[volt-nuts] 3420B chopper drive problem

[Dr. Frank]

Another probable error in the manual, on page 5-8 (80), diagram, which 
shows the monitoring of the neon currents:

That diagram is ok for the A-version, as both neon currents are measured 
with the same polarity in its oscillator circuit.

The B-version anyhow should look different, as the currents should be of 
different polarity, so a positive pulse with about +150mV, and a 
negative pulse with -75mV (or vice versa, depending on the polarity of 
the diodes), always a signal pause at 0V.

One neon current is monitored over 51 Ohm, the other one over two 51Ohm 
reistors in series, therefore these different amplitudes.

Frank