From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Computer DC supplier
Date: Mon, 14 Oct 2002 17:17:51 GMT
NNTP-Posting-Date: Mon, 14 Oct 2002 10:17:51 PDT
Eitan Herman wrote:
> can i use computer supply to give 5v for my chips (standard chips like
> i can see from the specs that:
> RED : +5v 23A
> Yellow: +12v 8A
> Is the high current won't damage my ics ?, do i need the 7805 or can i
> count on the supplier 5v?
> In general, does a high current can damage my circuit , or , the ic
> will only demand the current it need?
> if you can, please point me to related documentation.
> ( i got the art of electronics, nothing there on this issue).
You may use such a supply, however, some of these supplies don't work
properly with small load currents. If yours misbehaves, connect it to an
old disk drive as a load as well.
Some of these supplies have an on/off switch. I have found the switch to
be unreliable beyond belief. Use an LED and a resistor as a pilot light
so that you don't accidentally hot swap parts.
I have yet to see one of these supplies with the 12 volts within
specification. If you use 12 volts for anything, consider that the power
supply may put out anything from 11 to 14 volts. Most likely seems to be
Although these supplies often work, they are not a substitute for a
proper metered lab supply. I have been hobbled with those PC power
supplies in the lab because of a particularly brain dead policy of the
engineering manager. In three years, in keeping three development
stations operational, we have consumed about a dozen of these supplies.
Most have been on/off switch failures and a few have been 12 volt output
below 10.5 volts.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org