Circuit diagram (5A PSU) - UK Vintage Radio Repair and Restoration Discussion Forum

ex 2 Base · 12th Jul 2021, 6:09 pm

I would like a circuit diagram of a variable voltage bomb proof 5 amp power supply for general use in my workshop. I have some 1.5 amp LM317 and several 2N3055 transistors and thought they might combine together .Ted

Station X · 12th Jul 2021, 7:16 pm

Voltage?

G6Tanuki · 12th Jul 2021, 7:31 pm

If you want some good design hints, search out the PW "Marchwood" PSU.

ex 2 Base · 13th Jul 2021, 10:36 am

Sorry folks I forgot the voltage, 1.5 around 30 and variable. I did make the Marchwood all those years ago. I might still have the circuit diagram some where. Ted

60 oldjohn · 13th Jul 2021, 10:26 pm

If anyone needs it here is the PW Marchwood part 1 https://worldradiohistory.com/UK/Pra...01983%2006.pdf and part 2 https://worldradiohistory.com/UK/Pra...01983%2007.pdf

John.

Radio Wrangler · 13th Jul 2021, 11:19 pm

Quote:

Originally Posted by ex 2 Base

Sorry folks I forgot the voltage, 1.5 around 30 and variable.

He's asking for a design for a lab type variable power supply. Not a 13.8v supply for amateur radio gear.

Likely places to find one would be in the pages of Elektor, or in the applications notes from the usual semiconductor firms... and The Art of Electronics. Wireless worls is a 'maybe'.

The low voltage end is the design difficulty and the power dissipation may be a problem.

David

Mooly · 15th Jul 2021, 8:04 pm

Why not just look at the examples in the data sheet. There is an adjustable supply using external NPN's and also a variable voltage supply with adjustable current limit although that one uses PNP pass transistors.

ronbryan · 15th Jul 2021, 11:25 pm

I suggest you have a look at the Farnell L30E circuit. This is a well designed 0-30V 5A power supply, using discrete components. I think the L30/5 is the same circuit. The hardest item to find is the mains transformer, if you really want a 5A supply as a second secondary winding is required for the control electronics.

Ron

majoconz · 16th Jul 2021, 1:50 am

A very good power supply construction article by J. L. Linsley-Hood appeared in the Wireless World for January 1975. With the aid of a class of would-be technicians we made four of these power supplies for class use which were almost indestructible. The students had to be instructed that you do not reduce the output voltage to zero by turning off the power switch and vice versa!
I also made one for home, a very modified single sided, which happily supplies more than 12 Amps with excellent regulation on a large heatsink.
The J.L. L-H article is attached. Page 3 is a jpeg - the original article had a large picture that exceeded the pdf file limit.

Terry_VK5TM · 16th Jul 2021, 4:45 am

Page 3 of the power supply as pdf.

12th Jul 2021, 6:09 pm	#1
ex 2 Base Heptode Join Date: Nov 2009 Location: Scarborough, North Yorkshire, UK. Posts: 510	Circuit diagram (5A PSU) I would like a circuit diagram of a variable voltage bomb proof 5 amp power supply for general use in my workshop. I have some 1.5 amp LM317 and several 2N3055 transistors and thought they might combine together .Ted

12th Jul 2021, 7:16 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Circuit diagram Voltage? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

12th Jul 2021, 7:31 pm	#3
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,007	Re: Circuit diagram If you want some good design hints, search out the PW "Marchwood" PSU.

13th Jul 2021, 10:36 am	#4
ex 2 Base Heptode Join Date: Nov 2009 Location: Scarborough, North Yorkshire, UK. Posts: 510	Re: Circuit diagram Sorry folks I forgot the voltage, 1.5 around 30 and variable. I did make the Marchwood all those years ago. I might still have the circuit diagram some where. Ted

13th Jul 2021, 10:26 pm	#5
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,988	Re: Circuit diagram If anyone needs it here is the PW Marchwood part 1 https://worldradiohistory.com/UK/Pra...01983%2006.pdf and part 2 https://worldradiohistory.com/UK/Pra...01983%2007.pdf John. __________________ My favourite text message "I'll be there in five minutes, if not read again"

15th Jul 2021, 8:04 pm	#7
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,351	Re: Circuit diagram Why not just look at the examples in the data sheet. There is an adjustable supply using external NPN's and also a variable voltage supply with adjustable current limit although that one uses PNP pass transistors. Attached Thumbnails

15th Jul 2021, 11:25 pm	#8
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Re: Circuit diagram I suggest you have a look at the Farnell L30E circuit. This is a well designed 0-30V 5A power supply, using discrete components. I think the L30/5 is the same circuit. The hardest item to find is the mains transformer, if you really want a 5A supply as a second secondary winding is required for the control electronics. Ron Last edited by ronbryan; 15th Jul 2021 at 11:39 pm.