Power Supply Circuit using LM 317

admin December 8, 2011 11 Comments

Power Supply Circuit-40 Volts-2A

Description.

This is a power supply circuit diagram of 40Volts, that is able to deliver 2A current.This circuit is suitable for power amplifiers .Transistor TIP 42 A is used as a pass transistor to increase the current capabilities.Voltage regulator LM 317 is the heart of this circuit .Here the out put voltage is set to 40 V by R5 & R8.If you want any other out put voltage use a 10 K pot instead of R5 and adjust it.

Parts List.

R1_______________3R9 1 or 2W Resistor
R2______________   22R  1/4W Resistor
R3_______________6K8 1/4W Resistor
R4_____________     220R  1/4W Resistor
R5_______________4K7 1/2W Resistor

C1____________        3300µF  50V Electrolytic Capacitor (or 4700µF 50V)
C2,C5__________       100nF  63V Polyester Capacitors
C3______________   10µF  63V Electrolytic Capacitor
C4_____________      220µF  50V Electrolytic Capacitor

D1_____                         Diode bridge  4A
D2___________          1N4002  Diode
D3______________  LED  Any  color
U1___________          LM317
Q1____________       TIP42A  Transistor
T1_____________     230V Primary, 40V  2A ,Secondary,
Mains transformer.
Note.

If diode bridge is not available make one using four 1N 4007 Diodes.

Power Supply Circuit Diagram.


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Comments
  • G3TSA
    August 13, 2014

    The LM317 is specified “Maximum input voltage 40 volts”

    The 50 volt ac input will produce 75 volts input when no load, not clever.

  • seetharaman
    October 29, 2011

    Hi Leon TIP42 can handle a maximum of 4amps hence you may have to use 10nos in parallel

  • Leon Remp
    October 29, 2011

    Hi Sir i am working on a project that requires 36 volts and 30 to 35 amp. Can the tip43 be used in parrallel the same as 2n2955 to boostcurrent output. I have Tip42 on hand.

    Thanks in advanance Leon

  • Seetharaman
    May 27, 2011

    hi frank go through the following data sheet.
    http://www.national.com/ds/LM/LM117.pdf

  • Frank
    May 26, 2011

    Thanks you very much.

    May I know why we need D2 to protect LM317 against C3?

    Why do we need both C1 and C2 and not just use 1 capacitor instead? (same for C4 and C5)

  • Frank
    April 6, 2011

    Hi, may I know how the transistor Q1 affects the circuit? And what is the diode D2 for?

    Thanks.

    Frank

    • admin
      April 8, 2011

      Q1 is a pass transistor which conducts the extra current. LM317 can handle only 1A. Diode D2 is a protection diode. Protection diodes are required for LM317 for output voltages above 25V and capacitance values above 10uF. Here D2 protects LM317 against C3.

  • Edgardo Diolola
    July 24, 2010

    Dear Seetharaman,
    Thank you very much for the information,
    More power to you.

  • seetharaman
    July 24, 2010

    Hi Edgardo,
    you are correct. there is a mistake in the writeup.
    R5 is the current limitting resistance for the LED.
    output can be varied with R3(10K pot).

  • Edgardo Diolola
    July 24, 2010

    Here the out put voltage is set to 40 V by R5 & R8.If you want any other out put voltage use a 10 K pot instead of R5 and adjust it.

    Dear Admin,
    On the above quote, I am confused, I can not find R8, and R5 is a series resistor for LED (D3).
    Can you make clarification on this circuit?, I would like to build one for this.
    Thanks in advance.

  • June 21, 2009

    studentproject

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