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NobodyIsHere
April 7th, 2009, 02:14 PM
Hi All! For some time now I've been working on a side project to make an S-100 backplane. After some feedback, I've got a design for a small 6" x 8" backplane of 6 slots with active termination. I will post an updated ZIP file with the specifics if you'd like to see it. You'll need to supply your own power supply, S-100 boards, and parts.

I am considering doing a small PCB manufacturing run in the relatively near future to assess this prototype. What I am looking for is a small group of experienced S-100 builders who'd like to purchase one of these boards (at cost, PCB only, plus shipping) to help with building it and checking it out. I am trying to keep the costs low but the PCB will be in the $30-$40 range.

If you are interested please contact me by PM or post here.

Thanks and have a nice day!

Andrew Lynch

MikeS
April 7th, 2009, 02:43 PM
I know you guys have been shopping around; what's the best price you found for the S100 connectors?

NobodyIsHere
April 7th, 2009, 03:31 PM
Hi Mike, if you are willing to use wire wrap connectors and solder them in (heresy, I know) you can find them for $3 each on eBay. I've seen various prices around but from Digikey I recall the prices were like $7-$9 each for the proper connector with solder tabs.

I am specifying a 40 mil drill hole (0.04") for the S-100 connector. The PCB will be double thick for rigidity (1/8" or 3.2mm) and use double weight copper traces. The regular signal traces will be 17 mil width and power traces will be 51 mil width. The minimum clearance will be 11 mils. I will place copper pour fill zones for heat dissipation and grounding.

As soon as the trace router is done I'll post some PDFs of the schematic and PCB layout. The design is pretty neat as there are *no* vias other than the PTHs for devices.

Thanks and have a nice day!

Andrew Lynch

PS, not to discourage people but if you are considering this project you should be aware this is a "experimental untested prototype" release intended for hobbyists fairly experienced in electronics to help verify the design. It is *not* a kit and probably will contain errors requiring fixes before a general release. In other words, be prepared to use your own oscilloscope, VOM, soldering iron, S-100 boards, power supply, etc.

NobodyIsHere
April 8th, 2009, 02:28 PM
Hi! Here is the preliminary design for the schematic and the PCB layout.

http://n8vem-sbc.pbwiki.com/browse/#view=ViewFolder&param=ECB%20to%20S-100%20Bus%20Bridge

Comments, questions, are welcome. Thanks and have a nice day!

Andrew Lynch

PacMan
April 9th, 2009, 05:59 AM
Looks good Andrew, I look forward to reading about your progress.

/P

NobodyIsHere
April 15th, 2009, 04:49 AM
Hi! Based on some feedback I received on the N8VEM mailing list, I have totally redesigned the S-100 backplane. It is now a 6 slot unit with active termination. It includes mounting holes for each slot and additional chassis mounting holes for stress relief. Nearly all the traces have been migrated to the component side of the PCB and the copper side is almost entirely a ground plane for improved signal performance. There are no vias at all on the PCB and only the minimum PTHs for the components.

The PCB will be double thick for rigidity and durability (3.2mm or 0.125") and use double weight copper (2oz) for traces. Regular signal traces will be 17 mil wide and power traces will be triple width (51 mil) for low impedance rails. minimum clearance is 11 mils and normal round PTH pads used throughout. For now, the builder will have supply their own power supplies.

As soon as this unit completes its trace routing, I will update the files on the N8VEM wiki and request further comments. My plan is to make a small initial run of PCBs for advanced builders with two purposes in mind; find out if there are any major problems with the design and also to gauge the degree of interest in an amateur S-100 backplane.

Obviously, there are limits to making a prototype of this design so there is some degree of risk for the advance builders. The way to mitigate the risk is to do as much review as possible. I am making a good faith effort to make this as defect free as possible but as an amateur project there are no guarantees. Most likely any problems discovered can be resolved with the usual cuts and jumpers or other common work arounds.

Costs will be an issue with this project since the PCB is now about 7.5" on each side and over 50 square inches of area. That means the PCBs will be in the $30 to $40 range at the outset. Most of the components are common and relatively inexpensive but the S-100 connectors themselves are not easily obtained and can be expensive when you do find them.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
April 17th, 2009, 08:02 AM
Hi! I updated the zip file with the information on the N8VEM wiki. If you have any comments or suggestions please I'd appreciate hearing them. I'd like to go to manufacturing soon with this design so if anyone is interested in participating in the trial run please let me know.

Thanks and have a nice day!

Andrew Lynch

PS, I swapped the copper and component planes so now almost all of the traces are on the copper side and the large copper pour/ground plane in on the component side.

PacMan
April 17th, 2009, 08:09 AM
Andrew,
I'd be really interested in buying one for my Mishmash computer. Let me know when you are getting ready to produce them. I will look over the plots again and let you know if I find anything dubious.

/Pontus

NobodyIsHere
April 17th, 2009, 08:46 AM
Andrew,
I'd be really interested in buying one for my Mishmash computer. Let me know when you are getting ready to produce them. I will look over the plots again and let you know if I find anything dubious.

/Pontus

Hi! Thanks! Yes, that is the ideal application for this S-100 backplane. My intent is for this to be a bench tool for home brew computing hobbyists to repair their S-100 boards and/or prototype new boards. It could be used to base a new home brew S-100 system but there is no case or chassis for it at the moment.

My recommendation is to test the backplane thoroughly before using it with boards. Also don't to use irreplaceable boards during the initial build until we're sure its working properly. You may consider using one of your S-100 prototype boards and rig a test board first.

If this backplane project is successful enough that it works and there is enough interest to at least cover my costs of its manufacturing run, I would like to take on some of the other difficult S-100 related hobbyist issues like the lack of readily available compatible linear power supplies, etc.

As you pointed out earlier, you can use SMPSUs but I've found them to be rather expensive solution ($100-$150 or so) since it appears, or at least I cannot find, a suitable SMPSU unit with three rails of 7.5 to 9 VDC, 15 to 18 VDC, and -18 to -15 VDC. That means multiple units are required and that gets expensive unless one wants to modify an SMPSU.

I investigated using a mixture of repurposed laptop and printer PS units but that is a nasty kludge and I don't think they have sufficient capacity for even a small S-100 system. As you said earlier, quality power supply is crucial to a reliable system. What would be a ideal would be a DC/DC converter to allow an ATX supply to be used but so far I've found nothing with useful current capacity with a reasonable price.

It'd be great if I was wrong but the really big problem with home brew S-100 systems is the power supply.

Thanks and have a nice day!

Andrew Lynch

PacMan
April 18th, 2009, 06:45 AM
Andrew,
How about implementing your own switched power supply on board the motherboard. There at least a million different good switched power supply controllers available from a number of vendors. This way a user could use one of the inexpensive notebook power supplies you mentioned earlier.

Pontus

NobodyIsHere
April 18th, 2009, 05:00 PM
Andrew,
How about implementing your own switched power supply on board the motherboard. There at least a million different good switched power supply controllers available from a number of vendors. This way a user could use one of the inexpensive notebook power supplies you mentioned earlier.

Pontus

Hi! I considered designing a custom SMPSU but to be honest I really don't have the experience to pull off one of those. While I am OK with designing a linear power supply as it is simple enough that I can probably get something to work "well enough." designing a SMPSU, at least a good one, is a really advanced skill.

My plan is to build the linear PS on a separate board and if it proves out possibly release a later design with an integrated backplane and linear power supply.

Thanks and have a nice day!

Andrew Lynch

Dr_Acula
April 19th, 2009, 06:55 AM
I'm totally hooked on the LM2575. $2.45 at futurlec. Then you just need a few capacitors, a 1N5819 diode and a 330uH inductor that is under 1 ohm resistance. I got a whole pile of those for $2 each. I'm now dropping them onto boards instead of the 7805. They work exactly the same, except they only mildly get warm even when running at 800mA. When you factor in the cost of a heatsink for a 7805, the cost is about the same for a switcher. They run up to 1A.

You can have one for each voltage level. I don't know about the current levels - but an entire N8VEM with cmos components is only 65mA. But I guess if a board was LS (or TTL...). Or maybe seperate supplies for each board (if each one comes in under 1A). What are each of the rails driving? There are mods around to PC power supplies to tweak the output volts.

NobodyIsHere
April 20th, 2009, 04:45 AM
Hi! The S-100 power supplies are really an odd mix and are probably almost unique in microcomputers. They are really comprised of two parts external and internal. The external power supply provides +8VDC, +18VDC, and -18VDC *unregulated* to the S-100 connector pins. Then the cards internal power supply section uses whatever local regulators it needs to create its rails as needed. That's why you see commonly see on S-100 boards 7805, 7812, 7905, 7912, zener diode circuits, and the like that you don't often see on more recent systems. It also makes building an S-100 power supply a real PITA.

With recent systems using supply voltages less than +3.3VDC I suppose you could say the two part power supply approach has made a come back. Many modern CPUs and memory systems use low voltages that the motherboard creates locally.

I am cobbling a temporary S-100 power supply together based on a mixture of low cost SMPSUs and repurposed laptop power supplies. It will probably work and not be too expensive but its no substitute for the real thing.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
April 23rd, 2009, 04:09 AM
Hi! I am expecting the first round of home brew S-100 backplanes to arrive in mid-May or so. They'll be available for $32 each plus shipping which is typically $2 in the US and $5 overseas. My intent is to get them to some S-100 enthusiast/hobbyists as low cost as possible while not taking a big loss myself. The $32 price is literally "at cost" -- the actual cost of the boards divided by the number of units.

These are prototype boards and only a small quantity will be available. The goal is to have these first generation boards get a thorough shake down to determine if they work well enough and there is sufficient interest to do a second generation.

Hopefully the initial round builders and testers can see this project as an investment and worthwhile. It is a prototype board so there is some risk involved. However, how many new S-100 backplanes can you buy anywhere these days at any price? Especially a low cost unit where you can influence the design. Vector was the last S-100 backplane manufacturer I know of. The IMSAI II team did release some units I think. I don't know if those actually made it out of testing though.

Thanks and have a nice day!

Andrew Lynch

PacMan
April 23rd, 2009, 04:43 AM
Andrew,
I'm on for one. I have a few connectors left from my last order from Digikey which should be okey. By the way, what pitch between the connector rows are you using ?

/Pontus

NobodyIsHere
April 23rd, 2009, 07:23 AM
Andrew,
I'm on for one. I have a few connectors left from my last order from Digikey which should be okey. By the way, what pitch between the connector rows are you using ?

/Pontus

Hi! I am using what I think are standard S-100 connectors. They are 0.125" (3.18mm) pitch connectors and 0.250" (6.36mm) between the two rows.

What part number did you order from Digikey so I can check the datasheet? Most S-100 backplanes that I know of use the 0.125"/0.250" combination. I suppose there could be variations as there are a *lot* of S-100 variants.

Thanks and have a nice day!

Andrew Lynch

PacMan
April 23rd, 2009, 02:27 PM
Ouch, just checked my connectors and they are the Altair type who are 3.18mms between the rows. Anyway, you should go for the 0.125"/0.250" combo since those connectors are much less expensive than the Sullins connectors. I think mine were something like 16 bucks a piece and I had to get 20 of them. They have the 0.125"/0.250" on digikey at 8 bucks a piece and that's not too bad.

/Pontus

NobodyIsHere
April 28th, 2009, 05:00 AM
Hi! Thanks for the info on the S-100 connectors. I had assumed that since all of my S-100 related parts used the 0.125"/0.250" parts those were the way to go. I was not aware of the Altair parts until you pointed those out.

You are right though as the 0.250" parts are significantly less expensive. The good news is both S-100 connector styles seem to be in production and readily available. Not cheap but available. I see at Mouser you can get the parts for $5 each and I've seen even better deals on eBay.

Last night I received an email from the PCB manufacturer so I should be receiving the boards in the next few days. Also I ordered all the parts from Digikey so I can build a prototype. My 8VDC PS arrived but it requires some funky connectors :-( I may just solder to bypass them.

So this project is moving if glacially slow. More as it develops.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 1st, 2009, 07:42 AM
Hi! I noticed a FedEx notice on my door yesterday when I got home so I think the S-100 backplanes will be delivered today unless its something else they are delivering. Also my package from Digikey arrived so I have most but not all of my parts now. Stand by for news!

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 1st, 2009, 01:46 PM
Hi! The S-100 backplane PCBs have arrived. Please contact me if interested getting one. Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 3rd, 2009, 01:00 PM
Hi! I've partially built one of the unit for testing. I've gone as far as I can go but some parts are on back order. I may try to pick up some locally next weekend. What I am missing are the power connectors (0.200" spaced headers male and female). My plan is to finish assembly and test the active terminator section before installing the S-100 connectors.

Two of the eight units for initial testing have already been spoken for. If you would like your own S-100 backplane please contact me. The PCBs are $32 each plus $2 shipping in the US. Shipping overseas is typically $5 per PCB.

Some people have been concerned about availability of the S-100 connectors but they are plentiful and relatively cheap. At Mouser you can get EDAC parts which should work for $5 each. (http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMv12%252brFPZJrWeHn hmJkGRvZEMipDd52S5o%3d) You can also substitute wire wrap connectors which sometimes can be found on eBay for $3 each.

There are photos at the wiki here (http://n8vem-sbc.pbworks.com/browse/#view=ViewFolder&param=S100)

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 7th, 2009, 06:13 PM
Hi! Well today has been a great day for the N8VEM S-100 backplane project! My parts arrived and I was able to finish construction except for the bus connectors. In addition, I finished making the power supplies and hooked everything up... No Magic Smoke Released! Yahoo! Also the active terminator circuit appears to be working. I can adjust the trimmer pot to get exactly 2.7v on the bus signal lines which is really great! All the proper voltages are appearing on the bus at the supply rails so that is cool too.

My kludged power supply is 8VDC @10A regulated, +15 @6A regulated, and -15VDC @6A regulated. Its a bit on the light side for S-100 requirements but there are only 6 slots so it should be OK at least for more testing. The good news is that I made the power supply for less than $40 including shipping.

I uploaded three new pictures of the updated partial assembly to the N8VEM wiki. The next step is to get a power strip and also mount all the pieces on a piece of plywood for more testing. Then install the bus connectors and start testing with S-100 boards. This is going to be fun!

http://n8vem-sbc.pbworks.com/browse/#view=ViewFolder&param=S100

Any comments, suggestions, questions appreciated! Thanks and have a nice day!

Andrew Lynch

billdeg
May 10th, 2009, 05:51 AM
Nice web site. If you were to compare this system to something, would it be the Morrow Wunderbus or something like that?

billdeg
May 10th, 2009, 05:57 AM
Actually to answer my own question, not really. The Wunderbus has 18 slots, probably needs a heftier power supply.

NobodyIsHere
May 10th, 2009, 11:08 AM
Hi Bill! Well, its kind of hard to say. The design is an amalgam of various ideas and designs floating about. Clearly the active terminator is similar to the early Godbout designs. I used a home brew S-100 chassis, motherboard, with active terminator as my reference. Terry and Erik sold me the home brew S-100 chassis a couple of years ago and I got familiar with it during its repair. Obviously the original designer was a big fan of the Godbout stuff!

I am also working on an S-100 board "blank" to capture the basic outline of the card. I looked into IEEE-696 and also compared several S-100 boards and prototype boards but there is a *lot* of variation between units. Its a wonder anything works! I'll upload a PDF of what I have so far.

Of the eight S-100 backplane boards for the initial round of testing, I have shipped four. I still have four left if anyone would like to join me in testing this unit. I have mine basically assembled except I've only installed two bus connectors while in testing. I am finding some little things to make better in future versions but no show stoppers. KiCAD gave me some troubles in keeping some nets straight but nothing fatal.

I'd be glad to help anyone with S-100 power supply considerations. The kludged unit I rigged up is working OK so far.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 10th, 2009, 07:39 PM
Hi! Well, I've been working on making the male card edge connector to fit the S-100 female card edge connector on the N8VEM S-100 backplane. I've been puttering with it for a while. Its along story but I started with something simple and ended up with a S-100 prototype board design. Please check it out and as always your comments, questions, and suggestions are welcome!

If there is sufficient interest I may go with a small PCB manufacturing production run. Please contact me offline. I don't know what the price per PCB would be but I'd guess it'd be in the $25 each neighborhood maybe less if there is enough interest.

BTW, I have basically finished my S-100 backplane assembly and it seems to work OK with the kludged power supply. I still have 4 of the 8 test boards and my confidence in this working has increased dramatically. If you'd like help making a power supply I can help with that too. My next project was going to be a linear power supply PCB but I got side tracked on this prototype board project.

Thanks and have a nice day!

Andrew Lynch

PS here is the URL http://n8vem-sbc.pbworks.com/browse/#view=ViewFolder&param=S100

Its the board named "Printing S100_Blank-full-brd.pdf"

NobodyIsHere
May 11th, 2009, 04:46 AM
Hi! Here are some notes I've accumulated regarding availability of S-100 bus connectors. Prices range considerably and although I have done my best to make sure these are accurate be sure to double check so you get what you really need/want!

http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMv12%252brFPZJrWeHn hmJkGRvZEMipDd52S5o%3d

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=EDC346102-ND

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=S3288-ND

http://www.newark.com/itw-mcmurdo/346-100-526-802/edge-connector-50way/dp/08WX2950

http://jdr.com/interact/item.asp?itemno=gr-44p-ww

http://www.electronicsurplus.com/dictionary/cat1956.htm

http://catalog.tycoelectronics.com/catalog/bin/TE.Connect?C=20858&M=FEAT&P=115288,137910,11808,10087&U=&BML=&LG=1

http://avnetexpress.avnet.com/store/em/EMController?langId=-1&storeId=500201&catalogId=500201&action=products&Nn=25&N=4294965929+4294738841+100336+4294963223

http://avnetexpress.avnet.com/store/em/EMController?langId=-1&storeId=500201&catalogId=500201&action=products&inStock=&rohs=&proto=&cutTape=&topSellers=&Nn=25&cat=1&N=4294966376+100336+4294950724+4294855990+42949632 23

http://www.vikcon.com/images/.125contactcenters.pdf

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
May 13th, 2009, 04:46 AM
Hi! Of the 8 units for initial testing, I have shipped 4 to testers and 1 is committed. I still have 3 remaining units so if anyone would like to build their own home brew S-100 system with this backplane this is great opportunity to start. A lot of the testing is basically done and the backplane is checking out fine. I think the S-100 backplane would make a good bench unit for fixing, testing, repairing, and prototyping your own S-100 boards as well.

Please contact me if interested. Thanks!

Andrew Lynch

NobodyIsHere
July 14th, 2010, 04:24 AM
Hi! Its been a while since I've done anything with the S-100 backplane. There are several builders waiting for another PCB run and a lot of feedback on how to improve the board. I am doing a PCB respin at the moment and addressing several issues.

The S-100 backplane PCB will have active termination like the first one and retain the same form factor. It has a power supply connector for +15V, +8V, and -15V. Those voltages can vary somewhat since the boards use local voltage regulators. I am using scrap laptop and printer "power bricks" on mine but you can use anything you'd like.

The new S-100 backplane will have 8 slots instead of 6 and the spacing between slots is reduced to the IEEE-696 standard of 0.75". I am also adding power LEDs for the three power inputs. There is a reset button and 2 pin connector for external reset including a jumper for CPU reset and/or external clear (peripheral reset).

The S-100 backplane retains its mounting holes and as many traces as possible will be on the component side. The copper side will be all ground plane to improve EMI performance. The PCB will be double thick (0.125") and use double weight (2oz) copper. All signal traces are 17 mils wide and the power related traces are 51 mil. Ground pins will have thermal relief pads to ease soldering issues.

I don't have a price or an ETA yet but this board will be in the queue for another PCB manufacturing order. New boards have higher priority and since there are several coming out soon they will probably be dominating the PCB manufacturing orders for a while. However when I get a chance the plan is to make another run of the S-100 backplane.

If anyone has ideas or suggestions regarding the S-100 backplane respin now would be a good time to discuss. However, I am not interested in making this backplane a 12, 18, 22, or even larger multi slot unit due to cost issues involved. Also one of the main purposes of this board is to be small, cheap, and relatively portable for benchtop work in repairing and restoring vintage S-100 bus systems. 8 slots is sufficient for build and test of small systems and a few vintage boards. The S-100 backplane will work as a main system backplane but that is not my primary goal.

One thing I am curious about is if there were ever any standards for S-100 backplane mounting holes. There doesn't seem to be any and placement varies quite a bit among the S-100 backplanes I've seen.

Thanks and have a nice day!

Andrew Lynch

granzeier
July 26th, 2010, 07:39 PM
Hi! I've partially built one of the unit for testing. I've gone as far as I can go but some parts are on back order. I may try to pick up some locally next weekend. What I am missing are the power connectors (0.200" spaced headers male and female). My plan is to finish assembly and test the active terminator section before installing the S-100 connectors.

Two of the eight units for initial testing have already been spoken for. If you would like your own S-100 backplane please contact me. The PCBs are $32 each plus $2 shipping in the US. Shipping overseas is typically $5 per PCB.

Some people have been concerned about availability of the S-100 connectors but they are plentiful and relatively cheap. At Mouser you can get EDAC parts which should work for $5 each. (http://mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMv12%252brFPZJrWeHn hmJkGRvZEMipDd52S5o%3d) You can also substitute wire wrap connectors which sometimes can be found on eBay for $3 each.

There are photos at the wiki here (http://n8vem-sbc.pbworks.com/browse/#view=ViewFolder&param=S100)

Thanks and have a nice day!

Andrew Lynch

Andrew,

Could you give some more info on your kludged power supply. I have several notebook and printer power supplies and would like to (finally) put together an S-100 system. I have a Cromemco 21-slot motherboard with cage and card guides (in great shape - it is available for trade for a smaller system) but would hook up a kludged power supply to it to test out some of my cards and throw together a simple system (start with my Cromemco SCC and then add a 64K memory board and then maybe one/some of my other boards.

Thanks,

Art

NobodyIsHere
July 27th, 2010, 03:41 AM
Hi! You can use any sort of SMPSU although for small loads you can use repurposed laptop and printer power bricks. Obviously only use scrap units. What you need is at least one rather beefy brick that can generate 7.5V-10V for the 8V rail (pins 1 & 51). The closer to 7.5V the better but not less than since the 7805 voltage regulators (or equivalent) have to have some "headroom" to generate 5V. However any voltage above 7.5V is wasted heat so 7.5V is ideal.

Similarily you'll need a pair of 14.5V-18V power bricks for the +15V and -15V rails. The +15V rail is (pin 2) obvious but the -15V rail (pin 52) is powered by a two conductor power brick I just flipped the positive lead and ground. This trick only works with isolated ground power bricks (there are only two lines coming out of the brick and neither is electrically common with the ground input power to the brick).

My only caution is that screwing around with repurposed power supplies can be extremely hazardous so please *BE CAREFUL* If you don't know what you are doing you can hurt or kill yourself quite easily. It may be easier to just get some inexpensive Meanwell SMPSUs off of eBay. The real trick here is to remove any boards from the chassis and when POWERED DOWN, connect each supply to the appropriate rails and measure the voltage available at the bus pins. The power down and connect another, measure, and repeat until it is all connected. Another good idea is to rig up an S-100 prototyping board with some voltage regulators and LEDs with resistors to make a bus power check tool. If the VRs or LEDs don't come on (or catch on fire) obviously something isn't right.

Seriously, be careful and you can reuse old scrap power supplies. This is certainly practical and can save a lot of money *and* find a use for some old junk headed to the e-waste dumping grounds.

Thanks and have a nice day!

Andrew Lynch

granzeier
July 27th, 2010, 04:22 PM
Andrew,

Ok, got that - been working with electronics for over 40 years, so if I screw up, I only get what I deserve (I do give electricity respect, not always enough, but...).

My question here is: what do you use to get the output of the p/s (most of mine are a bit above 8 VDC) down to the 7.5? I know of a lot of ways (regulators, resistor dividers, etc), but what is the way that you used to get them down to the required voltages - or did you just find the closest and let it run a bit hot?

Thanks again,

Art

NobodyIsHere
July 27th, 2010, 07:58 PM
Hi! OK good, I worry that sometimes giving advice might get a newbie killed so I tend to be overly cautious.

I just dug through the pile until I found a 7.5V power brick. There was one for a laptop of some type or maybe an old printer. I used a couple of the 15V Dell laptop power bricks. An 8V power brick would work fine. I would not exceed 10V though as that will run the 7805's too hot. Anything between 7.5V-10V would be fine. Many of the old S-100 chassis ran the 8V rail at 10V so most boards are ready for it.

You can also modify old AT power supplies. There are instructions on how to do it if you search. Basically it is replacing one of the feedback resistors with a potentiometer. Frankly, I haven't bothered since there are so many of these old orphan power bricks laying around looking for a use. As long as you aren't pulling huge current from them they'll work just fine. I wouldn't power a rack full of 8K SRAM boards for instance...

Thanks and have a nice day!

Andrew Lynch

karl benn
August 2nd, 2010, 09:43 PM
hello,

I am considering doing a small PCB manufacturing run in the relatively near future to assess this prototype. What I am looking for is a small group of experienced S-100 builders who'd like to purchase one of these boards (at cost, PCB only, plus shipping) to help with building it and checking it out. I am trying to keep the costs low but the PCB will be in the $30-$40 range.

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NobodyIsHere
August 3rd, 2010, 03:54 AM
Hi Karl,
Yes, the S-100 backplane PCB did go through as planned. Indeed it was popular enough that I will be making another PCB manufacturing run in the near future. This will be a respin of the PCB based on feedback I received from the first batch. The changes are simple but many builders requested them. As I remember they are:

Increase slots from 6 to 8
make slot spacing IEEE-696 compatible (0.75" center to center, was 1.0")
added reset switch and jumper
added power LEDs for +8V, +15V, and -15V rails
added inline fuses

All the other features are still intact like the active termination, power interface, etc.

I am not sure when the PCB manufacturing run will happen but hopefully soon. It has been a while and I think it would be helpful to have another batch for the builders to use.

Thanks and have a nice day!

Andrew Lynch

NobodyIsHere
September 23rd, 2010, 05:48 PM
Hi! The good news is I did finally order a new batch of S-100 backplane PCBs. They are here but going fast to their new builders. I sent along most already but there are a few left if anyone is interested. They are $20 each plus $3 shipping in the US and $6 elsewhere. If these manage to run out I will order some more but probably after this batch settles in so I can get feedback.

There are several of the earlier S-100 boards that need reorder/respins so they are probably next in the queue. After looking at the waiting list, it looks like its the highly controversial S-100 Parallel ASCII keyboard boards turn next. That ought to be interesting and it needs a respin in a big way. It is a cool board but has several annoying bugs. There are no show stoppers and it works amazingly well. It's not for everyone though!

Thanks and have a nice day!

Andrew Lynch

litterbox99
October 20th, 2010, 06:15 PM
Project Status:

Are these PCB's available ?

Where may I find the current doc's ?

I've read this thread and it was last mentioned that the
slot count is currently eight, but the pic's & pdf's on wiki are
of the original six slot design. I have a case in mind, but with
limited footprint, the PCB size important.

Any updated info would be great !

Todd

NobodyIsHere
October 21st, 2010, 03:13 AM
Hi! Thanks! Yes, there are a couple of PCBs still available. There is a folder on the N8VEM wiki called "S-100 backplane" with the latest schematics, PCB layout, and parts list. It is an eight slot backplane with active termination. There are a variety of other useful things like reset switches, power connectors, inline fuses, power indicator LEDs, etc.

Thanks and have a nice day!

Andrew Lynch