Envelope-to: craig@sbc-85.com
Delivery-date: Mon, 06 Mar 2023 17:36:42 -0600
Subject: Re: 8 slot SBC-85 backplane
To: craig@sbc-85.com
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From: denverh <denverh2000@gmail.com>
Message-ID: <c3c338eb-2328-9251-bc5c-4e1954597f75@gmail.com>
Date: Mon, 6 Mar 2023 17:36:28 -0600
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craig@sbc-85.com wrote:
> Hi Denver, thanks for the input.
>
> I had a question about what you are saying regarding the +5V being less=
 practical with more slots?  I usually just use 5V wall warts or desktop =
power bricks and have not had any problem with my larger multibus or STD =
systems, so I think I must have missed your point about the 12 or 15V inp=
ut.
Oh it wasn't really based on any measurements or calculations, but I=20
thought that if you had a fully loaded system with 8 boards it might be=20
a little harder to find an adequate 5V supply.=C2=A0 I thought that 12V=20
regulated down to one or two 5V supplies might make it a little easier.=C2=
=A0=20
This stems from the first 5V supply I tried using.=C2=A0 It was Ok until =
I=20
had the CPU, Memory, MBM, and Bus Monitor all running at the same time.=C2=
=A0=20
Then it was a bit too weak and I had to find something heftier.=C2=A0=20
Actually, it was just the MBM that suffered. Everything else seemed to=20
be Ok.
>
> I have thought about a little clip just to provide board spacing.  even=
 if I add space, a hole, or a tab on future boards, I would like a soluti=
on that is backwards compatible.   that lead me to about the same idea yo=
u mention about just supporting from the back of the board.  I have start=
ed designing a little support that slips over the PCI connector on the ba=
ckplane and comes up the back corners of the board and only extends towar=
ds the component side the thickness of the board so it does not hit the s=
witches on the right hand side or any connectors on the left side.  there=
 would need to be an exception made on the left side for the bus monitor.=
  These would be individual supports so they could be placed as desired a=
nd the bus monitor version put wherever someone likes that board.  I tend=
 to put the CPU board in the front slot so I can get to the ZIF socket ea=
sier and have the bus monitor right behind in the second slot.  Not as im=
pressive to show off because the bus monitor hides everything behind, but=
 most of my visitors' eyes (and all of my family's) just glaze over when =
I start into my electronics projects anyway.
Yes, I'm familiar with that glazed eye phenomenon.=C2=A0 Your idea sounds=
 good.
>
> I think I will pursue that design more... there may be a place that is =
a clear area on all the boards where I can have a little finger come arou=
nd to the component side just so it can keep the board from tipping forwa=
rd.  It wouldn't take much room on the component side.... at first glance=
 and just looking down a row of boards, I think the tiny space just above=
 the CPU ZIF socket would have room for a clip to come around on most if =
not all the boards.  or maybe a clip that can be freely positioned anywhe=
re along the edge... that is probably a better idea but one more part.
>
> I think I can make the clip thin enough around the PCI connector that i=
t will fit the existing four slot backplane, but in the new backplane I w=
ill leave room at the end of each connector for a screw to hold that vers=
ion of the guide down.
>
> I have emailed a dozen or so of the people that I remember purchasing t=
he bubble board and sent them a link to your project.  I wanted to see an=
y response before I email any more.  When I get it running on my boards I=
 would like to do a video on your fantastic project.
Sounds good.=C2=A0 Let me know what you hear.

Thanks,

Denver