2 Jun
2007
2 Jun
'07
9:33 p.m.
Roy,
Thanks for the input. I was thinking about including one with vertical
rows and one with horizontal rows. That way you can have some flexibility.
One of the recent options for the onboard power supply was to use a low
dropout voltage regulator. This allowed boards to be installed in S-100
systems which contained either the original S-100 specs or the IEEE-696
specs. The latter have a lower power supply voltage on the
backplane(translates to lower power consumption) which an ordinary 7805
voltage regulator can't accept. These require at least a 10+ volts on
the backplane just to get a regulated 5V output. The LO voltage
regulators need only about 7V input to get a regulated 5v output.
The original backplanes were only 2 layer and couldn't handle the
current capacity. The local(distributed) voltage regulators were the
only option. You need at least a 4 or 6 layer backplane with a separate
copper layer for each voltage and then a layer for ground to have enough
copper for all that current.
=Dan
[ My Corner of Cyberspace http://ragooman.home.comcast.net/ ]
Roy J. Tellason wrote:
Hmm, good question!
I have currently only two S-100 systems, a Cromemco System 3 with problems in
the PersSci drive. The floppy that was in the drive when I got it had been
in there and run so long that you could see clearly through the track zero
location. :-) I have some data on this stuff somewhere, and it appears
that they're using incandescent bulbs for such stuff as index sensors and
such? And the Imsai, here.
Got a Vector S-100 backplane too, that I've started to build, only I lack a
few parts. Most importantly the S-100 connectors themselves. :-(
I also have a couple of prototyping cards, I *think* they're Vector as well,
but haven't done anything with 'em yet to come up with a preference. I guess
vertical rows makes more sense in terms of air flow for heat dissipation?
That for the heatsinks for sure, though a lot of systems I saw mention of
later on in the popular period for S-100 seemed to be inclined to put a
regulated switching power supply in place and simply jumper across the
regulator positions. I dunno, to me the distributed approach always made a
lot of sense.