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

Last Updated: October 18, 2017 05:04 AM

Circuits Designed by Dave Johnson, P.E. :

 

0VAC to 280VAC Variable Isolated AC Voltage - I designed and built this circuit about 25 years ago.  It came in handy for many projects that were powered from 120 VAC, 240 VAC and 277 VAC.  It provides complete isolation from the power line.  It uses two 1:1 isolation transformers that are wired in parallel . . . Hobby Circuit designed by David Johnson P.E.-July, 2000

12v-24v AC & DC Day/Night Switch - The circuit uses a bridge rectifier circuit to convert AC into DC.  A 12v zener diode limits the operating voltage of the circuit to 12v.  A tiny Schmitt trigger inverter and a phototransistor detects the ambient light intensity.  If there is sufficient light, the inverter disables a push-pull oscillator circuit . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2012

240VAC to 5VDC Power Supply - This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines. . . Circuit by David Johnson P.E.-February, 2002

9v Battery Eliminator - 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 circuit. . . Circuit by David Johnson P.E.-December, 2009

AC to DC (240v to 5v)Power Supply - This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
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0-14V variable power supply with current limiting, Version 2-  For the experimenter and homebrewer, a variable power supply with current limiting can be very handy.  There are not too many of these commercially available and those which are, are fairly expensive.  However, it does not cost much to build your own.  Version 2 of the variable power supply fixes a problem with the original design which was designed a number of years ago.  The problem is the current sense resistor is outside the voltage regulation feedback loop, which causes the output voltage to vary a little with current.  The voltage drop is only 200 mv for a 2A current and that generally isn't a problem, but it would be nice if that drop was not there.  This new circuit puts the current sense resistors on the supply side, rather then the ground return, so that the current sense resistors are inside the voltage regulation loop. __ Designed by Steven "Melt Solder" Weber  KD1JV

0-50v Variable Power Supply using LM317-  Presented here is a 0-50V, 1A variable power supply that has been designed using positive-adjustable voltage regulator LM317 IC.  This IC normally generates voltages in the range of 1.2V to 25V,...__ Electronics Projects for You

0v To 50 Volt Variable Regulator-  A very simple variable power supply circuit can be made using this electronic circuit diagram . This variable regulator circuit will provide an variable regulated output voltage , between 0 and 50 volts .  The CA3140 operational amplifier compares the regulator output to a reference voltage , that depends on the R9 value.0V to 50__

0VAC to 280VAC Variable Isolated AC Voltage-  I designed and built this circuit about 25 years ago.  It came in handy for many projects that were powered from 120 VAC, 240 VAC and 277 VAC.  It provides complete isolation from the power line.  It uses two 1:1 isolation transformers that are wired in parallel . . . Hobby Circuit designed by David Johnson P.E.-July, 2000

12V Distribution in μTCA Redundant Power Subsystem-  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

12v-24v AC & DC Day/Night Switch-  The circuit uses a bridge rectifier circuit to convert AC into DC.  A 12v zener diode limits the operating voltage of the circuit to 12v.  A tiny Schmitt trigger inverter and a phototransistor detects the ambient light intensity.  If there is sufficient light, the inverter disables a push-pull oscillator circuit . . . Hobby Circuit designed by David A. Johnson P.E.-March, 2012

1A Variable Regulated Power Supply-  A 'must-have' for the experimenter. __ Designed by Peter Parker VK3YE

200W AdvancedTCA Hot Swap Controller-  The LTC4252 negative voltage Hot Swap controller allows a board to be safely inserted and removed from a live backplane.  Output current is controlled by three stages of current limiting: a timed circuit breaker, active current limiting and a fast feedforward path that limits peak current under worst-case catastrophic fault __ Linear Technology/Analog Devices App Note, Mar 26th 2010

231 Volt Dimmer-  Find out how to put together a simple but efficient PWM dimmer circuit for LEDs. __ Designed by REUK-Renewable Energy UK website

240VAC to 5VDC Power Supply-  This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines. . . Circuit by David Johnson P.E.-February, 2002

2-Wire Virtual Remote Sensing for Voltage Regulators-  Linear Technology AN126 __ Designed by Jim Williams - Oct 1st, 2010

3-30 V/2.5 a Stabilized power supply-  This is a very useful project for anyone working in electronics.  It is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics work shop.  It covers a wide range of voltages being continuously variable from 30 V down to 3 V. __ Contact IQ Technologies

3-Phase Rectifier & Voltage Reducer form a Offline Single-Phase Supplies-  EDN-Design Ideas -- 04/06/12  Missing diodes create gaps to allow voltage reduction. __ Circuit Design by JB Castro-Miguens, Cesinel, Madrid, Spain; C Castro-Miguens, University of Vigo, Spain; M Pérez Suárez, University of Vigo, Spain; and A Abal Pena, Tekplus, Vigo, Spain

3V supply Delivers 12V p-p to piezo speaker-  10/16/03  EDN Design Ideas:  Low-profile piezoelectric speakers can provide quality sound for portable electronic devices, but they require voltage swings greater than 8V p-p across the speaker element.  Yet, most portable devices include only a low-voltage pow __ Circuit Design by Royce Higashi and Tony Doy, Maxim Integrated Products, Sunnyvale, CA

5 V Regulator Supplies High Transient Current for Dynamic Power Controlled DAC -  Follow the instructions contained in the Readme file for installing and using the evaluation software.  , Functional Block Diagram Figure 8 shows the test setup block diagram, and the EVAL-CN0198-SDPZ-SCH-RevX.  pdf file has the circuit schematics.  Connect the USB cable from the PC to the mini-USB connector on the SDP board and launch the evaluation software.  Information and details regarding test setup and how to use the evaluation software for data capture can be found in the CN-0198 User Guide__ Analog Devices from the Lab

5V power supply teams low-dropout regulator, charge pump-  8-Jan-04 EDN Design Ideas:  Auxiliary power of 3.3V is replacing the 5V auxiliary power that "silver boxes" supply in most computer systems, but some circuits still require a 5V supply.  Such systems impose the messy task of creating a central 5V auxiliary supply from the 3.3V auxiliary supply and then routing 5V power throughout the motherboard __ Circuit Design by Jim Christensen, Maxim Integrated Products, Sunnyvale, CA

5V powersupply-  This circuit will regulate voltage to 5V input range is 6V.12V.  The diode prevents the circuit being damaged when the input is connected the wrong way around.  The resistor and LED are optionial, they are for power on indication__

9v Battery Eliminator-  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 circuit. . . Circuit by David Johnson P.E.-December, 2009

A Variable Power Supply for the FM Transmitters-  This is a fairly simple, yet very versatile workbench power supply.  With a current limit of 1.5 amperes and a variable voltage from 2.7 volts to 16.5 volts on the output of the LM317T, this unit will come in very handy for your diversified electronic projects ( which usually include different DC voltages.  I have used it mainly for supplying my FM transmitters with different voltages, to see the different effects it has on the units.  In fact, I use it for all my FM transmitters.  It has served me well.  and is still serving proudly! __ Designed by braincambre500 @ yahoo.com

A Variable power supply with adjustable current limiting-  A Variable power supply with adjustable current limiting - new design! 0-14V output up to 5A current. __ Designed by Steven Weber, KD1JV

AC to DC (240v to 5v)Power Supply-  This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines . . . Hobby Circuit designed by David A. Johnson P.E.-February, 2002

Add foldback-current protection-  07/21/05  EDN Design Ideas:  Enhance three-terminal regulator with foldback oversight __ Circuit Design by Rafael García-Gil and JM Espí, Electronic Engineering Department, University of Valencia, Spain

Add gain to an absolute-value Amplifier-  08/22/02 EDN Design Ideas:  The absolute-value amplifier is a basic building block in test-and-measurement and signal-processing applications.  The addition of a DPP (digitally programmable potentiometer] adds another dimension, G (gain], to this key circuit.  Because the gain is programmable, you can use the circuit as an absolute-value amplifier (G&1] or an absolute-value attenuator (G>1] __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CA

Adjustable Low-voltage Power Supply-  If you want to check the behaviour of an electronic circuit at low voltages, an adjustable power supply as shown here may be heLPFul.  Powered from a 3 to 16 volts source ( DC for sure) , it will provide a stable output voltage in the 0 to 1.5 V rangemust register on this site __ Designed by Published in Elecktor July/Aug, 2010

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

Adjustable power supply using LM317-  voltage regulator for1.2V to35-Volt output voltages and up to1A load __ Designed by Tomi Engdahl

Adjustable Power Supply with Charger-  This power supply has adjustable and charger output.  The charger circuit can be use for cellular phone.  The adjustable output serves as multipurpose power supply.  It can handle a 1 ampere current.  The 317 must have a heat sink. __ Designed by Milardo de Guzman

Adjustable Step Up Voltage Regulator-  Find out more about a step up voltage regulator used to output a voltage higher than the input voltage. __ Designed by REUK-Renewable Energy UK website

Adjustable Voltage Motor Controller-  One of the nice things about flying electric is you can test run your motor in the house, workshop, or in the yard and the neighbors won't complain.  The problem is how to control the speed of the motor.  One way is to use the plane, radio, and speed control with the motor in it.  That's no fun! __ Designed by One of the nice things about flying electric is you can test run your motor in the house, workshop, or in the yard and the neighbors won't complain. The problem is how to control the speed of the motor. One way is to use the plane, radio, and speed control with the motor in it. That's no fun! Mount the motor on the bench and just plug the battery into the motor. That's even worse! It's hard on the motor and gearbox.

AdvancedTCA Four Fuse Monitoring Application-  The LTC4261 negative voltage Hot Swap controllers allow a board to be safely inserted and removed from a live backplane.  Using an external N-channel pass transistor, the board supply voltage can be ramped at an adjustable rate.  The devices feature independently adjustable inrush current and overcurrent limits to minimize stresses __ Linear Technology/Analog Devices App Note, Mar 26th 2010

AdvancedTCA with High-Side & Low-Side Ideal Diode-OR & Hot Swap Controller with I2C Current & Voltage Monitor-  The LTC4355 is a positive voltage ideal diode-OR controller that drives two external N-channel MOSFETs.  Forming the diode-OR with N-channel MOSFETs instead of Schottky diodes reduces power consumption, heat dissipation and PC board area. __ Linear Technology/Analog Devices App Note, Mar 26th 2010

AMC 2V & 3.3V Hot Swap Controller Application with Digital Monitoring-  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

AN126 - 2-Wire Virtual Remote Sensing for Voltage Regulators - Clairvoyance Marries Remote Sensing-  Linear Technology AN126 __ Designed by Jim Williams - Oct 1st, 2010


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

 


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