Convert comp PS to variable

[Robert Darrens]

I have a two good quality AT computer power supplies (Ipec) and would
like to convert them to variable power supplies for bench use.

Is this a simple as wiring an LM317 type circuit to one of the 12V
outputs?

Secondly, is it possible to add the outputs for more voltage?

For example, the 5 and 12V outputs in one unit or the 12V of two units
in some kind of series arrangement.

Thank you for any suggestions.

Robert

 

[mike]

Robert Darrens wrote:

I have a two good quality AT computer power supplies (Ipec) and would
like to convert them to variable power supplies for bench use.

Is this a simple as wiring an LM317 type circuit to one of the 12V
outputs?

Secondly, is it possible to add the outputs for more voltage?

For example, the 5 and 12V outputs in one unit or the 12V of two units
in some kind of series arrangement.

Thank you for any suggestions.

Robert

There are exceptions, but generally, a computer supply makes a lousy
bench supply.
If a LM317 will do what you want, it's easier to start with a small
transformer and skip the computer supply altogether.
You might get better advice if you stated the voltage/current ranges you
need along with other specs like what kind of current limit you need,
temperature stability, line/load regulation, noise you can tolerate, etc.

Computer supplies make great...computer supplies.
mike

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[kmaryan@gmail.com]

I don't know the specifics, but as I understand it a computer supply is
designed to work at some minimum load, otherwise they tend to be fairly
lousy supplies. So unless you want to drop 50W or whatever across a
resistor, it's not a good idea.

Chris

 

[Tim Wescott]

Robert Darrens wrote:

I have a two good quality AT computer power supplies (Ipec) and would
like to convert them to variable power supplies for bench use.

Is this a simple as wiring an LM317 type circuit to one of the 12V
outputs?

Secondly, is it possible to add the outputs for more voltage?

For example, the 5 and 12V outputs in one unit or the 12V of two units
in some kind of series arrangement.

Thank you for any suggestions.

Marlin P Jones, and All Electronics IIRC have very nice 120V in 12V out

switchers that are actually designed to put out substantial power it
12V. They're surplus so they're not too expensive.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Tam/WB2TT]

<kmaryan@gmail.com> wrote in message
news:1109341777.847242.288160@g14g2000cwa.googlegroups.com...

I don't know the specifics, but as I understand it a computer supply is
designed to work at some minimum load, otherwise they tend to be fairly
lousy supplies. So unless you want to drop 50W or whatever across a
resistor, it's not a good idea.

Chris

Generally the minimum load has to be applied across the +5V output. The

reason for this is that the feedback is taken from 5 Volts. Supposedly,
*some* supplies will work with a load of as little as 1 Amp.

Tam