Hi All:
Michael Ryan asked a question about a meter reader circuit produced by Smith
Kettelwell.  I'm not familiar with that particular one, but I am familiar
with the ones that were produced by science for the blind which was probably
similar to the one Michael asked about.  There were two versions, one was a
relative reading circuit which used a voltage controled oscillator and a
reference pitch to determine relative readings.  The other used a bridge
circuit and a chopper with the balance pot of the bridge having a pointer
and braille dial.  This circuit was used to get more accurate readings.
Both circuits were connected across the meter terminals and used the voltage
drop across the meter. I wrote an article about these circuits in the march
1997 qst.  Let me know if you need more information.

Tony McCloskey, WA3CAO