IMSAI Score update/Spare BYTEs/Got an Altair too

[Dwight K. Elvey]

>From: ard at p850ug1.demon.co.uk
>
>> By the way, the power supply, so far, has tested fine. I'm going to look
>> for any ripple with the scope later today. I've never done that test --
>> should I DC or AC couple the scope for that test?
>
>AC coupled. That's really what AC coupling is for -- you want to ignore 
>the steady DC level (of several volts) and look at the (hopefully) much 
>smaller AC ripple on top of it. To do that you need to turn up the Y 
>sensitivity on your 'scope, and unless you have a differential comparator 
>input or something, you won't be able to keep the trace on-screen with DC 
>coupling. 
>
>Don't worry too much about ripple on an S100 supply. The S100 supply is 
>not regulated -- the regulators are on each of the boards (the 8V input 
>is designed to be regulated down to 5V, etc). The regulators should take 
>care of small amounts of ripple on the backplane supply lines.
>
>-tony
>

Hi
 For this particular test, using DC coupled is probably
best. As Dave mentions, you just don't want the voltage
on the unregulated 8 volt line to drop below 7 volts.
It can tolerate a relatively large ripple.
Dwight