Re: AT supply? - Increasing output the voltage.

From: mike (spamme0_at_juno.com)
Date: 08/26/04 

Date: Wed, 25 Aug 2004 19:30:38 -0700

Nico Coesel wrote:
> rpaisley4@cogeco.ca (Rob Paisley) wrote:
>
>
>>Would it be possible or practical to increase the output voltage on
>>the 12 volt line of an AT type power supply to 14 or 15 volts if the
>>output current was suitably de-rated.?
>>
>> The affect on 5 volt and other lines is of no concern in this
>>question.
>
>
> It has been done before by several people. It is not a difficult
> modification. Just use Google to find more information.
>

If you're gonna do this, measure the 5V output with the other 12V output
set at it's highest setting. Then compare that voltage to the voltage
rating of the 5V filter caps. You don't want them exploding on you.
Might also look at the ratings of all the other components in the system.

If you don't change the feedback to regulate the +12, your regulation
will be crap. If you do change the fedback, do a lot of tests with
various load transients to make sure the system is stable. If the
output turns out to have a big inductive reactance, load dumps will
give you big voltage spikes.

I'll try to verbalize my assumption...the way you asked the question
leads me to the assumption that you don't have the technical expertise
or equipment to evaluate the result. Yes, it can be done. Can YOU do it?

Bottom line is economics. Compare the $20 you saved on a power supply
to the replacement cost of the $2000 laptop computer you're testing. If
you like the odds, proceed.

mike 

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