18 Oct
2008
18 Oct
'08
9:19 a.m.
On Oct 18, 2008, at 1:50 AM, M H Stein wrote:
Brute-force linear is definitely the way to go.
I'd be tempted to grab a couple of filament transformers, a couple of
bridge rectifiers and some big caps. The great thing about S100
power supplies is that PSU regulation isn't important. A 6.3VAC
filament transformer hooked through a bridge rectifier and a big
electrolytic should be close enough. +/-16 could be furnished by a
small 12.6v transformer.
The real job of regulation is furnished on each board (usually
something like 78xx 79xx linear regulator ICs).
A misunderstanding, I think: he's talking about shorting out the
regulators on the *cards*, not in the PSU, and running regulated
+5 & +/-12 on the bus; should be doable with a heavy enough
bus and sufficient bypassing, in fact I think some manufacturers
did indeed do just that.
Hmm yes, upon giving the original message a second read, I'm sure
that's exactly what he meant.
The only drawback to his approach is that the boards will make
smoke if used in a "standard" S-100 chassis later on (in case someone
forgets).
-Dave
--
Dave McGuire
Port Charlotte, FL
Since I have
been unable to find any power supplies which provide
the +/- 8 and +/- 16 volts, I just thought of an idea the other day
of using a PC power supply and shorting out the on-board voltage
regulators to allow them to work at the +5V and +12V of the power
supply. In order to do that though, I would need a small (3-5
slot) motherboard to test a couple of cards together.
I don't think it's going to be possible to short around the +5
and
+12 regulators in a PC power supply, as they're not discrete in that
way. Your best bet (IMO) is to surf eBay for an big open-frame
linear power supply.