Dual Polarity Power Supply
Electronic Schematics > Power > Dual Polarity Power Supply

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.


This is the schematic of the Dual Polarity Power Supply


Part Total Qty. Description Substitutions
C1, C2 2 2200uF 35V Electrolytic Capacitor  
C3, C4, C5, C7 4 1uF 35V Electrolytic Capacitor  
C6, C8 2 100uF 35V Electrolytic Capacitor  
R1, R4 2 5K Pot  
R2, R3 2 240 Ohm 1/4 W Resistor  
BR1 1 2A 30V Bridge Rectifier  
U1 1 LM317 Adjustable Positive Regulator  
U2 1 LM337 Adjustable Negative Regulator  
T1 1 30V Center Tapped 2 Amp Transformer  
S1 1 SPST 2 Amp Switch  
MISC 1 Heatsinks For U1 And U2, Line Cord, Case, Knobs For Pots, Wire  


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).

Also check this LM317 Calculator

Title: Dual Polarity Power Supply
electronic circuit
Source: www.aaroncake.net
Published on: 2005-02-03
Reads: 961
Print version: Print version

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