My return to Classic Cmp - San Diego, software archive, etc.
ard at p850ug1.demon.co.uk
Tue Dec 16 13:04:24 CST 2008
> In the early days of my youth (pre computer), I worked as an
> instrumentation technician. Many chart recorders, such as L&N
> Speedomax, used a "slidewire" that resembled a single-turn wirewound
> potentiometer. But the Honeywell Brown Electronik recorders used a
> multi-turn helical pot about the size of a coffee mug. I never
> understood why they were referred to as "slidewires" and not
> "helipots". It was not uncommon for the line operators to steal the
> silver bead used as a contact in those.
I have the mechanism from an old chart recorder, I beleve a Honeywell, but
modified by Pye Unicam, which has 2 feedback pots. One is the normal
linear slidewire mounted across the chassis (the slider being on the pen
carriage. The other is an accurate logarithmic pot driven by a pulley on
the drive cable that links the motor to the pen carriage. I also have a
little box of electronics containing a cathode followe buffer and a relay
to switch between the 2 slidewires. The insturment, of course, could
either have a linear or logirithmic pen movement.
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