simple switching-power-supply building blocks into generic devices, such as microcontrollers. An excellent example of this concept is a microcontroller that combines digital and analog circuitry and makes it easier to build simple power supp......
Buck regulator and two inductors make dual Polarity converter: 03/20/03 EDN Design Ideas / (added 1/05) A common problem for power-supply designers is to create a compact, dual-polarity step-down converter. If space and cost are not concerns, the obvious solution is a pair of dc/dc converters, one for each output. But space and cost are almost always issues for communications, data-acquisition, and disk-drive applications....
Buck regulator forms high Power inverting5V supply: 04/01/04 EDN Design Ideas / (added 1/05) Configuring a step-down switching-converter IC as an inverter yields an efficient, high-power, -5V supply that can of deliver currents as high as 4.5A at the 12V input or 3.2A at the 5V input (Figure 1). Conventional inverting power supplies do their switching using a p-channel MOSFET (Figure 2). That configuration works well at lower currents, but has limited use above approximately 2A, depend......
Buck Regulator Generates Flexible VTT for PECL: 08/15/97 EDN Design Ideas / (added 07/02) -- Circuit to generate Output which can both Source and Sink Current -- The positive emitter-coupled logic (PECL) in most high-speed clock-distribution and -recovery circuits requires a termination voltage, VTT, that imposes special requirements on the VTT supply. First, the typical switching thresholds for PECL must refer to VDD instead of ground (VOL=VDD1.32V+400 mV, and VOH=VDD1.32400 mV). The level of VTT, typically at VDD2V, is slightly below VOL to ensure that the open-emitter outputs always source current (Figure 1a). Unlike most power-supply voltages, therefore, the supply must regulate VTT with respect to VDD instead of ground....
Buck regulator operates Without a dedicated clock: 08/21/03 EDN Design Ideas / (added 1/05) Most switching regulators rely on a dedicated clock oscillator to determine the switching frequency of operation. A dedicated oscillator circuit within the power controller usually generates the clock signal. A class of hysteretic switching regulators can actually operate at a relatively fixed frequency without a clock, even with changing input-line and output-loading conditions....
Buck/Boost Reference Design: This reference design presents an alternative to the typical boost power regulator. A buck converter IC is used to generate a higher voltage needed by the white light LED power from a Ni-Cd battery. This circuit operates by turning the high switch on, connecting the battery voltage across the inductor. Once sufficient energy is stored in the inductor, the high side switch is turned off. The inductor current drives the switching node negative and energy is delivered through the low side into the output capacitor. This is essentially a lossless switching event. Also, since the high side and low side switches are MOSFET's, voltage drop can be very low as compared to a diode implementation so efficiency can be high. Regulation is achieved by monitoring the current through the LED with a current sense resistor and comparing it to an internal 0.45 volt reference within the converter IC. Current and thereby, illumination is varied by modifying the current sense resistor voltage. (added 3/05)
Capacitor Improves Efficiency in CPU Supply: 04/04/02 EDN Design Ideas / (added 3/05) High efficiency is important for the dc/dc buck converters that supply high currents in notebook PCs. This efficiency extends battery life and minimizes temperature rise. A low-dissipation synchronous rectifier using an external MOSET provides this high efficiency. Synchronous rectifiers require special attention, however. ...
Cheap PWM IC Makes Synchronous Gate Driver: 02/04/99 EDN-Design Ideas / (added 6/06) A system with a µP, memory, and peripherals usually requires several power-supply voltages. Designers typically use local switching regulators to produce the desired voltage rails. One of the most common topologies, the synchronous buck regulator, converts a 5 or 12V bus to some other, lower voltage. This approach...
Configure buck converter for boost operation : 12/17/98 EDN-Design Ideas / (added 2/06) Buck converters are inherently different from boost converters, because buck converters typically use the high side of the output as the power switch’s reference. However, a buck converter with a floating output drive section is configurable as a boost controller (Figure 1). This circuit configures the SC1101 buck controller for a 5 to ±12V boost with ±500 mA of output current. The BST pin, which normally connects to a high-side drive supply in a buck converter, connects to VCC to drive the ground-referenced MOSFET. By tying PGND to circuit ground, the SC1101 becomes a boost controller, yielding 12V from 5V. An output charge-pump voltage inverter provides –12V at 0.5A as well....
Constant on Time Buck Boost Regulator Converts a Positive Input to a Negative Output: 12/07/04 EDN Design Ideas / (added 11/05) Buck regulators find wide application as step-down regulators for converting large positive input voltages into a smaller positive output voltages. Figure 1 shows a simplified buck regulator that operates in continuous-conduction mode—that is, the inductor current always remains positive. The output voltage, VOUT, is equal to D×VIN, where D is the duty-cycle ratio of the buck switc...
Controller IC and One Shot Form Resonant Controller: 11/28/02 EDN Design Ideas / (added 1/05) Resonant power supplies are popular because of high efficiency, low noise, and compactness. You can implement a resonant buck or boost converter using a single switch. The regulation of the output in such a converter derives from using a constant on or off time and a variable frequency. The UC1864 controller IC (Texas Instruments, www....
Surveillance Transmitter Detector: This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable a detector is to get its sensitivity just right, Too much sensitivity and it will respond to radio broadcasts, too little, and nothing will be heard.
Add an auxiliary Voltage to a Buck regulator: 10/31/02 EDN Design Ideas / (added 1/05) You often need more than one regulated output voltage in a system. A frequently used and reasonably simple way to create this auxiliary output voltage is to add a second winding to the output inductor, creating a coupled inductor or a transformer, followed by a diode to rectify (peak-detect) this output voltage....
Buck/Boost Reference Design: This reference design presents an alternative to the typical boost power regulator. A buck converter IC is used to generate a higher voltage needed by the white light LED power from a Ni-Cd battery. This circuit operates by turning the high switch on, connecting the battery voltage across the inductor. Once sufficient energy is stored in the inductor, the high side switch is turned off. The inductor current drives the switching node negative and energy is delivered through the low side into the output capacitor. This is essentially a lossless switching event. Also, since the high side and low side switches are MOSFET's, voltage drop can be very low as compared to a diode implementation so efficiency can be high. Regulation is achieved by monitoring the current through the LED with a current sense resistor and comparing it to an internal 0.45 volt reference within the converter IC. Current and thereby, illumination is varied by modifying the current sense resistor voltage. (added 3/05)
Buck/Boost Regulator Suits Battery Operation: 09/04/03 EDN Design Ideas / (added 1/05) A buck/boost converter can step a voltage up or down. Such a converter is appropriate for battery-powered applications. One application derives a regulated 14.1V at 1A from 12V solar panels with 9 to 18V variation. In this type of battery application, efficiency is an important factor; hence, this design uses an inexpensive synchronous-rectifier-based MC33166/7 circuit....
Constant on Time Buck/Boost Regulator Converts a Positive Input to a Negative Output: 12/07/04 EDN Design Ideas / (added 11/05) Buck regulators find wide application as step-down regulators for converting large positive input voltages into a smaller positive output voltages. Figure 1 shows a simplified buck regulator that operates in continuous-conduction mode—that is, the inductor current always remains positive. The output voltage, VOUT, is equal to D×VIN, where D is the duty-cycle ratio of the buck switc...
Get Buck/Boost Performance from a Boost regulator: 07/11/02 EDN Design Ideas / (added 1/05) The SEPIC (single-ended, primary-inductance-converter) topology is generally a good choice for voltage regulators that must produce an on output voltage that falls in the middle of the input-voltage range, such as a 5V output from a 2.7 to 6V input, The topology has some disadvantages, however. The efficiency of a SEPIC circuit fares worse than that of buck and boost regulators, and SEPIC desig......
LDO Buck/Boost 2 Sync Buck Sync Boost Reference Design: LDO, Buck/Boost, 2 Sync. Buck, Sync. Boost with Vin 2.7-4.2 V LiION or 4.5-6.5 V adapter. Multiple output voltages of 1.5 V, 2.5 V, 3.3 V and 8 V. The total output power is 5.5 W. (added 3/05)
Step Up/Step Down Current Source Charges Batteries: 06/06/96 EDN Design Ideas / (added 11/05) For battery charging, the highly efficient step-down (buck) configuration is usually the topology of choice. However, a different approach is necessary if the following conditions prevail: The supply voltage is less than the battery voltage, or, even worse, the supply voltage ranges above and below the battery voltage.
Synchronous Buck Reference Design #2: This reference design is synchronous Buck/Boost converter that can deliver up to 3.8 A of continuous current at -5 V from a 5 V input. This topology uses a synchronous buck controller (TPS5103) referenced to the negative output rail. The synchronous MOSFETs allow this design to achieve a peak efficiency of 88%. In addition, the TPS5103 provides a soft-start function and over-current protection. (added 3/05)
3.3V converter delivers 3W from Li-ION battery : 11/05/98 EDN-Design Ideas / (added 11/05) Lithium-ion batteries are rapidly gaining popularity in portable applications because of their superior energy density, low self-discharge rate, and high cell voltage. When you use one Li-ion battery to power a 3.3V dc/dc converter; however, you encounter a problem, because the battery voltage can be higher or lower than 3.3V. When fully charged, a Li-ion cell has approximately 4.2V output; when fully discharged, the voltage is approximately 2.5V. Therefore, you cannot use a simple buck or boost topology with a single inductor to generate a regulated 3.3V output. Some designs boost the voltage to approximately 4.3V and then use a low-dropout regulator to produce the 3.3V. This approach is inefficient, and efficiency is a crucial consideration in battery-powered applications. The circuit in Figure 1 offers a solution to the problem....
Add an auxiliary Voltage to a Buck regulator: 10/31/02 EDN Design Ideas / (added 1/05) You often need more than one regulated output voltage in a system. A frequently used and reasonably simple way to create this auxiliary output voltage is to add a second winding to the output inductor, creating a coupled inductor or a transformer, followed by a diode to rectify (peak-detect) this output voltage....
AN-H48: Buck-Based LED Drivers using the HV9910: Supertex Semiconductors (app note added 6/06)
Boost Controller Drives Buck Converter: 02/03/97 EDN Design Ideas / (added 3/05) -- By adding an external Switching Transistor, you can use a step up dc/dc Converter to step down voltages to produce an efficient Battery Powered Power Supply, this example Circuit can step down inputs as Low as2V to Outputs as Low as1.25V, with efficiency as high as 80%
Buck Boost Regulator Suits Battery Operation: 09/04/03 EDN Design Ideas / (added 1/05) A buck/boost converter can step a voltage up or down. Such a converter is appropriate for battery-powered applications. One application derives a regulated 14.1V at 1A from 12V solar panels with 9 to 18V variation. In this type of battery application, efficiency is an important factor; hence, this design uses an inexpensive synchronous-rectifier-based MC33166/7 circuit....
Buck Configuration High-Power LED Driver: Microchip Application Note - Published 4-Jan-06 (app note added 6/06)
Buck Converter Chargers also Provides System Power: 05/22/97 EDN Design Ideas / (added 4/02) -- Switching Regulator provides the charge voltage setpoint with Current regulation, and second Switching Regulator provides5V System Power -- Many systems require long-time operation during periods of power loss. Often, a gel or wet-cell lead-acid battery is the best choice because of high capacity and relatively low cost. The battery charges during normal operation and powers the system during power loss. These systems require a circuit to charge the battery as well as to regulate the system's VCC. The design must provide a current-limited voltage to the battery for charging and still develop system VCC in the charge or the discharge condition.....
Buck Converter Handles Battery Backup System: 04/24/03 EDN Design Ideas / (added 12/04) A synchronous buck converter is inherently bidirectional. That is, it transfers energy from input to output as a buck regulator when the output voltage is low, but, when the output voltage is high, the converter acts as a boost regulator, transferring power from output to input. This Design Idea shows how to use this bidirectional energy transfer to automatically recharge a battery when the mai......
Buck IC Boosts Battery Voltage for White LED: 04/24/03 EDN Design Ideas / (added 1/05) White-light LEDs are finding their way into many markets that incandescent bulbs once served. Flashlights are among the newer applications in which reliability, ruggedness, and ability to control the power draw of the LEDs make these devices attractive. With incandescent bulbs, the power management for the device is a simple on-off switch....
Buck Reference Design: This reference design is a buck converter that can deliver up to 2A of continuous current at -24 V from an input range of -35 V to -75 V. By referencing the UCC3813 controller to the negative input rail, the N-channel MOSFET is easily driven. This design achieves a peak efficiency greater than 95%. The UCC3813 provides current mode control for excellent line and load transient response. (added 3/05)
Double Data Rate Power Supply using the Tl5002 Voltage Tracking Regulator: The TL5002EVM-180 synchronous buck converter provides a 12A reference design for evaluating the performance of the TL5002 PWM control IC and the TPS2837 MOSFET driver for Double Data Rate (DDR) memory applications. (added 3/05)
Dual High-Current Power Supply Kit: The National Semiconductor Power Supply Kit is designed around the National LM2636, a synchronous buck regulator. It provides over 28 amps of current with variable output voltages ranging from +1.3V to +3.3V. (added 3/05)
EP48 12 V 1.44 W Non-Isolated Buck Converter: This design kit is a non-isolated 12 V, 120 mA power supply utilizing a LNK304. This power supply is intended as a general purpose evaluation platform for LinkSwitch-TN in a buck converter configuration. (added 7/06)
Extend the input range of a Low dropout regulator: 10/17/02 EDN Design Ideas / (added 1/05) Because of process limitations, all ICs have an input-voltage limitation. This limitation can be cumbersome when you try to step down a high supply voltage to a lower, regulated voltage using a dc/dc converter, such as a linear regulator. Adding a FET to the input of a linear regulator creates a dc/dc converter with a wider input-voltage range than the range of the regulator alone....
Flyback LDO Buck Sync. Buck Reference Design: Flyback, LDO, Buck and Sync Buck with Vin 10 to 16 V. Multiple output voltages of -24 V, -5 V, 1.5 V, 3.3 V, 5 V, 12 V and 58 V. The total output power is 15 W. (added 3/05)
Get Buck boost Performance from a Boost regulator: 07/11/02 EDN Design Ideas / (added 1/05) The SEPIC (single-ended, primary-inductance-converter) topology is generally a good choice for voltage regulators that must produce an on output voltage that falls in the middle of the input-voltage range, such as a 5V output from a 2.7 to 6V input, The topology has some disadvantages, however. The efficiency of a SEPIC circuit fares worse than that of buck and boost regulators, and SEPIC desig......
LDO Buck/Boost 2 Sync Buck Sync Boost Reference Design: LDO, Buck/Boost, 2 Sync. Buck, Sync. Boost with Vin 2.7-4.2 V LiION or 4.5-6.5 V adapter. Multiple output voltages of 1.5 V, 2.5 V, 3.3 V and 8 V. The total output power is 5.5 W. (added 3/05)
LED Buck PFM: Powers LED with Constant Current Starting at 100MV over VF: This is a proof of concept circuit which needs improvement. The part values shown will run a high efficiency red LED with a Vf of 1.9V from only 2 nicads, right down to 2 volts. For a white LED you will need more batteries and you must increase the 1.0K resistor to a higher value. Current sensing at a mere 18mV over 1ohm makes this stepdown switcher efficient, but efficiency can be increased by using a larger inductor, improving transistor switching speed, or by increasing the value of the 1.0K resistor. ... (added 2/05)
LED Headlamps : This article includes circuits of DC-DC LED drivers step downs to run LEDs on less than Battery Volts, Boost for above. (added 4/02)
Lower DC/DC Converter Ripple by using Optimum Capacitor Hookup: 10/31/02 EDN Design Ideas / (added 3/05) Low-ripple-voltage positive-to-negative dc/dc converters find use in many of today's high- frequency and noise-sensitive disk drives, battery-powered devices, portable computers, and automotive applications. Like a positive buck converter, a positive-to-negative converter can have low output-ripple voltage if you place the bulk input capacitor between VIN and VOUT rather than between VIN and gr......
LT1074/LT1076 Design Manual: AN44 - Linear Technology - This note discusses the use of the LT1074 and LT1076 high efficiency switching regulators. These regulators are specifically designed for ease of use. This application note is intended to eliminate the most common errors that customers make when using switching regulators as well as offering insight into the inner workings of switching designs. There is an entirely new treatment of inductor design based upon simple mathematical formulas that yield direct results. There are extensive tutorial sections devoted to the care and feeding of the Positive Step- Down (Buck) Converter, the Tapped Inductor Buck Converter, the Positive-to-Negative Converter and the Negative Boost Converter. Additionally, many troubleshooting hints are included as well as oscilloscope techniques, soft-start architectures, and micropower shutdown and EMI suppression methods.
Notebook Power Supply has Two Outputs: 03/03/94 EDN-Design Ideas / (added 3/06) The notebook-computer supply in Fig 1 powers the 5V logic and derives an adjustable -24V supply for an LCD's backplane. The design uses only a high-efficiency buck regulator (Si9150) and an NMOS/PMOS, dual-power-FET chip set (Si9943), eliminating the extra parts required when you implement both supplies independently. Because of the low on-resistances of the dual FETs, this circuit can achieve better than 92% efficiency at 7.2V input and full-load output (7.6W)....
