Re: 12 volt power source?

On Fri, 21 Dec 2007 23:55:37 +0100, I said, "Pick a card, any card"
and "Klaus D. Mikkelsen" <er.du.saa.klog@xxxxxxxxxxxxxxxx> instead
replied:

Ray Haddad skriver:

Multimeters don't apply much of a load by design. My claim was based
on a statement that the voltage on a 12 volt supply read more than
12 volts. Made by another poster, not me. I know for a fact, and
based on your experiences stated below, that this is common with
some poorly designed or special purpose power supplies. They rely on
the load to have full regulation. It saves the manufacturer money.

We totally agreee......

Shitty powersupplies depend on load, but regulated doesnt.

Most here seem to be hunting the cheapest of the cheap and probably
buy the wall wart type. More than half of those are only partially
regulated relying on the equipment on the load side to finish the
regulation. Awful practice, that, but it does make for cheap power
supplies when you need them.

I've only got 40 years. Tubes were on the way out and transistors
were very expensive back then. Integrated circuits were only dreams
but they did exist when I started out. Built my first S-100 machine
from scratch using a brand shiny new, Z80 (Soooooo expensive!).

Darn - Z80 was in my youth (I'm "only" 35:-)

I nearly used an 8080A but the Z80 came available and I switched.
All wire-wrapped. What a headache that was. Tedious but fun.

Did you ever get the ZX spectrums ?
http://www.worldofspectrum.org/
AFAIR it was british build and based on the Z80A. They keyboard was
rubber and was later used as "anti slip mats in showers" :-)

I had a Sinclair ZX80, the membrane keyboard type. Designed a 64k
memory expansion for it and published the design in the old Popular
Electronics magazine sometime in the '80s. I forgot which name I
published under for that one. I use pen names mostly to avoid flame
wars here on USENET over something I publish.

I only do design work for myself now. I teach a bit at the local
tertiary schools here in Perth whenever I'm asked. I am a former
third party rep for MicroChip but gave it up when I moved to
Australia from San Diego. I truly love embedded control and use any
excuse at all to drop a PIC into a project.

Neat :-)

Well done.

Thanks. Another of my proud job was a late night, we were pretty drunk,
when my friend pulled out an DVD player with defective switchmode
powersupply. It took about 10 minutes and then it was running again -
typical error, toasted power diode and dead capacitors.....
The next morning i had headache......

I picked up a dead, second-hand, rack mounted P4 Quad Core PC used
for 6 months as a server before it failed. It was failing big time
according to the seller and I verified that. But, his company had
replaced it with a bigger and better server with 4 terabytes of hard
drive. This one had 4 320GByte ATA/IDE drives, 2 500GByte SCSI
drives, 2 SCSI controllers and a 4 port RAID controller. On
inspection, I found a lightning damaged burned trace at the DMA
controller chip and fixed the unit. It's a screamer with more hard
drive space than I can use in a lifetime. It cost me a whopping
$10.00 yesterday. I wiped all the drives clean as promised.

Now, what shall I do with it? I think I'll sleep on it. It has sharp
pointy corners but with a thick enough blanket I can at least have a
nap on it.

Oh, rats. I meant to send this by e-mail but it's too much bother to
retype it or cut and paste it. So, it goes on the newsgroup with a
copy by e-mail. Sorry it's so horribly off topic, guys.

Well, I can make it on topic easy enough. I believe I'll use that
new PC to automate my trains. There. On topic now.
--
Ray
.

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