12 May
2006
12 May
'06
4:01 p.m.
Rumor has it that Brian L. Stuart may have mentioned these words:
I was thinking of that (and was also suggested by a cow-orker) but I was
unsure about how to handle the function of variable resistance WRT heat
dissipation; and also, if a bulb fails, it fails open-circuit which means
there's no more voltage regulation. I suppose with enough bulbs, one could
build enough redundancy into the system...
I may hit an auto-parts store tomorrow anyway and see what I can scare up;
but having ready access to several CPUs (2 each 80486SX's & a P75 Overdrive
on a quick search) I figured that a 5V CPU would be a good way to dissipate
power from a 5V source, and the 486 would prolly have the highest current
draw of any easily available 5V processor.
But again, I could very well be wrong...
No, I'm *not* using any of my 6809s!!! ;-)
Thanks!
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Bugs of a feather flock together."
sysadmin, Iceberg Computers | Russell Nelson
zmerch at 30below.com |
From: Roger
Merchberger <zmerch-cctalk at 30below.com>
The problem is I need to use a PC power supply (AT-class with it's own
power switch) as a 12V power source, and the only one I have access to
needs a minimum load of 3Amp on the +5Volt line.
How about a light bulb? 
12 May
12 May
4:17 p.m.
Roger Merchberger wrote:
Rumor has it that Brian L. Stuart may have mentioned
these words:
I may hit an auto-parts store tomorrow anyway and see
what I can scare
up; but having ready access to several CPUs (2 each 80486SX's & a P75
Overdrive on a quick search) I figured that a 5V CPU would be a good way
to dissipate power from a 5V source, and the 486 would prolly have the
highest current draw of any easily available 5V processor.
I'm not sure, but I'm thinking that a CPU connected to a power supply
would not draw all that much power if there wasn't a clock signal to
really cause it to heat up. I'm just talking off-the-cuff here, but I
believe you'd have essentially a resistor attached to your power supply.
I'm not eletrical engineer, so take that with a grain of salt but I'm
using the emperical view of heat generation vs clock speed.
Barry
5:24 p.m.
On Fri, 12 May 2006, Roger Merchberger wrote:
Rumor has it that Brian L. Stuart may have mentioned
these words:
I was thinking of that (and was also suggested by a cow-orker) but I was
unsure about how to handle the function of variable resistance WRT heat
dissipation; and also, if a bulb fails, it fails open-circuit which means
there's no more voltage regulation. I suppose with enough bulbs, one could
build enough redundancy into the system...
I may hit an auto-parts store tomorrow anyway and see what I can scare up;
but having ready access to several CPUs (2 each 80486SX's & a P75 Overdrive
on a quick search) I figured that a 5V CPU would be a good way to dissipate
power from a 5V source, and the 486 would prolly have the highest current
draw of any easily available 5V processor.
But again, I could very well be wrong...
No, I'm *not* using any of my 6809s!!! ;-)
Thanks!
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | "Bugs of a feather flock together."
sysadmin, Iceberg Computers | Russell Nelson
zmerch at 30below.com |
A bare 486 will probably not draw enough power, especially if it not on a
working motherboard (its 1u CMOS so mainly draws dynamic power - no clock - no
power)
Peter Wallace
From:
Roger Merchberger <zmerch-cctalk at 30below.com>
The problem is I need to use a PC power supply (AT-class with it's own
power switch) as a 12V power source, and the only one I have access to
needs a minimum load of 3Amp on the +5Volt line.
How about a light bulb?
5:52 p.m.
Rumor has it that Peter C. Wallace may have mentioned these words:
A bare 486 will probably not draw enough power,
especially if it not on a
working motherboard (its 1u CMOS so mainly draws dynamic power - no clock
- no power)
OK, believe it or not, RatShack may have had what I need in enough quantity
(Gasp) so I think I'm covered there. They had 1 Ohm 10W power resisters,
2/pack for $1.79. 5 packs, that should get me going. (I may have to set up
2 PS's).
As an offtopic question: how much heat will the sand/cement-type wirewound
resistors emit? Can I heat-shrink 2 of them together and be OK, or will it
get too hot & melt/crack the tubing? I'm thinking "small modules" of 2
each
of these... fewer connections floating around is good. ;-)
The PS wanted 3A at 5V, and the hard drives (working or otherwise) I had
kicking around only ate .7A to .8A each, so I'd have needed 4+ of them -
assuming they'd draw that much current w/no 12V going to it.
WRT the CPU needing a clock - I could grab a 5V can oscillator from a dead
mobo & feed it a clock... Maybe I'll diddle with that *anyway* just because
I'm durned curious now... ;-) Just think: A variable dummy load; set it to
how much power you want it to eat just by changing the oscillator... ;-) I
was not told what kind of enclosure this was going in, so I didn't know if
there'd be room for the whole mobo; or used headlamps, or... which is why I
was thinking CPU.
Ah well... thanks for all the advice, guys!
Laterz,
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger -- SysAdmin, Iceberg Computers
zmerch at 30below.com
Hi! I am a .signature virus. Copy me into your .signature to join in!
13 May
13 May
2:31 p.m.
On Friday 12 May 2006 05:52 pm, Roger Merchberger wrote:
As an offtopic question: how much heat will the
sand/cement-type wirewound
resistors emit?
How much power are they dissipating?
Can I heat-shrink 2 of them together and be OK, or
will it get too hot &
melt/crack the tubing? I'm thinking "small modules" of 2 each
of these... fewer connections floating around is good. ;-)
I would omit the heatshrink to favor air flow removing that heat.
The PS wanted 3A at 5V, and the hard drives (working
or otherwise) I had
kicking around only ate .7A to .8A each, so I'd have needed 4+ of them -
assuming they'd draw that much current w/no 12V going to it.
WRT the CPU needing a clock - I could grab a 5V can oscillator from a dead
mobo & feed it a clock... Maybe I'll diddle with that *anyway* just because
I'm durned curious now... ;-) Just think: A variable dummy load; set it to
how much power you want it to eat just by changing the oscillator... ;-) I
was not told what kind of enclosure this was going in, so I didn't know if
there'd be room for the whole mobo; or used headlamps, or... which is why I
was thinking CPU.
I'd start small and add only bits at a time until you figure out what you
need. You may be able to get away with less than you think might be
necessary.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
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