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litterbox99
December 5th, 2010, 06:05 PM
I'm almost finished with the backplane project, but
I have a few questions first.

For the fuses, I was wondering what the values are?

I figure for the +/- 16VDC 3A should be enough.

For the + 8VDC. This would be set above the current
draw for all the PCB's on the bus. I'll start out at 10A
or so... Or if someone has a recommendation...

My other question is, what is the calibration procedure
or purpose for the 2k pot ?

BTW: The Mouser S100 connectors fit spot on! Everything aligns
fine, the pins are long enough for this thick sturdy PCB & the
mounting holes match up. At 8 bucks or so per connector, not bad.
The only thing is the slot tabs are not gold plated.


I purchased a new digital camera for the girlfriend (an x-mas gift) So
I took it out and played with it. Here's some pic's of the backplane
board and my Imsai.

http://home.mchsi.com/~litterbox99/temp/ims1.jpg

http://home.mchsi.com/~litterbox99/temp/ims2.jpg

http://home.mchsi.com/~litterbox99/temp/ims3.jpg

http://home.mchsi.com/~litterbox99/temp/ims4.jpg

http://home.mchsi.com/~litterbox99/temp/ims5.jpg

FWIW: You may use any/all pic's I post for other purposes.

Thanks !

Todd

NobodyIsHere
December 5th, 2010, 07:08 PM
Hi! Thanks Todd! Your photos look great! Excellent work!

The pot on the S-100 backplane is for active termination of the S-100 pins. Use your VOM to measure a signal pin in the S-100 bus (without any boards installed) and adjust the pot so the voltage is 2.7V. Then the backplane is actively terminated in the middle region between high and low.

Beautiful work! Very nice to see!

Thanks and have a nice day!

Andrew Lynch

douglas_goodall
December 6th, 2010, 07:14 AM
IMS2.JPG shows a vintage computer, and if I am not mistaken, 4-track tapes :-) (now that's vintage).

NobodyIsHere
December 6th, 2010, 08:35 AM
I'm almost finished with the backplane project, but
I have a few questions first.

For the fuses, I was wondering what the values are?

I figure for the +/- 16VDC 3A should be enough.

For the + 8VDC. This would be set above the current
draw for all the PCB's on the bus. I'll start out at 10A
or so... Or if someone has a recommendation...

My other question is, what is the calibration procedure
or purpose for the 2k pot ?



Hi! I would start the fuses at 1A for the +/- 16VDC and 3A for the 8VDC. Depending on what you are using that should be sufficient. If its not enough consider bumping them up a notch.

If you draw much more than that with relatively recent technology then something is wrong. You can adjust to circumstances though. Also using SMPSUs helps since they have built in current limiters.

Thanks and have a nice day!

Andrew Lynch

glitch
December 6th, 2010, 09:16 AM
With my bare minimum S-100 boardset, using vintage hardware, I draw around 4 A from the +8V line. That includes a Cromemco ZPU, Cromemco 4FDC and SC Digital 16K RAM board. The +/- 16V lines are never taxed beyond 250 mA, but the only thing that uses them is the 4FDC's serial port. Sizing the +8V fuse to your power supply's capabilities might be more prudent than basing it on current card consumption.

kyeakel
December 6th, 2010, 10:12 AM
Very nice work litterbox99. Can you identify the connector you used for P1? I haven't found one that is the right pitch.

Thanks,
Kipp

monahan_z
December 6th, 2010, 10:15 AM
Todd I generally allow about 1-1.5A's per card slot. Hopefully your power supply is above that. The -16V is next to nothing, 1A should be fine. I use 3A on the +16,again way over kill I'm sure. It's probably more important to have correct/lower fuses on the extender board because that's the one you will normally be putting new boards into first. I use Jameco resettable fuses (#199938 and 200062) for these.

Nice pictures BTW, I used your picture on the S100Computers site listing the board. Hope that's OK.
John

litterbox99
December 6th, 2010, 03:45 PM
IMS2.JPG shows a vintage computer, and if I am not mistaken, 4-track tapes :-) (now that's vintage).

Yeah that's my 8-track stereo... it's quadraphonic ! You can see a bit of it in the upper left
corner of IMS1.JPG

Here's another pic.

http://home.mchsi.com/~litterbox99/graphics/8track.jpg

litterbox99
December 6th, 2010, 03:52 PM
Very nice work litterbox99. Can you identify the connector you used for P1? I haven't found one that is the right pitch.

Thanks,
Kipp


If you go here;

http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder&param=S-100%20backplane

Theres a few files with the part numbers you need.

mark66j
December 6th, 2010, 05:19 PM
Yeah that's my 8-track stereo... it's quadraphonic !

Sorry to prolong the off-topic stuff, but that stereo must be from the 1970s. The design of the front panel is definitely classic. You really should get a leisure suit to wear when listening, however.

NobodyIsHere
December 6th, 2010, 05:26 PM
I don't care if it is off topic... 8 track players are awesome! Check out those classic hits of the 1970's and 1980's

Here is what I can see from the photo:

Head East
The Worst of Jefferson Airplane
Atlanta Rhythm Section
Chicago
Jim Croce
ELO Out of the Blue
Flock of Seagulls (!!) (oh man, I wish I still had hair!)
Eddie Money

Seriously dude, we need a close up of your 8 track collection!

I'll bet there are a couple Abba and Donna Summer's tapes hiding in there someplace!

:-)

Thanks and have a nice day!

Andrew Lynch

PS, did you get one of the S-100 Z80 CPU boards (sorry to be the buzzkill). Does it work? Would you post a photo? John got his working at 10 MHz.

PPS, just take photos of your whole workshop! This is the most entertaining thread in weeks!

litterbox99
December 6th, 2010, 07:11 PM
You guy's have a good eye for music...

First off, thanks for the nice comments !

I do like my 8-tracks. With all the technology, it's nice to step back to an
analog word, relax and play some tunes and just enjoy. If you have the time,
just check out my world... This web page is about a year old & pre S100 obsession.

http://home.mchsi.com/~litterbox99/pikx.html

I have some time off at the end of the year, I plan to take new pic's
of what I call my "lab", for gods sake I wont call it a man cave ;-)

MikeS
December 6th, 2010, 08:00 PM
Yeah, I've also got a hundred or so 8-track carts and several players and recorders (no true quadraphonics though); they are fun, although you do have to replace the odd pressure pad when the foam rots, and splice the odd tape when the adhesive on the splicing/sensing tape dries out...

@ Douglas: 4 track cartridges were quite different.

NobodyIsHere
December 7th, 2010, 03:31 AM
Hi! THANK YOU for the photos! They made my day and are wonderful! They are a lot of fun but also are a great way to help the N8VEM project. I talk post and talk forever but your photos of bringing a vintage computer back to life with the S100computers.com and N8VEM S100 boards are *much* more effective. Please keep posting!

Thanks and have a nice day!

Andrew Lynch