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Last Updated: December 07, 2017 02:04 PM

Circuits Designed by Dave Johnson, P.E. :

 Ultra Low Power Human Finger Detector - The circuit below seems to work well and averages a current drain of only 10 microamps from a lithium cell.  It uses a single CA4013 dual D flip/flop.  One section is wired as a pulse generator.  It applies 10us 10ma pulses to a LED inside a slotted optical sensor at a rate of about 50Hz.  The phototransistor in the second half of the sensor detects the pulses and sends a pulse to the data input of the second flip/flop in the 4013 package.  If there is nothing between the LED and the phototransistor, the inverting output of the 4013 remains low.Circuit Solution by David A. Johnson P.E.-May, 2006

 Ultra Pure 125kHz Sine Wave Signal Source - For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  The circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01%. . . Circuit by David A. Johnson P.E.-February, 2002

 Very Low Power Astable Multivibrator - This classic circuit draws only 200 nanoamps from a 1.5v supply. . . Circuit by Dave Johnson P.E.-June, 2000

 Very Low Power Gated Crystal Oscillator - The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed.  The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed. . . Circuit by David Johnson P.E.-June, 2000

 Voltage Boost to Series Regulator provided by Capacitor - This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range.  It can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply . . . Hobby Circuit designed by David Johnson P.E.-January, 1998

 Voltage Converters-0.5 to 6 Volts - Conventional silicon transistors just can't operate at voltages less than about 0.7v.  Old germanium transistors could be used, but those are hard to find these days and most are rather large in size.  Some new n-channel MOSFET devices with very. . . Circuit by Dave Johnson P.E.-May, 2007


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

UCC3809 Evaluation Module -  The UCC3809EVM evaluation module is an isolated 10-W, 3.3 -V converter designed for telecom input voltages, nominally -48 Vdc, but ranging from -32 Vdc to -75 Vdc.  The UCC3809 economy primary-side controller is used as the pulse-width modulator (PWM) , combined with a TLV431 low-voltage adjustable-precision shunt regulator on the secondary side__ 

UCC3819 250-W Pfc Boost follower Preregulator Design -  This is an App 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.  __ 

Ultra Low Power Human Finger Detector -  The circuit below seems to work well and averages a current drain of only 10 microamps from a lithium cell.  it uses a single CA4013 dual D flip/flop.  One section is wired as a pulse generator.  it applies 10us 10ma pulses to a LED inside a slotted optical sensor at a rate of about 50Hz.  The phototransistor in the second half of the sensor detects the pulses and sends a pulse to the data input of the second flip/flop in the 4013 package.  if there is nothing between the LED and the phototransistor, the inverting output of the 4013 remains low.Circuit Solution by David A. Johnson P.E.-May, 2006

Ultra Pure 125kHz Sine Wave Signal Source -  For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  The circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01%. . . Circuit by David A. Johnson P.E.-February, 2002

Ultra Simple Circuit Split DC Supply -  DC voltage "virtual earth" circuits __ Designed by Rod Elliott  ESP

Ultra-Low Power High Efficiency DC/DC Converter Operates Outside the Audio Band -  DN86 Design Notes__ Linear Technology/Analog Devices

Ultra-Low Quiescent Current AF Power Amplifier -  This is an audio power amplifier, similar to what is common in transistor radios and other portable audio equipment.    This circuit however, has an ultra-low quiescent current of about 250uA, due to a unique bias circuit.  I don’t even know of a chip that d __ Designed by Andrew R. Morris

Ultralow-EMI, 96W, Step-Down μModule Regulator— EN55022 Class B Certified in a 15mm x 15mm Footprint -  The LTM4613 delivers high output power and efficiency with demonstrated EMi performance that complies with EN55022 Class B.  With carefully designed integrated filter, meticulous internal layout, shielded inductor, internal snubber circuitry and power transistor driver, the LTM4613 achieves a perfect __ Linear Technology/Analog Devices App Note, Jan 30, 2012

Unique High Efficiency 12V Converter Operates with Inputs from 6V to 28V -  DN233 Design Notes__ Linear Technology/Analog Devices

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.  __ Linear Technology/Analog Devices

Universal DC-to-DC Converter -  This circuit will generate a smaller DC output voltage from a larger DC input voltage.  it is quick and simple to make and by changing the value of the zener diode, the circuit can be universally adapted to provide other output voltages.  The circuit and all diagrams represent a DC convertor with 12V battery input and 9Volt DC output __ Designed by Andy Collison

Universal Input 48W PFC Application -  The LT3798 is a constant voltage/constant current isolated flyback controller that combines active power factor correction (PFC) with no opto-coupler required for output voltage feedback into a single-stage converter.  A LT3798 based design can achieve a power factor of greater than 0.97 by actively modulating the input current, __ Linear Technology/Analog Devices App Note, Dec 5th 2011

Universal Power Supply -  Linear regulators like LM317, LM337, 78xx and 79xx, Zener diodes (1.3W) and reference diodes (e.g., LM336) are quite inexpensive and widely available.  So you can use these liberally in power supplies.  Sometimes...__ Electronics Projects for You

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.   __ Designed by Volker Jeschkeit

Universal PWM Driver -  PWM drivers are used in analysing, testing, installing and powering all kinds of electronic and electrical devices.  We have published a few designs in Elektor over the years: here we present a ‘de luxe’ version.  must register on this site __ Designed by Published in Elecktor July/Aug, 2010

USB-GSM application with 5V USB input (500mA max) charging a 4.4mF super cap (3.4V at 800mA) & providing 1.8V at 400mA  -  The LTC3619 is a Dual 400mA/800mA monolithic synchronous buck regulator with an input supply voltage range is 2.5V to 5.5V, making it ideal for Li-ion and USB powered applications __ Linear Technology/Analog Devices App Note, Mar 23, 2010

Use a 555 timer as a switch-mode power supply -  14-Nov-02 EDN Design Ideas:  Most switch-mode power supplies rely on a PWM (pulse-width-modulated] output that is controlled via voltage feedback.  A 555-timer IC can inexpensively perform PWM.  The circuit in Figure 1 shows how to turn a 555 PWM circuit into an switch-mode power supply with only one simple equation.  The design uses two 555s __ Circuit Design by Aaron Lager, Masterwork Electronics, Rohnert Park, CA

Use a Boost Regulator Beyond Its Rated Voltage -  01/05/12  EDN Design Ideas:  Use an external FET in a common-gate cascode configuration.  inexpensive boost regulators with on-chip FET power switches work well for low-voltage boost converters, SEPiCs (single-ended primary-inductance converters) , and flyback converters.  For higher voltages, designers typically use a more expensive approach comprising a controller with an external FET or a high-voltage boost regulator.   __ Circuit Design by Kevin Tompsett, Analog Devices, Fort Collins, CO

Use a microcontroller to Design a boost converter -  4-Mar-04 EDN Design Ideas:  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 __ Circuit Design by Ross Fosler, Microchip Technology, Chandler, AZ

Use the Built-In Measurement Capability of Power Sources & Loads -  Application Note__ Aligent

Use Two Phases to Cut Current & Improve EMI -  11/12/09 EDN Design Ideas:  in DC/DC-converter applications in which the input voltage may be lower or higher than the output voltage, you can use either a flyback converter or a SEPiC (single-ended-primary-inductor converter).  SEPiCs offer lower input-curre __ Circuit Design by Goran Perica, Linear Technology, Milpitas, CA

Using a PC power supply as a benchtop power supply -  This ATX PS board has leads for +5 (RED) , -5 (WHiTE) , +12 (YELLOW) , -12 (BLUE) volts, Ground (BLACK) and switch (GREEN).  Dell power supplies manufactured between 1996 and 2000 do not follow the industry standard pinout and color codes.  The fan has also been unplugged for better viewing.  Since this PS was converted for use in the logic and robotics labs, the selected voltages  __ Designed by Andy Batts

Using an AVR -  Tiny13V microcontroller as step up (boost) or step down (buck) voltage converter for driving a white or high power LED. (pdf file) LED headlamp projects. __ Designed by Steven "Melt Solder" Weber  KD1JV

Using the DS4412 to Margin the Output Voltage of a DC-DC Converter  -  App Note 4197-- 3/20/2008 -- (add 5/08) __ Maxim Integrated

Variable DC Power Supply -  Voltage range: 0.7 - 24V; Current limiting range: 50mA - 2A __ Contact Flavio Dellepiane, fladello @ tin.it

Variable Voltage Regulator -  As Ron suggests, controlling the output voltage from a regulator can be made variable in three ways __ Designed by Ron J.

Variations Produce Negative Voltages -  09/01/00 EDN Design Ideas:  Basic switched-capacitor converters generally provide one simple conversion.  They commonly double, usually invert, and sometimes halve a positive input voltage.  Because they are not regulated converters and do not have stability problems, you can easily configure them to also do some negative conversions.  However, given that they are unregulated, it is a good idea to use a regulated input voltage to obtain a predictable output.  All these converters suffer from some voltage change on the output as a result of loading, but this voltage drop is often acceptable.  The potential space and cost savings are often worth the trade-off if the circuit fits the application needs.  Figure 1 and Figure 2 present two application circuits.   __ Circuit Design by Clinton Jensen, National Semiconductor Corp, Santa Clara, CA

Versatile Dc-DC Converter -  Here is a versatile power coupler that connects a device to 5V-19V DC generated from AC mains by a power adaptor.  Power adaptors come in different voltage outputs like 5V (for...__ Electronics Projects for You

Very Low Power Astable Multivibrator -  This classic circuit draws only 200 nanoamps from a 1.5v supply. . . Circuit by Dave Johnson P.E.-June, 2000

Very Low Power Gated Crystal Oscillator -  The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed.  The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed. . . Circuit by David Johnson P.E.-June, 2000

VFD (Vacuum Fluorescent Display) & Filament Power Supply -  The LT3581 is a PWM DC/DC converter with built-in fault protection features to aid in protecting against output shorts, input/output overvoltages, and overtemperature conditions.  The part consists of a 42V master switch, and a 42V slave switch that can be tied together for a total current limit of 3.3 A.  __ Linear Technology/Analog Devices App Note, Jan 16th 2012

VFD (Vacuum Fluorescent Display) Flyback Power Supply -  The LT3758 is a wide input range, current mode, DC/DC controller which is capable of generating either positive or negative output voltages.  it can be configured as either a boost, flyback, [Linear Technology, SepiC or inverting converter.  The LT3758 drives a low side external N-channel power MOSFET from an internal regulated 7.2V supply.  The__ Linear Technology/Analog Devices App Note, Jan 16th 2012

Video Design Idea: Buck regulator controls white LED with optical feedback -  10/25/07  EDN-Video Design ideas - By using optical feedback, you can stabilize the output level of a high-intensity LED __ Circuit Design by Dhananjay V Gadre, Netaji Subhas Institute of Technology, New Delhi, India

Virtual-Zener Simplifies High-Voltage Interface -  03/20/03  EDN Design Ideas:  Buck regulator and two inductors make dual-polarity converter - This design for a photonic switch needsthan approximately 70V at the cathode of a duo-lateral optical position-sensing device.  This voltage gets speedy response at lo __ Circuit Design by Philip Lane, Transparent Networks Inc, Bellevue, WA

Voltage Boost to Series Regulator provided by Capacitor -  This circuit adds some capacitors and diodes to a traditional transformer type series regulator circuit to extend the normal operating range.  it can insure regulation during low line voltage conditions or it can squeeze a few more watts out of a plug-in-the-wall power adapter power supply . . . Hobby Circuit designed by David Johnson P.E.-January, 1998

Voltage Booster (Very Simple) -  Uses a LT1372 and only a Few parts - But can handle 1.5 amps input Current.  input as low as 3 Volts - Output may be as high as 35 Volts __ Designed by G.L. Chemelec

Voltage Converters-0.5 to 6 Volts -  Conventional silicon transistors just can't operate at voltages less than about 0.7v.  Old germanium transistors could be used, but those are hard to find these days and most are rather large in size.  Some new n-channel MOSFET devices with very. . . Circuit by Dave Johnson P.E.-May, 2007

Voltage Inverter IC Forms High Efficiency Rail Splitter -  App Note #218__ Maxim Integrated

Voltage Inverter II -  This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input.  it is therefore extremely useful for powering OpAmp and other circuits that require a dual voltage from a single battery.  The circuit will operate at an input voltage from around 5V to 20V and produce a output from +-2.5V to +-10V. __ Contact IQ Technologies

Voltage Multiplier -  A collection of simple but useful circuits made with silicon diodes.  Scroll to find the voltage multiplier circuit.   __ Designed by Jose Pino

Wall-cube DC/DC converter is 85% efficient -  09/12/97 EDN Design Ideas:  Ubiquitous12V wall cube generates an unregulated dc voltage of 8 to18V, depending on line voltage and load, this circuit generates a regulated5V400 mA from it very efficiently __ Circuit Design by Steve Pietkiewicz, Linear Technology Corp, Milpitas, CA

Wide Input Range, 3.3V SEPIC Converter Can Operate from 3V to 36V (Cold Crank) -  While requiring 6V to start up, the addition of a diode tied from output to input allows this circuit to operate as the battery sags all the way down to 3V.  This wide input voltage range is required for automotive cold crank applications.  The LT3581 is a PWM DC/DC converter with built-in fault protection features to aid__ Linear Technology/Analog Devices App Note, Jul 27th 2010

Wide VIN Range Step-Down Regulators Consume Only 2.8μA Input Current -  Battery life is paramount in modern battery-powered systems.  portable applications, such as remote sensors, require voltage regulators which have low current standby states and also able to provide bursts of high power.  Linear Technology’s LT®3970/LT3971 lead the industry in low current standby mode by consuming only __ Linear Technology/Analog Devices App Note, John Gardner-Design Engineer Power Products May 23, 2011

Wide-range regulator Delivers 12V, 3A output from 16 to 100V source -  06/23/05  EDN Design Ideas:  Buck regulator tackles high input voltages __ Circuit Design by Wayne Rewinkel, National Semiconductor, Schaumburg, IL

World’s First Dual 12-Bit DACs in SO-8 LTC1446/LTC1446L -  DN131 Design Notes__ Linear Technology/Analog Devices

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