No Spam wrote:
"Dave Plowman (News)" wrote:

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.

No reason why. Even if the meter is not true RMS you can usually get
a reasonable indication of a phase switched dimmer output with any
meter.

Only if there is a load though surely. The current drawn by a DMM will be
many orders of magnitude smaller than that required.

Chris Key