"Phil Allison" wrote in message
...

"dave"

A Dim Bulb current limiter will protect better than a Variac. fyi.

http://www.kendrick-amplifiers.com/m...tegory_Code=04


** A Variac alone provides no protection.

But the method I outlined is vastly superior to the old light bulb trick.

Variac + true rms current meter + fuse (which can be a fast blow type).

There are far too many anomalies when a series lamp is fitted to the AC
supply.


... Phil


Agreed. The dim bulb limiter is a bit of a catch-all largely designed for
production testing by people no necessarily skilled in electronics. A variac
used in the way you suggested, and the way that I too use mine, is just as
effective at avoiding burnups in a fuse-blower, whilst actually providing a
greater level of information about where to be looking for the problem. The
trick is that like an ESR meter, a degree of skill is required to use the
variac correctly (for this type of fault finding) and to interpret the
results obtained ...

Arfa