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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E. :

Medium Power 125khz Oscillator - This circuit adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz. . . Circuit by Dave Johnson P.E.-March, 2002

 Medium Power 125khz Oscillator #2 - This circuit is similar to MEDIUM POWER 125KHZ OSCILLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz.. . . Circuit by David A. Johnson P.E.-March, 2002

 Micro Power Over-Temperature Alarm - The circuit is powered for years by a single 3 volt lithium battery.  It sounds an alarm when the temperature exceeds a certain point.  With some minor changes the circuit could also be configured for an under temperature (freeze) alarm.  The circuit uses a. . . Circuit by David Johnson P.E.-June, 2000

  Negative 0.5 Volt Supply - This simple circuit consists of two LEDs and a photo diode.  It generates a negative voltage with a current level of a couple milliamps.  It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.  Note:  This circuit is not particularly efficient . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

 Over-Temperature Micro-Power Alarm - The circuit is powered for years by a single 3 volt lithium battery.  It sounds an alarm when the temperature exceeds a certain point.  With some minor changes the circuit could also be configured for an under temperature (freeze) alarm.  The circuit uses a . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

 Peak to Peak 300v Signal Generator - This circuit converts a square wave signal to a +-150 volt output signal with fast 100nS rise and fall times . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000

 RS-232 Serial Interface Status Indicator Circuit - I designed this circuit many years ago and have used it several times since.  It uses a single logic IC to indicate the TXD and RXD line activity of a typical RS-232 serial data communications link.  The thresholds are set at plus 3 volts and minus 3 volts.  Two dual color LEDs are used as indicator lights . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2007


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

Make your own LED Headlamp -  i have submitted here my process for constructing an LED headlamp.  I originally attempted to fit the battery holders for 3 AAA cells along with a tiny PC board for the three LEDs and current limiting resistor all in a tiny altoids tin.  No go.  I ended up buying a 3 cell holder with switch from Mouser electronics, gluing an elbow/ball joint pivot from a desktop pen set I had pieces from to that battery holder, then bolting the pivot to a Walgreens tiny mint tin (the sugar free ones come in a small oval shaped tin).  The LEDs  __ Designed by John Evans

Making Voltage Doublers & Multipliers -  Find out how to construct an AC voltage doubler circuit.  Extend it to a tripler circuit and more.   __ Designed by REUK-Renewable Energy UK website

Measuring self resonant frequency -  Coilcraft RF Magnetics App Note- __ Designed by Coilcraft Power Magnetics Application Note

Measuring sensitivity of transponder coils -  Coilcraft RF Magnetics App Note- __ Designed by Coilcraft Power Magnetics Application Note

Medium Power 125khz Oscillator -  This circuit adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz. . . Circuit by Dave Johnson P.E.-March, 2002

Medium Power 125khz Oscillator #2 -  This circuit is similar to MEDiUM POWER 125KHZ OSCiLLATOR but adds even more inverters in parallel to deliver yet more power.  The values shown are for 125KHz.. . . Circuit by David A. Johnson P.E.-March, 2002

Medium Wave 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 is supplied via RV2, a 10k potentiometer connected to the 12 Volt power supply __ Designed by David Sayles

Memory supply includes battery backu -  02/03/97 EDN Design Ideas:  The 5 to 3.3V switching regulator in Figure 1 includes battery-backup power for low-voltage memory if the 5V supply fails.  The design of such a backup circuit is difficult if only one NiCd or NiMH cell is available for the backup power source and you assume that the standby current drain on the 3.3V supply is in the 5- to 10-mA range.  Also, for the battery backup to function correctly, several actions are necessary when the switchover to backup power occurs.  One is that the whole circuit must disconnect from the 5V supply; otherwise, the battery tries to power the whole system.  Also, the switcher must shut down to a micropower condition.  The circuit in Figure 1 accomplishes all of these tasks. Design by Craig Varga, Linear Technology Corp, Milpitas, CA

Method provides fast, glitch-free isolation of I2C & SMBus signals -  24-Jun-04 EDN Design Ideas:  i2C is a popular serial protocol for power controllers, ADCs and DACs, EEPROMs, and other devices.  in certain data-acquisition and power-control situations, you must isolate the i2C master from one orslave devices for noise, grounding, or safety issues.  Also, although 128 peripherals may connect to the bus, at some point, differences in ground potential and excessive bus capacitance Design by Mark Thoren, Linear Technology Corp, Milpitas, CA

Method provides overpower protection for quasiresonant supplies -  28-Oct-04 EDN Design Ideas:  The main characteristic of quasiresonant switch-mode power supplies is that they exhibit a varying frequency when the input voltage changes.  For a flyback power supply, the power delivered to the output obeys the following equation  POUT=1/2 (LP×iP 2×FSWη], where LP is the primary inductance, iP is the peak primary current, FSW is the switching frequency, and η is the e Design by Nicolas Cyr, On Semiconductor, Toulouse, France

Micro Power Over-Temperature Alarm -  The circuit is powered for years by a single 3 volt lithium battery.  it sounds an alarm when the temperature exceeds a certain point.  With some minor changes the circuit could also be configured for an under temperature (freeze) alarm.  The circuit uses a. . . Circuit by David Johnson P.E.-June, 2000

Micropower 600kHz Step-Up DC/DC Converter Delivers 5V at 1A from a Li-ION Cell -  DN179 Design Notes __ Linear Technology/Analog Devices

Micropower Buck/Boosts Part 1: Converting Three Cells to 3.3V* -  DN109 Design Notes__ Linear Technology/Analog Devices

Micropower Buck/Boosts Part 2: Converting Four Cells to 5V* -  DN110 Design Notes __ Linear Technology/Analog Devices

Micropower DC/DC Converter with Independent Low-Battery Detector LT1304 -  DN120 Design Notes__ Linear Technology/Analog Devices

Micropower Isolated Flyback Converter with Input Voltage Range from 6V to 100V -  EDN Design Ideas:  03/30/2014     A tiny, integrated flyback converter requires minimal support components Design by LTC Design Note 509

Micropower Regulator with Comparator & Shutdown -  Switching Regulator__ Linear Technology/Analog Devices

Modded charge pump extracts power from digital signal -  EDN Design Ideas:  09/26/2015    At first glance, these charge pumps & voltage multiplier/inverters look conventional, but they have a trick up their sleeves Design by Luca Bruno & Duilio Pozzoni

Monolithic DC/DC Converters Break Speed Limits to Shrink Board Space -  DN125 Design Notes __ Linear Technology/Analog Devices

Monolithic Step-Down Regulator Withstands the Rigors of Automotive Environments & Consumes Only 100µA of Quiescent Current -  DN378 Design Notes __ Linear Technology/Analog Devices

Monolithic Synchronous Step-Down Regulators Pack 600mA Current Rating in a ThinSOT Package -  DN300 Design Notes__ Linear Technology/Analog Devices

MOSFET H Bridge -  Schematic only - no circuit desciption included __ Designed by Eugene Blanchard

MTX250 Car Amplifier: Autoformer Switch-Mode Power Supply -  This is a small 2*25 (actually, 2*50) WPC amplifier with 3-order crossover stage (configurable as LP or HP).  Of particular interest is the unconventional autoformer PS arrangement.  Since the power FET's drains are not tied to ground anymore, it needs another transformer to drive gates __ Contact klausmobile @ yahoo.Com

Multiple Output DC Converter  -  A DC converter circuit taking one single DC input and converting to parallel multiple DC outputs.   __ Designed by Andy Collison

Multiple Output DC/DC Converter Runs Off 2-Cell AA Batteries USB or AC Wall Adapter -  DN1006 Design Notes__ Linear Technology/Analog Devices

Multiple Voltage Power Supply -  Schematic only, no circuit description __ Designed by Andy Wilson

Multiplexes Automotive Sensors -  01/20/00 EDN Design Ideas:  Often, aµC limits the number of input-capture lines to accommodate the various types of automotive sensors with pulsed outputs, such as vehicle- and engine-speed sensors.  The circuit in Figure 1 uses discrete components to multiplex two sensors with open-collector outputs into a single output, thereby sharing one input-capture line of the µC.  The µC selects the sensor whose output you will measure.    Design by Adil Ansari

Negative 0.5 Volt Supply -  This simple circuit consists of two LEDs and a photo diode.  it generates a negative voltage with a current level of a couple milliamps.  it is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.  Note:  This circuit is not particularly efficient . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Negative Voltage -  A negative supply can be produced by a "Charge-Pump" circuit created with a 555, diodes and capacitors as shown in the following circuit.  The output will deliver about 50mA.  __ 555-Timer

Negative voltage generation using 555 timer  -  This circuit and project demonstrates the application of 555 to generate negative supply. The negative supply produced is about 3 volts lesser than the applied voltage due to various losses. At times the circuit requires both negative and positive supply, which is not available in the batteries. [by Ashutosh Bhatt]

Negative Voltage Generator -  takes in +12V and outputs around -11V __ Designed by pharkus @ hotmail.com

Negative-To-Negative Switch-Mode Converter Offers High Current & High Efficiency -  11/12/09  EDN Design Ideas:  Don't let variations in input voltage affect the output voltage Design by Budge Ing, Maxim Integrated Products Inc, Sunnyvale, CA

Network linearizes DC/DC converter's current-limit characteristics -  10/13/05 EDN Design Ideas:  Thermistor adds to efficiency, eliminates sense resistor Design by John Guy and Lance Yang, Maxim Integrated Products Inc, Sunnyvale, CA

New Charge Pumps offer Low Input & Output Noise -  DN243 Design Notes __ Linear Technology/Analog Devices

New High Efficiency Monolithic Synchronous Step-Down Regulator works with Single or Dual Li-ION Batteries -  DN201 Design Notes__ Linear Technology/Analog Devices

New MAR-8A & MAR-8ASM Amplifiers -  AN-60-024 Application Note__ MiniCircuits.com

New Molded-package MAV Amplifiers -  AN-60-014 Application Note__ MiniCircuits.com

New Step-Down Charge Pumps Are Tiny Efficient & Very Low Noise -  DN310 Design Notes__ Linear Technology/Analog Devices

NiCd Cells Drives Op Amp -  12/05/96 EDN Design Ideas:  Low-supply-voltage op amps, such as the LMC6582 and LMC6681 families, feature rail-to-rail i/O with a gain-bandwidth product greater than 1 MHz operating from just 1.8V.  Although impressive, this voltage is not low enough to power these amps using a single alkaline or NiCd/NiMH cell, which have typical voltages of 1.25 to 1.5V.  it is rather tempting to bridge this gap by designing a DC/DC converter Design by Alexander Belousov, Rego Park, NY

Nine-Volt Stabilized Power Supply -  Schematic only __ Designed by Tony van Roon  VA3AVR

No Design Switiching Regulator 5V Buck/Boost Positive to Negative Regulator -  DN49 Design Notes__ Linear Technology/Analog Devices

Non-Dimmable Fluorescent Ballast -  Efficient fluorescent lamps and magnetic ballasts have been the standard lighting fixture in commercial and industrial lighting for many years.  Several lamp types, rapid start, high output, and others are available for cost effective and special applications.  This user guide covers operation and development details of the non-dimmable version of our fluorescent ballast for operating a variety of lamps that are available today.   __ Designed by AT89RFD-10 / EVLB002

Notebook Power Supply Has Two Output -  03/03/94 EDN Design Ideas:  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] Design by Steven C Hageman, Calex Manufacturing Co Inc, Concord, CA

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