Hi all, I am building a power supply for annodizing. I have a 240v to 2x25A transformer but at the moment I only do quite small parts which I use about 5Amps. But I would like to be able to do larger parts
I have found a simple circuit which I want to use, do you think this would work? Is the Led in the circuit just to show power is on?
I would like to add an led to show current limiting is on, how do I do that?

http://hmin.tripod.com/als/andysm/drawings/supplies/ps2-30v.gif

Sorry but I can't post a picture of the circuit from my phone but it's the 8th schematic in the list(labeled 3 of 4) stabilized.
Thy this link not sure the first link works
http://hmin.tripod.com/als/andysm/drawings/supplies/ps2-30v.gif
Thanks for your time.
Ceefna

 

Try this
http://hmin.tripod.com/als/andysm/pages/analogs3.html

It's the 8th schematic down the page. Sorry about the links my phone won't let me copy them.

Ceefna

 

Have got the schematic now, please can somebody advise me on my original questions. Also do the 2N3055's need to be insulated from the heat sink? and does the BD243C need to go on the heat sink?

Thanks

Ceefna

 

For the 2n3055's and the BD243C, not if the heat sink is insulated from everything else. It will have +40VDC on it with respect to ground. Depending on your physical design of the installation that may or may not be a safety issue.

Ken

 

How does it regulate current? It doesn't look like an anodising supply juts an adjustable voltage supply.

You will likely need more than 30v available too if you want to anodise well.

 

ceefna , the scheme you choose is a simple voltage regulated, current limited Power supply. It is not a good choice for your deal.
Mainly it have a poor current regulation because it try to sense the current with all the Vbe of 3055 and BC within the net, that (Vbe) change a lot with temp. It seems it try to sense de current measuring the voltage over the emitter resistance who's mainly purpose is to split the current within the 3 transistor equally.
You must see the maximum DC input voltage in order to define the Heathsink and to choice an schem that senses the current with a "dedicated" resistor to do so.(it is common to use a Four terminal resistor or a current shunt).
It is preferable to use an isolation (between transistor and heath sink) in any schem you choose , for safety reasons.
good luck