Re: [N8VEM-S100:999] S-100 backplane request for help

[Paul Birkel <pbi...@gmail.com>]

While John has some great information on his backplane/ps page
(http://s100computers.com/My%20System%20Pages/The%20Box/The%20Box.htm#The_Power_Supply),
one point that is missing is the proper power supply sizing for an
8-slot system.

The IEEE 696:1983 spec is silent on the allowed/anticipated ps-loading
per slot, but it seems reasonable to assume 1 A to maybe 1.5 A average
per slot on the 8V rail, max (most cards hosting a single 1A +5V
regulator, with the occasional dual-regulator configuration like the
dual-IDE card)?  That suggests maybe 12A on the 8V rail, and we might
guess 1-2A max on the +16 and -16V rails (since these aren't used much
at all on modern cards)?

Am I way off-base here?

FWIW, here are what appear to be the most relevant Meanwell supplies
(via Power Factor, as pointed out by John) -- all of which can have
their output voltages adjusted upwards a bit to fit the 8 and 16 volt
bus-targets:

http://www.power-factor-1st.com/g2-series/s-100f.html 7.5V, 0~13.5A  $49.45
http://www.power-factor-1st.com/g2-series/s-150.html  7.5V, 0~20A  $55.45
http://www.power-factor-1st.com/g2-series/s-210.html  7.5V, 0~27A  $70.95
http://www.power-factor-1st.com/g2-series/s-40.html    15V, 0~2.8A  $37.90

The 20A (second line) seems to be the cost-effective sweet-spot "with headroom".

Happy hunting :->.

On Sun, Jul 22, 2012 at 1:55 PM, Andrew Lynch <LYN...@yahoo.com> wrote:
> Hi!  I’ve gotten a request for some help with the S-100 backplane PCB.
> Since it will probably require a PCB respin to fix I would like to gather up
> all the feedback and incorporate them as best I can.  Thanks to Don Caprio
> there are some excellent builder instructions here:
>
> http://n8vem-sbc.pbworks.com/w/page/35158565/Build%20Instructions
>
> Please post photos of your completed working S-100 backplane systems on the
> wiki in the S-100 backplane folder. Actual builder photos are *very* helpful
> for new builders.
>
> http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=S-100%20backplane
>
> There is a new file for S-100 backplane fixes and improvements here:
>
> http://n8vem-sbc.pbworks.com/w/page/55620344/S-100%20backplane%20improvements%20and%20fixes
>
> Please edit with any issues you’ve encountered on how to fix and/or improve
> the S-100 backplane.
>
> The photos that are in the folder at the moment are getting rather dated so
> they should be retired to the archive as to not confuse any new builders.
>
> Thanks and have a nice day!
>
> Andrew Lynch