15 Dec
2008
15 Dec
'08
6:29 p.m.
Dave McGuire wrote:
On Dec 15, 2008, at 5:21 PM, Tony Duell wrote:
This what I recall from the brief look I had inside the unit, the relays
were hermetically sealed types for contact reliability.
[NLS's products]
[pardon me for jumping in, but I know a little about the
instrument in question]
It uses relays to switch resistors in and out of what amounts to a And before that, very early digital voltmeters...
How did they work? discrete implementation of a Kelvin bridge, with the
relay
configuration reflected in the displays in much the same way as you
describe the mechanical bridge in the paragraph below. I believe
(but am not sure) that the null detector was a simple comparator
circuit.
The displays are the engraved plate style, edge-lit using
incandescent lamps.
I've been looking for schematics for this instrument for many
years but have not been able to find them.
My plan was to reverse engineer it to produce the schematic,
.. if it hadn't disappeared. I am a tad miffed.