Dual Adjustable Power Supply Using LM 317 & LM337

admin April 12, 2011 33 Comments

Dual Adjustable Power Supply Circuit

Description

This is the circuit diagram of a dual adjustable power supply using IC’s LM 317 & LM 337.LM 317 is able to deliver a maximum of 1.5 A at a range of 1.2 V to +30V .LM 337 is the negative complement of LM317.They also have a built in short circuit protection.

Here the circuit is wired to produce a dual adjustable output of ( +15 , 0 , -15 ).The capacitors C1 to C8 provides filtering and ripple rejection.Resistors R1 & R2 controls output of LM 317.Resistors R3 & R4 controls the output of LM 337 .R1 and R4 can be turned to vary the positive and negative voltages.This circuit is a must on an electronic hobbyists workbench.

Notes

  1. The transformer should be anything that produces a min of 3 A with (24 0 24 ) output voltage.
  2. The voltage range can be further increased by increasing transformer output within the limits of IC.
  3. Do not connect a load drawing more than 2A at output.The IC,s must be fitted with heat sinks for better protection.

Parts List

C1, C2 2200 uF 50V Electrolytic Capacitor
C3, C4, C5, C7 2.2 uF 50V Electrolytic Capacitor
C6, C8 100 uF 50V Electrolytic Capacitor
R1, R4 5K Potentiometer
R2, R3 220 Ohms 1/4 W Resistor
D1 to D4 IN 4007 Diodes
U1 LM317 U2 LM337 T1 24 0 24 Center Tapped 2 Ampere Transformer
S1 SPST 2 Ampere Switch
Extra Heat sinks for two IC’s , Power Cord, Casing, Wire etc

Dual Adjustable Power Supply Circuit Diagram.

Dual power supply circuit

Dual power supply circuit

 

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Comments
  • pragati
    February 1, 2015

    can i get the design details of this circuit?

    Reply
  • George Nabil
    December 26, 2014

    YOU ARE AWESOME GUYS
    I’LL MAKE THIS CIRCUIT SOON
    AND THERE IS A LOT OF QUESTION ABOUT CIRCUIT I WANT TO TALK ABOUT IT CAN I ASK YOU SIR ??

    Reply
  • Usman Idrees
    November 14, 2013

    Are there any formulas to calculate resistor and capacitor values? if yes, then what are they?

    Reply
  • huzaifa
    November 11, 2013

    what should we do with open ends of the variable resistors R1 AND R4??….reply fast

    Reply
    • pragati
      February 1, 2015

      they are simply 5k potentiometers. one of the ends are connected to c1 c4 junction and the other ends are given as input to pin no 1 of 317 and 337.hope it helps.

      Reply
    • pragati
      February 1, 2015

      can i get the PCB design for this ckt

      Reply
    • pragati
      February 1, 2015

      can any one give me the PCB design for this ckt. it would be a great help..

      Reply
  • Saraii Maute
    October 19, 2013

    If I use center-tapped 12V 750mA transformer, what else in the circuit should I replace so it would work just fine? Please help me. thanks in advance..:)

    Reply
  • Xhurda
    September 25, 2013

    Hi! Where does the other side of R1 and R4 connect?

    Reply
  • Achira
    July 11, 2013

    hi
    why we use c1 12 parallel? cant use only one 2200uf? also in other side only 100uf one only?
    reply soon……

    Reply
    • Seetharaman
      July 12, 2013

      Hi C1 is for smoothing + voltage bus(depends on the current load on the bus) and similarly C2 is for smoothing – voltage bus.

      Reply
      • Achira
        July 13, 2013

        thank you
        but i want to know is why use c3 and c4 parallel with c1 and c2.

        Reply
        • Seetharaman
          July 14, 2013

          THe electrolytic capacitors are wound capacitors their equivalent circuit will indicate it contains and inductive component also in series. This makes the capacitor ineffective in decoupling high frequency component in the power supply. to achieve this a low value disc like 0.1 or 0.22 uF or 2.2uF tantalum capacitor used in parallel with high value electrolytic capacitors. you may go through the following link for better understanding
          http://www.intersil.com/content/dam/Intersil/documents/an13/an1325.pdf

          Reply
  • Gary
    May 2, 2013

    Hi can I ask if this would be suitable, I need a supply with +20v DC and -20v DC it is for an audio pre-amplifier, would I still need to use a 24-0-24v transformer or could I use one with lower voltage and also would the transformer need to be such high current?
    Thanks
    Gary

    Reply
    • Seetharaman
      July 14, 2013

      Hi Gary The audio pre-amps are class A type. They always draw the same current whatever may be the input signal level. for a +20 and -20 volts use a transformer of 15-0-15 volts transformer with rectifiers and decoupling capacitors will give the required voltage. no regulation is required.

      Reply
  • Eujean
    April 3, 2013

    Hi there!! Was wondering about the caps. Are they meant to not have a junction on the ground? Having trouble getting the lm337 to work..

    Regards
    Eujean

    Reply
    • Seetharaman
      April 4, 2013

      Hi Eujean the junctions of C1, C2; C3, C4; C5, C6; C7, C8 to be connected to common GND. The dots are missing. The circuit is correct and will work.

      Reply
  • dual rail supply and ground
    March 14, 2013

    […] oscillators and ICs like the 555, logic gates, etc.). Something similar to what you see here: http://www.circuitstoday.com/dual-ad…g-lm-317-lm337 My question is about grounding the various parts of the circuit. The common on the components just […]

    Reply
    • Seetharaman
      March 16, 2013

      Hi Normally zero volt reference bus should be connected to ground, where the requirement is both positive and negative voltage like op-amp IC audio amplifiers etc .

      Reply
  • mohamed
    March 2, 2013

    hi every one
    there’s something abt that circuit i have used all the components but the output is abt 27.7 -27.7 v insteade of 15 -15
    and i doesn’t starts at 0 v , it starts at 1.6 v

    Reply
  • faraz shahid
    August 14, 2012

    how to make the display of power supply digital

    Reply
    • Seetharaman
      March 16, 2013

      Hi Shahid you can use standard 200mV 3 1/2 or 4 1/2 panel meter modules with its own separate power supply 5 or 9 volt and suitable multiplier and shunt resistance to convert the input to the required 200mV range.

      Reply
  • rahul
    May 29, 2012

    sir
    is there a way to buit dual power supply using only lm 317??

    Reply
  • rahul
    May 27, 2012

    sir
    can we built dual power supply using only lm 317 ???

    regards
    rahul

    Reply
  • Seetharaman
    May 27, 2012

    HiRahul With LM317 & 337 YOU CAN USE A SINGLE CENTER TAPPED TRANSFORMER. IF YOU WANT TO USE 2 lm317 YOU REQUIRE A TRANSFORMER with 2 independabt secondaries and 2 rectifier and filter circuits to takecare. it will become 2 independant supplies in sereies.

    Reply
  • rahul
    May 26, 2012

    hi every one has any one assembled this circuit ?? anyway can any one tell me instead of using lm337 can two lm317 be used…???

    Reply
  • Shaun Duffus
    May 8, 2012

    are the heat sinks completely necessary or will it work fine without them?

    Reply
  • Hamid
    December 23, 2011

    Thanks alot i have got more help

    Reply
  • kambo
    January 29, 2011

    good work God bless you

    Reply
  • sniper2g8
    September 29, 2009

    The R1&R4 where is it going to conect…..
    is it short circuit or what

    Reply
    • pragati
      February 1, 2015

      they are simply 5k potentiometers. one of the ends are connected to c1 c4 junction and the other ends are given as input to pin no 1 of 317 and 337.hope it helps.

      Reply

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