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Variable Power Supplies
Power Supplies -- Main Page
Variable Power Supplies:   #'s - A       B - L         M - Z


Last Updated: November 21, 2017 05:46 AM

Circuits Designed by Dave Johnson, P.E. :

Battery Eliminator - If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be. . . Circuit by David A. Johnson P.E.-June, 2005

Capaciatance-Based Touch Switch - This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Circuit Eliminates 9v Battery - If you use 9v battery powered devices for long periods of time, you may get tired of constantly changing batteries.  The circuit below can be wired into any 9v battery powered device, drawing power from an external AC to DC power adapter.  I designed the c . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2009

LM317 adjustable voltage regulator used in Battery Eliminator Circuit - If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2005


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

Basic Power Supply-  well filtered variable1.2-30 volts at5 amps using LM338K __ Designed by Aaron Cake

Battery Eliminator-  If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be. . . Circuit by David A. Johnson P.E.-June, 2005

Capaciatance-Based Touch Switch-  This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Cascoded stack yields multiple voltages-  03/16/00 EDN Design Ideas:  Although the cascode voltage-reference configuration in Figure 1 may seem obvious, the choice of R 1 and the bypass capacitors is critical.  At first glance, stacking up references of the same voltage to produce a collection of voltages seems straightforward.  However, nothing comes without precautions and an understanding of limitations. __ Circuit Design by Clayton Grantham

Circuit adds foldback-current protection-  21-Jul-05 EDN Design Ideas:  Enhance three-terminal regulator with foldback oversight __ Circuit Design by Rafael Garca-Gil and JM Esp, Electronic Engineering Department, University of Valencia, Spain

Circuit Eliminates 9v Battery-  If you use 9v battery powered devices for long periods of time, you may get tired of constantly changing batteries.  The circuit below can be wired into any 9v battery powered device, drawing power from an external AC to DC power adapter.  I designed the c . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2009

Circuit Secures Bootstrap Operation Under Light Load-  05/12/11  EDN Design Ideas:  Additional circuit lets a capacitor charge, preventing voltage dips.  A previous Design Idea highlights a potential issue of a bootstrap IC under light-load or prechargedload operation (Reference 1).  The circuit in Figure 1, with the additional circuit in the green box, fixes the problem of a voltage dip in the bus-voltage signal.  The waveforms in Figure 2 demonstrate how this problem takes place in buck converter IC1B when its output voltage, VBUS, dips below the regulation point at a fixed rate under no load.  By inspecting the other traces in Figure 2, you can conclude that the dip of VBUS occurs __ Circuit Design by Chee Hua How

Clairvoyance Marries Remote Sensing-  Linear Technology AN126 __ Designed by Jim Williams - Oct 1st, 2010

Compact μTCA 12V & 3.3V Hot Swap Solution for Advanced Mezzanine Cards-  The LTC4223 positive voltage Hot Swap controller allows a board to be safely inserted and removed from a live AMC or MicroTCA backplane.  It controls the main 12V supply with an external N-channel MOSFET and the 3.3 V auxiliary supply with an integrated switch.  The 12V output ramp rate is adjustable and includes inrush current __ Linear Technology/Analog Devices App Note, Mar 26th 2010

Constant Current Battery Charger-  A simple method of charging a battery from a higher voltage battery is shown in the circuit below to the left.  Only one resistor is needed to set the desired charging current and is calculated by dividing the difference in battery voltages by the charge current.  So, for example if 4 high capacity (4000 mA hour) ni-cads are to be charged at 300 mA from a 12 volt battery, the resistor need, __ Designed by Bill Bowden

Discreet LDO Voltage Regulator-  Do you need a simple LDO voltage regulator, but an IC version that meets your needs is not available?Make your own using this circuit.  The circuit in the drawing is the actual circuit that I built and used successfully to power a shortwave radio which __ Designed by Andrew R. Morris

Dual +/-25V LAB Supply-  Up to 800mA ( typical) output current at +/-25V. __ Designed by Rod Elliott  ESP

Dual 12V & 3.3V Hot Swap Application for Two Advanced Mezzanine Cards-  The LTC4242 Hot Swap controller allows safe board insertion and removal for two independent slots on a PCI Express backplane.  External N-channel transistors control the 12V and 3.3 V supplies while integrated switches control the 3.3 V auxiliary supplies.  Both 12V and 3.3 V supplies can be ramped up at an adjustable rate.  Dual __ Linear Technology/Analog Devices App Note, Mar 26th 2010

Dual power supply Delivers 8A with no heat sinks-  03/30/00 EDN Design Ideas:  The circuit in Figure 1 is a high-current dual supply that provide as 5 and 3.3V at currents as high as 8A.  The circuit uses a fixed-frequency, two-output, current-mode synchronous-buck- controllerPFD contains several circuits, scroll to find this one __ Circuit Design by John Seago, Linear Technology Corp, Milpitas, CA

Dual PSU-  I reckon that every electronics hobbyist should build at least one general-purpose bench PSU.  Apart from being an invaluable piece of kit, the project will cover a reasonably wide range of topics, making it a very worthwhile learning exercise. __ Designed by Mark Hennessy

Dual Regulated Power Supply-PSU-  In this circuit, the 7815 regulatates the positive supply, and the 7915 regulates the negative supply.  The transformer should have a primary rating of 240/220 volts for europe, or 120 volts for North America.  The centre tapped secondary coil should be rated about 18 volts at 1 amp or higher, allowing for losses in the regulator.  An application for this type of circuit would be for a small regulated bench power supply __ Designed by Andy Collison

Dual-voltage regulator meets USB-power needs-  19-Aug-04 EDN Design Ideas:  This design idea stems from the limited availability of IC voltage regulators that can meet key USB-power specs, coupled with the need for turn-on sequencing and rise-time control at each output.  As always, for PC-related designs, minimum cost is a primary motivation.  USB specs require all loads to limit inrush current to less than 100 mA plus 50 C of charge when powered on __ Circuit Design by Wayne Rewinkel, National Semiconductor, Phoenix, AZ

Easy Power Supply-  I have done some work with DC PSUs over the past few months but some of the designs were either complex or "basic performers".  I therefore decided that it was about right to produce a bench PSU that was simple enough to be made into another kit and have a reasonable performance too. __ Designed by Harry Lythall-SM0VPO

Flasher/Dimmer Lantern-  The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design.  For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work.  The flasher mode __ Designed by Tony van Roon  VA3AVR

GainClone Monoblocks-  Impressed with the LM3875, I decided to build four mono-block amps.  I never got around to building them in the end, but maybe the write-up of my experiments might be useful. __ Designed by Mark Hennessy

High Current Power Supply-  Since my page was first posted, I have received a number of emails asking about a high current power supply.  I looked around, but couldn't find one that was suitable.  So, I designed this.  It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents __ Designed by Aaron Cake

High Current Power Supply-  Since my page was first posted, I have received a number of emails asking about a high current power supply.  I looked around, but couldn't find one that was suitable.  So, I designed this.  It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents. __ Designed by Aaron Cake

High Current Regulated Power Supply-  The high current regulator below uses an additional winding or a separate transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency.  For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should be close to the output voltage.  The LM317 requires a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the ( 0.1ohm) equalizing resistors ( 1volt at 10 amps) , so a separate transformer and rectifier/filter circuit is used that is a few volts higher than the output voltage __ Designed by Bill Bowden

High Current Regulated Supply-  Current of LM317 voltage is increased by using an additional power transistors. __

High-Current Battery Discharger-  If you have a motley collection of 12V batteries in varying states of health, this simple circuit will allow you to easily check their capacity.  Its basically a high-current discharge load which is controlled by the NiCd Discharger.  This involved increasing the existing 10F capacitor across LED1 to 100F, to enable it to supply the__

High-current supply uses standard three-terminal regulator-  07/22/04 EDN Design Ideas:  Voltage-regulator design for high output currents can be a critical and difficult task.  Although voltage regulators with 1A maximum output current are simple to design, thanks to 78xx three-terminal voltage regulators, at output currents higher than 1A output, problems arise.  For high output currents, voltage regulators usually use parallel-connected power transistors __ Circuit Design by I Hakki Cavdar, Karadeniz Technical University, Trabzon, Turkey

Lantern Flasher/Dimmer-  Basically a high-efficiency dimmer, but can also be used as a flasher.  In dimmer mode, the LM358 (dual op-amp) is wired to send pulses at a constant frequency.  By adjusting the width of these pulses, brightness of the bulb is controlled.  In flasher mode, the same potentiometer is used to control the frequency, from about 1 to 20 flashes per second__ copy of geocities.com/tomzi.geo page

Lantern Flasher/Dimmer-  The electronic lantern control circuit ( fig.1) adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design.  For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work.  The flasher mode is useful for warning other drivers __ Contact:  Charles Wenzel of Wenzel Associates, Inc.

Lantern Flasher/Dimmer-  The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design.  For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work.  The flasher mode __ Designed by Tony van Roon  VA3AVR

LM317 adjustable voltage regulator used in Battery Eliminator Circuit-  If you use a 1.5v or a 3v battery powered MP3 player for long periods of time, you may get tired of constantly changing batteries.  Some older players do not work will NiMH
rechargeable batteries so changing out batteries can get expensive.  The circuit be . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2005

LM317 Regulator with Pass Transistor-  The LM317T output current can be increased by using an additional power transistor to share a portion of the total current.  The amount of current sharing is established with a resistor placed in series with the 317 input and a resistor placed in series with the emitter of the pass transistor.  In the figure below, the pass transistor will start conducting when the LM317 current reaches about 1 amp, due to the voltage drop across the 0.7 ohm resistor __ Designed by Bill Bowden

LM317 variable power supply-  It's a variable power supply based on a lm317 voltage regulator the range of power is between 1.6 and 13.5 volt, you can get till 1, 5 Amp.  if supply the IC of a good cooler such as an aluminium plate.  The range can be varied by turning the 1k linear potentiometer.  This circuit is good for that kind of little home appliances like walkman, disc player, gsmcharger. __ Designed by Alfred73

LM317 variable Power Supply-  A truly timeless circuit.  LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink.  It's ideal for just about any application. __ copy of geocities.com/tomzi.geo page

LM317 Variable Voltage Regulator-  The LM317T is a adjustable 3 terminal positive voltage regulator capable of supplying in excess of 1.5 amps over an output range of 1.25 to 37 volts.  The device also has built in current limiting and thermal shutdown which makes it essentially blow-out proof __ Designed by Bill Bowden

Low Voltage High Current Time Delay-  In this circuit a LM339 quad voltage comparator is used to generate a time delay and control a high current output at low voltage.  Approximatey 5 amps of current can be obtained using a couple fresh alkaline D batteries.  Three of the comparators are wired in parallel to drive a medium power PNP transistor ( 2N2905 or similar) which in turn drives a high current NPN transistor ( TIP35 or similar).  The 4th comparator is used to generate a time delay after the normally closed switch is opened __ Designed by Bill Bowden

Low-Voltage Adjustable Regulator-  Need to operate a CD, DVD or MP3 player from the cigarette lighter socket in your car? Or perhaps run a digital still or video camera or some powered speakers from the power supply inside your PC? This Low-Voltage Adjustable Regulator will step the voltage down to what's needed.  It has jumper shunts to select one of six common output voltages ( from 3-15V) and depending on the input voltage and the heatsink ( s) you use, it can deliver an output current of just over 4A.__ SiliconChip

LTC4222 μTCA Application Supplying 12V Payload Power to Two μTCA Slots-  The LTC4222 Hot Swap controller allows two power paths to be safely inserted and removed from a live backplane.  Using external N-channel pass transistors, board supply voltages and inrush currents are ramped up at an adjustable rate.  An I2C interface and onboard ADC allows for monitoring of current, voltage and fault status __ Linear Technology/Analog Devices App Note, Mar 26th 2010

LTC4225 μTCA Application Supplying 12V Power to Two μTCA Slots-  The LTC4225 offers ideal diode and Hot Swap functions for two power rails by controlling external series connected N-channel MOSFETs.  MOSFETs acting as ideal diodes replace two high power Schottky diodes and the associated heat sinks, saving power and board area.  Hot Swap control MOSFETs allow boards to be safely inserted __ Linear Technology/Analog Devices App Note, Apr 22, 2011

LTC4360/LTC4361/LTC4362 Overvoltage / Overcurrent Protection Controllers-Video Product Brief-  The LTC4360/LTC4361/LTC4362 overvoltage/overcurrent protection controllers safeguard 2.5V to 5.5V systems from input supply overvoltages and overcurrents.  They are designed for portable devices with multiple power supply options including wall adapters, car battery adapters and USB ports.  The LTC4360 controls an external __ Linear Technology/Analog Devices App Note, Alison Steer-Product Marketing Manager Aug 25th 2010


Variable Power Supplies:   #'s - A       B - L         M - Z


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Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


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