S-100 power supply voltage ranges

Hi Andrew, Everyone's right--the regulation on the old linear S-100 boxes was none too good--just a big transformer, a bridge rectifier or three, a couple of large caps and that was it. My Integrand box has a transformer you could arc-weld with. On the other hand, the MITS 8800 has an incredibly wimpy supply. I have memories of S100 boards with 7805 TO-220 or LM323 TO-3 regulators leaving nice dark scorch marks on the PCB. That's another reason that I like Multibus better--the regulation is in the PSU, not on the board. If you use one of those 9v SMPSUs and it's a single-output unit, I suspect that you'll be able to tweak the output voltage down by twiddling a pot onboard. At worst, you might need to hook a couple of diodes in series with the output. Speaking as an old timer, a switching supply for S100 seems almost sacrilegious. But you go with what you can get. They're not exactly making big power transformers nowadays--and a switcher allows you to sell to the overseas folks. Best of luck with your project! Will your backplane have active termination? That was always a big plus on some of the better systems. Cheers, Chuck