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animation project from hell
Well, I'm not usually one to broadcast my screw ups but I thought I would
relate a little story that might save someone out there some time.
I'm currently working on a "art" piece that uses 5 solid state transformers
from Information Unlimited. The xformers are good and very inexpensive.
The animator is a Basic Stamp from Parallax controlling npn darlingtons
to switch the 12 volt supply. Well, three of the xformers take 500ma each
in a contiuous mode. I thought I would cheat and get by with about 1 amp
if I pulsed the xformers with a low duty cycle, and a couple of other tricks.
I have my PC hooked up to the stamp, a separate bench supply for the
12v and had noticed frequent stamp lockups that went away when I disconnected
the programming cable. One should pay attention to these hints! Last night about
1am I am getting pretty sick of this project which has to hang tonight; I don't
have a 2 amp 12V supply, and the high voltage and the swithing transients are killing
my stamp so fast I can't get anything to work right, and still have at least two coats
of paint that have to be put on. I thought to myself; "self, just
ground the 12 v supply to the PC and you'll be ok", but do I listen? No and before
I could take one more sip of tequilla, BANG, my parallel port dies on the PC. No
more midnight+ programming, and no printing for a while.
The morals are these:
1. Don't ignore flakey symptoms.
2. If your too lazy to use opto isolators in your animator at least make
a good solid ground between all circuits, and the PC.
3. Get the right power supply to begin with, even if you have to lower yourself
and go to radio shack.
4. Thank Parallax for putting in very good circuit protection into the Stamp.