Don —
I personally don’t like the idea of mixed chip orientation. I’ve done it in my own boards and subsequently revised it in later board revisions. Even though the silk screen is there, it’s too easy to make an honest mistake.
On my boards, I have the outline of the bypass cap touch the outline of the IC socket (I notice you have some space). It probably doesn’t save much, but every little bit helps I guess.
I am unsure about the 1:2 cap to IC ratio — I always learned 1:1 especially with TTL. They make (or used to make) IC sockets with the filter cap built into the socket. That’s not something I would usually have “in stock”. I think the ECB 68000 board has one cap inside the PLCC socket for the processor. You had to flatten it just right, but it worked fine.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
From: Don Caprio <ilv...@gmail.com>
Reply-To: S100-Post <n8vem...@googlegroups.com>
Date: Thursday, January 1, 2015 at 2:15 PM
To: S100-Post <n8vem...@googlegroups.com>
Subject: RE: [N8VEM-S100:5946] SOIC Packages For S100 Boards - Survey Question
Reply-To: S100-Post <n8vem...@googlegroups.com>
Date: Thursday, January 1, 2015 at 2:15 PM
To: S100-Post <n8vem...@googlegroups.com>
Subject: RE: [N8VEM-S100:5946] SOIC Packages For S100 Boards - Survey Question
Thanks for all the feedback. There were a lot of good arguments
for both sides. Each with it's own merit.
I think the consensus is stick with through-hole. I have to admit
that I'd hate to give up sockets. This is a good way to debug a
board and I'd hate to give that up. Plus I'm getting up there in age
as well and my eyes aren't what they use to be.
For my next version of the mini I do have some ideas to make
make more real estate available. The filer caps take up a lot of room.
I could go with a smaller footprint. I'm also wondering if one filter cap
could be used for 2, or 4 IC's. It's nice to have all the Pin 1's oriented
the same so that would blow that standard.
I've also seen the filter caps put in the center of the socket. I'm not fond of this idea.
Replace resistor nets with discrete and place resistor between LED's (yuck).
![]()
for both sides. Each with it's own merit.
I think the consensus is stick with through-hole. I have to admit
that I'd hate to give up sockets. This is a good way to debug a
board and I'd hate to give that up. Plus I'm getting up there in age
as well and my eyes aren't what they use to be.
For my next version of the mini I do have some ideas to make
make more real estate available. The filer caps take up a lot of room.
I could go with a smaller footprint. I'm also wondering if one filter cap
could be used for 2, or 4 IC's. It's nice to have all the Pin 1's oriented
the same so that would blow that standard.
I've also seen the filter caps put in the center of the socket. I'm not fond of this idea.
Replace resistor nets with discrete and place resistor between LED's (yuck).
-- Don Caprio ilv...@gmail.com
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