Lets start again I would like to make an adjustable power suply 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

On Mon, 09 Jun 2008 21:28:46 +1000, F Murtz
wrote:

Lets start again I would like to make an adjustable power suply 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

As Phil says, the classic approach to this is an LM723 (aka uA723
etc.). It is (now "was"?) the guts inside many, many benchtop variable
supplies with adjustable voltage and current limiting. The data sheets
have typical application schematics, including those with a pass
transistor to support higher currents.

--
Rich Webb Norfolk, VA

"Rich Webb" wrote in message
...
On Mon, 09 Jun 2008 21:28:46 +1000, F Murtz
wrote:

Lets start again I would like to make an adjustable power suply 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

As Phil says, the classic approach to this is an LM723 (aka uA723
etc.). It is (now "was"?) the guts inside many, many benchtop variable
supplies with adjustable voltage and current limiting. The data sheets
have typical application schematics, including those with a pass
transistor to support higher currents.

--
Rich Webb Norfolk, VA


I suggest that you visit the page at
http://www.repeater-builder.com/astr...ron-index.html. That site has a good
bit of info on Astron power supplies, their quirks and a few mods that can be
added to them. There's also a bunch of schematics toward the bottom of the
page. I suggest that you read that page thoroughly, including the datasheet for
the LM723 regulator that's used in Astron's linear supplies to get some ideas
about something that you can build that will actually work.
With your transformer, you will start with the lower power units (20-30 watts).
With a full wave bridge rectifier, capacitor input filter, your power supply
will only put out around 2.8 amps. Allowing for low line, ripple and regulator
headroom, the max voltage output that you can expect will be about 20-22 volts.
Most of Astron's supplies have current limiting, and some have adjustable
limiting.

When you've done a little homework there, you can come back with some more
specific questions.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want