In article ,
David W.E. Roberts wrote:
All worked via a foot switch with a slider (rheostat?) for the uplighter
and an on/off switch for the reading lamp.

Unlikely to be a rheostat - a 150 watt one would get extremely hot. It
will likely be a 'conventional' triac dimmer with a slider pot rather than
the more usual rotary one.

And trying to measure the output of one of these with a meter is pretty
meaningless.

--
*Windows will never cease *

Dave Plowman London SW
To e-mail, change noise into sound.