RE: [N8VEM-S100:3967] Power distribution across an S100 Board and voltage issues with TO-3 Regulators..

I only have 17 of them, I'm keeping 3 for my own future repairs as needed. That leaves 14 that I'm willing to sell off. And those got spoken for very quickly. Perhaps I should limit everyone to 3?

From: mon...@vitasoft.org
To: n8vem...@googlegroups.com
Subject: RE: [N8VEM-S100:3967] Power distribution across an S100 Board and voltage issues with TO-3 Regulators..
Date: Wed, 4 Jun 2014 20:04:36 -0700

Josh I don’t want to be a hog but I’ll take up to 10 if you have them, I don’t want to hassle with this again.

However I want to be sure others can get theirs, so deal with them first, any left after that , I’ll take up to, say 10.

John

From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Crusty OMO
Sent: Wednesday, June 4, 2014 6:26 PM
To: n8vem...@googlegroups.com
Subject: RE: [N8VEM-S100:3960] Power distribution across an S100 Board and voltage issues with TO-3 Regulators..

Hi John,

I have a bunch of LM323K's, I can sell them off for $2 if anyone is interested. I'll even test them quickly to be sure they aren't putting out crap.

Cheers,
Josh

Date: Tue, 3 Jun 2014 00:01:57 -0700
From: mon...@vitasoft.org
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:3912] Power distribution across an S100 Board and voltage issues with TO-3 Regulators..

Does anybody know how much tolerance 74xx TTL chips have to a situation where on the LHS of the board near the V regulator is 5.13 volts while on the extreme RHS the voltage has dropped to 5.03 volts. This is the new 80386 board which draws a fair amount of current.

See here:-

http://s100computers.com/My%20System%20Pages/80386%20Board/80386%20CPU%20Board.htm

I am using a 78H05 TO-2 regulator (Fairchild). Even though these regulators are hard to find, with their heat sink they run nice and cool. Is the above acceptable both in terms of voltage gradient and absolute number i.e. >5V.

While on TO-3 5V regulators, I have been plagued with "no name brands" that either quickly die or are way outside what they should be in terms of voltage.

Just yesterday I got 2 "LM323K's (5V, 3A) from Unicorn. One put 6.2 volts on a test board!!!! I had others from Jameco that put out 4V's.

Since a couple of our recent S100 board use these regulars, please test them first. Mouser stopped carrying the LM323's. If anybody has a good source to name brand 78H05's or LM323's please let us know.

I'm reluctant to go with two L7805ACV's TO-220 (5V 1.5A) because they use up so much board space with their heat sinks.

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