🚀 go-pugleaf

On Wed, 11 Jun 2008 11:24:33 +1000, F Murtz <haggisz@hotmail.com>
wrote:

>F Murtz wrote:
>> I would like to make an adjustable power supply using a transformer with 
>> a 24v 5a single wound secondary I would like the voltage to be 
>> adjustable from lowest to highest possible given transformer I would 
>> like to have regulated current
>> 
>> There is another possibility I also have a larger transformer with two 
>> 32v 4.7a secondaries If anyone has a schematic for an adjustable power 
>> supply with adjustable current regulation making the most of the 
>> transformer specs I would be eternally grateful
>
>
>Thanks to every one for their help on power supply design from spec 
>sheets etc but I was hoping for an already designed circuit

It would be a pity, putting together your first power supply without
taking the oportunity to learn something about it. I mean - what are
you going to be using the completed power supply for, if not as a
learning tool?

A fair supply of app notes are available on the web to help you do
this, in consideration of the fact that you want to tailor the circuit
to transformers that you already have. Normally you wouldn't purchase
a part before you had some idea of what you needed, to do what you
aimed to do.

http://www.ieeta.pt/~alex/docs/ApplicationNotes/Rectifier%20Applications%20Handbook.pdf

A kit or pre-built/surplus unit may be an obvious alternative to the
bulk of all this 'learning' stuff. Even then, getting what you need
still requires an aim, to specify a requirement.

One kind of regulation method that is fairly tolerant of transformer
fixed winding voltages is illustrated at 

http://members.shaw.ca/legg/1991a.html

This also offers a pspice simulation that runs in the free SWCADIII
package from Linear Technology. It takes a lot more savy to graft
regulation circuits onto un-anticipated transformers than it does to
design for a transformer from scratch, or fit a properly configured
transformer into a pre-designed configuration. 

RL