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, 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

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

anonymous
Dual Polarity Power Supply
Tuesday, September 09, 2008 12:45:11 PM
I only need d schematic diagram of the +15v and -15v dual power supply and the components
Simon
Dual Polarity Power Supply
Sunday, July 06, 2008 10:56:25 PM
Hi, I like the dual supply circuit, and would like to know if Transformer T1 has no centre tap, with the rest of the circuit remain the same, is the GND still applicable? Singapore.
Allen Walker
Dual output DC Power supply(output=+15v and -15v) with less than 15 components
Monday, June 16, 2008 1:21:38 AM
Hi, Can i have the schematic diagram of a dual output DC power supply of output +15 volts and -15 volts and the schematic diagram with not more than 15 components in it. Help me to identify the sub-sections[explanation of each and every component] that make up the power supply and an explanation on the operation of the power supply. Thank you. Please reply ASAP.
JL
Dual Polarity Power Supply
Monday, June 09, 2008 2:49:37 AM
Hihi.. Ur notes say that U1 and U2 can only go down to a min of+/-1.2V if add two 1N4003 diodes in series. Than how to make a power supply with a voltage output range from +15V and -15V?
maria
Dual Polarity Power Supply
Wednesday, June 04, 2008 6:30:15 AM
i am not getting any idea about how to connect the U1 and U2 ics, because the pins are labelled as Vin, Vout and adj in the data sheet, but here the pins are labelled as 1,2,3. can anyone guide me???

(Editor's notes: U1: 3 = In, 1 = Adjust, 2 = Out U2: 2 = In, 1 = Adjust, 3 = Out)

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
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