Comments on: Power Supply Circuit using LM 317

By: seetharaman

seetharaman — Sun, 30 Oct 2011 02:58:17 +0000

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

By: Leon Remp

Leon Remp — Sat, 29 Oct 2011 13:17:30 +0000

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

By: Seetharaman

Seetharaman — Fri, 27 May 2011 14:34:53 +0000

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

By: Frank

Frank — Thu, 26 May 2011 17:27:47 +0000

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)

By: admin

admin — Fri, 08 Apr 2011 10:40:47 +0000

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.

By: Frank

Frank — Thu, 07 Apr 2011 07:47:10 +0000

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

Thanks.

Frank

By: Edgardo Diolola

Edgardo Diolola — Sun, 25 Jul 2010 00:30:23 +0000

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

By: seetharaman

seetharaman — Sat, 24 Jul 2010 18:12:23 +0000

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).

By: Edgardo Diolola

Edgardo Diolola — Sat, 24 Jul 2010 15:18:27 +0000

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.

By: rajasekar

rajasekar — Sun, 21 Jun 2009 15:42:09 +0000

studentproject