It is currently Sun Feb 28, 2021 1:26 pm

Click the link below to visit the site sponsor

The Ham Radio Shop




Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next
 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Convert a PSU
Hi Guys
I have a 13v 8 amp PSU i would like to Turn this into a variable PSU with a Volt and Watt Meter on
I will not need more that 13v max output just handy to have a Bench type psu that i can power my other projects off.

I have the Digital Volt and watt meter

Any body Point me in the direction to do this

The PSU has a Large Transformer

240 v to 13 i guess not measured this yet >

I an Tinkering with electronics and boards so thought this would be a good project to start with

I have just built This

http://1drv.ms/1LkjEyb

And got the Build Bug :)

Thanks again

Simon

_________________
M1BVX
2E1FON


Mon Oct 19, 2015 5:04 pm
Profile Send private message

 Convert a PSU 
Moderator
User avatar

Joined: Sun Aug 31, 2008 4:39 pm
Posts: 5548
Location: Sleaford, Lincolnshire (Bomber County) IO93TA WAB-TF04
Feedback: 0 (0%)
Reply with quote
Post Re: Convert a PSU
Something like this cct using an lm317t variable voltage regulator should fit the bill.

http://www.sentex.ca/~mec1995/circ/VarReg1/VarReg1.html

There are many variations on the theme if you google 'variable voltage psu circuit'

Or the 338 chip for higher amperage - both available from here:- http://www.bowood-electronics.co.uk/ind ... le-c-24_97

Best of luck, let us know how it goes. :good:

_________________
73 de Alan.

Today I broke my personal record for the most consecutive days alive, despite Covid 19 - I hope to better it again tomorrow.


Last edited by G0BXU on Mon Oct 19, 2015 7:48 pm, edited 1 time in total.



Mon Oct 19, 2015 7:45 pm
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Re: Convert a PSU
Sure will

Big Thanks

Simon
M1BVX

_________________
M1BVX
2E1FON


Mon Oct 19, 2015 7:47 pm
Profile Send private message

 Convert a PSU 
Moderator
User avatar

Joined: Sun Aug 31, 2008 4:39 pm
Posts: 5548
Location: Sleaford, Lincolnshire (Bomber County) IO93TA WAB-TF04
Feedback: 0 (0%)
Reply with quote
Post Re: Convert a PSU
Just edited my post Simon.....check out Bowood for supplies of all types.

_________________
73 de Alan.

Today I broke my personal record for the most consecutive days alive, despite Covid 19 - I hope to better it again tomorrow.


Mon Oct 19, 2015 7:49 pm
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Re: Convert a PSU
thanks alan :)

Simon

_________________
M1BVX
2E1FON


Mon Oct 19, 2015 8:50 pm
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Mon Dec 08, 2014 9:46 pm
Posts: 555
Location: Haslingden, Lancashire
Feedback: 0 (0%)
Reply with quote
Post Re: Convert a PSU
Perhaps leave the existing circuit for your main supply and add additional smaller regulated circuits for variable, 5v, 9v supplies etc.
There are ample regulators available for this.


Tue Oct 20, 2015 7:02 am
Profile Send private message

 Convert a PSU 
Contributor 2020
User avatar

Joined: Sat May 23, 2009 1:46 pm
Posts: 22315
Location: Shropshire UK IO82TN
Feedback: 6 (100%)
Reply with quote
Post Re: Convert a PSU
Or use the LM 317 to control a suitable pass transistor, for variable voltage at your full PSU current availability.
On its own it does have a 1.5 amp limit of course.
You will probably find the PSU's voltage directly after the bridge rectifier is in excess of its rated 13 volts output, and is regulated down possibly with a simple zener diode circuit, so once finished your variable PSU will go from 1.2 volts to in excess of its designed 13 volts.
If you want to limit its top end voltage, you could incorporate a preset maximum control in the regulators voltage control components.

_________________
Dave G0BHD.
Been there and got the T shirt, sadly like the T shirt the memory of it has long since faded, gone rather tatty, and finally been consigned to the bin!


Tue Oct 20, 2015 7:38 am
Profile Send private message

 Convert a PSU 
Contributor 2020
User avatar

Joined: Sat May 23, 2009 1:46 pm
Posts: 22315
Location: Shropshire UK IO82TN
Feedback: 6 (100%)
Reply with quote
Post Re: Convert a PSU
A simple version of the pass transistor circuit:
Attachment:
lm317.gif
lm317.gif [ 12.55 KiB | Viewed 2760 times ]

And the first parts of this article cover the LM317, and using it with a PNP pass power transistor, the 2N2955, as oposed to the NPN 3055 circuit shown above.
It goes on to describe feeding the regulator from a seperate transformer winding to the pass tansistors (2N3055 NPN), each with their own rectifiers and smoothing caps, which can help high current efficiency.

http://www.ee.teihal.gr/labs/electronic ... ulator.pdf

_________________
Dave G0BHD.
Been there and got the T shirt, sadly like the T shirt the memory of it has long since faded, gone rather tatty, and finally been consigned to the bin!


Tue Oct 20, 2015 8:02 am
Profile Send private message

 Convert a PSU 
Contributor 2021
User avatar

Joined: Tue Oct 09, 2012 1:09 pm
Posts: 12135
Location: West Midlands
Feedback: 114 (100%)
Reply with quote
Post Re: Convert a PSU
There's a power supply on here http://g.zs5wo.net/ I built one with a 317 in place of the 7812 (and leave out the diodes and capacitor on the ground of the 7812) and it worked fine.
It was only a 4A transformer, so I only used one transistor without the emitter resistor, and the soft start, over voltage and fan control parts were not needed, which made it very simple.

At 8A it would be best with two transistors, and the emitter resistors would then be needed.

_________________
===================
Gee Three Eee Jay Ess - RSGB, SARL, EPC
My email address is correct on QRZ.com
===================


Tue Oct 20, 2015 8:09 am
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Re: Convert a PSU
many thanks guys will report back once i start building not going to convert but build from scrach :)
some great ideas here

thanks again

Simon

_________________
M1BVX
2E1FON


Tue Oct 20, 2015 9:02 pm
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Wed Jun 13, 2012 6:15 pm
Posts: 111
Location: Newport Shropshire
Feedback: 0 (0%)
Reply with quote
Post Convert a PSU
Hi

Sorry it`s a bit late just seen the topic on here.

http://www.banggood.com/0-30V-2mA-3A-Ad ... 58308.html

I have just built the above kit. It needs a 24v ac supply. If you need any more info contact me. iv`e written a bit about it
for the local clubs news letter.

Cheers

Paul

m0pnn


Thu Oct 29, 2015 8:46 pm
Profile Send private message

 Convert a PSU 
Contributor 2020
User avatar

Joined: Sun Jul 22, 2007 6:06 pm
Posts: 1285
Location: IO71PV Efailwen
Feedback: 84 (100%)
Reply with quote
Post Re: Convert a PSU
Quote:
Hi

Sorry it`s a bit late just seen the topic on here.

http://www.banggood.com/0-30V-2mA-3A-Ad ... 58308.html

I have just built the above kit. It needs a 24v ac supply. If you need any more info contact me. iv`e written a bit about it
for the local clubs news letter.

Cheers

Paul

m0pnn


I've just ordered one looks good for my test power supply.

_________________
MARK 2W0JMK
LOC:- IO71PV WEST WALES

__________________
.........._______
.....___/|__|__|\____
.=.( _---\__|___|_---_)
.........O..2W0JMK..O....


Fri Oct 30, 2015 8:46 am
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Re: Convert a PSU
m0pnn wrote:
Hi

Sorry it`s a bit late just seen the topic on here.

http://www.banggood.com/0-30V-2mA-3A-Ad ... 58308.html

I have just built the above kit. It needs a 24v ac supply. If you need any more info contact me. iv`e written a bit about it
for the local clubs news letter.

Cheers

Paul

m0pnn


LOL got one of these to build this weekend :)

I am going to see if i can mod it and have a volt and amp meter on it

Simon

_________________
M1BVX
2E1FON


Fri Oct 30, 2015 8:53 am
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Wed Jun 13, 2012 6:15 pm
Posts: 111
Location: Newport Shropshire
Feedback: 0 (0%)
Reply with quote
Post Re: Convert a PSU
Hi

Simon

That`s what | have done added a current and volt meter it works well. I swapped the 7824 for a 7812 so I could run the voltmeter/amp meter. I used a computer CPU cooler for the main transistor cooler. The transformer I used had taps for 12v/24v. I built a bridge rectifier for the 12v tap so I could run a three old computer fans for cooling.

Cheers

Paul

m0pnn


Fri Oct 30, 2015 11:13 am
Profile Send private message

 Convert a PSU 
Advanced Member

Joined: Sun Aug 03, 2014 8:28 pm
Posts: 128
Location: Keighley IO93AU
Feedback: 31 (100%)
Reply with quote
Post Re: Convert a PSU
m0pnn wrote:
Hi

Simon

That`s what | have done added a current and volt meter it works well. I swapped the 7824 for a 7812 so I could run the voltmeter/amp meter. I used a computer CPU cooler for the main transistor cooler. The transformer I used had taps for 12v/24v. I built a bridge rectifier for the 12v tap so I could run a three old computer fans for cooling.

Cheers

Paul

m0pnn



HI Paul Have you any Pics so i can see how the Meter is wired up :)

I just need to find a Power source for this will look for a 7812 chip

Thanks again

Simon

_________________
M1BVX
2E1FON


Fri Oct 30, 2015 1:15 pm
Profile Send private message
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next


Who is online

Users browsing this forum: No registered users and 0 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB © phpBB Group.
Designed by Vjacheslav Trushkin for Free Forums/DivisionCore.