On Sat, 1 Dec 2007 22:11:20 -0500, "Buck Frobisher"
wrote:

Saw this at an antique shop today, couldn't for the life of me figure out
what it is. The label says Honeywell "Potentiometer", but it sure seems to
look like more than that!

"Standard Cell" as mentioned on the yellow tag in one of the photos is one
of those calibrated battery cells that was talked about on RAR+P a while
back, right?

Just curious if anyone can tell me something about it.


Just a precision potentiometer to adjust the output voltage to an
accurately known value, and allow comparison with an external (low)
voltage that you need to accurately measure.
Usually there is a battery votage source, and it is compared and
standardised against the Standard cell, and adjusted so that the
potentiometer settings read directly in volts. Then this can be used
to compare with an external unknown supply by adjusting the
potentiometer setting till the galvanometer reading is zero. The
unknown voltage, and the potentiometer then are the same voltage, and
you read the value directly off the scale.
So it is basically used as an accurate voltmeter which has its own
calibrator, and is high input impedance at the setting where the
measurement is made. Usually used in the millivolts range, although
High voltage units were also used.

Peter Dettmann