Dual Polarity Power Supply


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This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage.

Schematic

This is the schematic of the Dual Polarity Power Supply

Parts

Part
Total Qty.
Description
Substitutions
C1, C222200uF 35V Electrolytic Capacitor
C3, C4, C5, C741uF 35V Electrolytic Capacitor
C6, C82100uF 35V Electrolytic Capacitor
R1, R425K Pot
R2, R32240 Ohm 1/4 W Resistor
BR112A 30V Bridge Rectifier
U11LM317 Adjustable Positive Regulator
U21LM337 Adjustable Negative Regulator
T1130V Center Tapped 2 Amp Transformer
S11SPST 2 Amp Switch
MISC1Heatsinks For U1 And U2, Line Cord, Case, Knobs For Pots, Wire

Notes

  1. Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
  2. U1 and U2 get quite hot and will require heatsinks. A fan is usually not needed.
  3. You can, of course, add a volt and amp meter.
  4. U1 and U2 can only go down to a minimum of +-1.2V. If you need to go lower, you can add two 1N4003 diodes in series with the output of the regulator. The diodes drop about 0.6V each, which will allow the supply to go to 0. Note that this will also decrease your maximum output voltage by 1.2V. (Thanks to Steve Horvath for the suggestion).

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Comments

hammad chohan
Dual Polarity Power Supply
Tuesday, April 29, 2008 2:16:21 AM
its good but put some alternative component then it can be a very good project 4 the begar
Fuzail (PAF-KIET)
Dual Polarity Power Supply with max 5 amps
Thursday, April 24, 2008 3:28:51 AM
any one around who can send me circuit diagram of dual polarity variable power supply having 5 amp max current
Kirk
Dual Polarity Power Supply
Sunday, April 06, 2008 6:48:02 AM
Genius wanted. Anyone got a design for a +/- 48v regulated power supply. I have an Infinity Sub Woofer that suffers from hum. I have determined that the power rails are not smooth and even with extra capacitive smoothing it is not good enough. I wish to ensure that the power supply is as smoth as it can be. Many thanks to anyone who can help. Kirk.
anonymous
Dual Polarity Power Supply
Friday, March 07, 2008 10:48:10 AM
A fuse would be rather a good idea, as would an earthed chassis and dual pole dual throw switch to
Aran Sander
Dual Polarity Power Supply
Thursday, February 21, 2008 11:04:00 PM
how do you compute for the value of each parts for this design? can you give me the computation and the process how do you design and the operation of the design. you can email me @ aran_sander_14@yahoo.com , hoping for your reply thanks a lot
EDWIN
Dual Polarity Power Supply
Tuesday, February 19, 2008 8:05:40 AM
Hi, just wanted to know if you did experience any problems with the outputs, meaning did you ever come across different output voltages between the +ve amd -ve outputs? i need a reply ASAP thank you
josh
variable power supply with 3 -5A and cheaper
Tuesday, February 19, 2008 3:57:10 AM
do you have a design of power supply virable and can accept up to 5A and cheaper and in minimum size
Matt
Dual Polarity Power Supply
Tuesday, January 29, 2008 6:33:51 PM
I have to build a power supply for a class project and i have never built one before. what do you think would be the best way to go
Aska
Dual Polarity Power Supply
Thursday, January 24, 2008 4:14:48 AM
does work this circuit work in a 220 outlet and can produce a negative and positive 15 volts output
edwin
Dual Polarity Power Supply
Tuesday, January 22, 2008 5:31:33 PM
i have chosen this circuit as my project in my college course but i just want to know if you have actually tested this circuit and got the results you expected?
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