Bringing up a old Powersupply

From: Eric Smith <eric_at_brouhaha.com>
Date: Fri Apr 23 04:29:15 1999

> I've got access to a variable powersupply that will provide
> 0-140 VAC.

I can't help with your general question, but I do have a safety tip. If that
power supply is a Variac or similar device, it is an autotransformer. This
means that it does not have separate primary and secondary windings. So don't
count on it to provide the electrical isolation that you expect from normal
transformers. If you need to probe the line-voltage side of the power supply
with an oscilliscope, for instance, make sure that you also use an isolation
transformer on the input side of the Variac.

I don't want to start yet another discussion on the supposed merits of
floating scopes. An isolation transformer for the UUT is the correct way to
do this. Of course, for this to work you must NOT plug the scope into the
same isolation transformer as the UUT.
Received on Fri Apr 23 1999 - 04:29:15 BST