[AMPS] How to control a vacuum C ??

[Verner Topsøe-Jensen OZ5TG]

I am trying to build a controlcircuit for a major PA with an YC156.
I am using a pair of Jennings 10-1000PF motordriven capacitors.

Problem :
The integrated DC-motors requires 18volt to work reliably, but the
end-to-endtravel takes only about 3 seconds i.e. 330PF/sec.
The controlcircuit has a delay at about 25mSec i.e. the cap. stops
8 - 10 PF off the wanted value. No problem on 160, but on 10, it
is a matter of success or failure.

The controlcircuit using variable resistors, cannot, even with a very little
hysteresis, stop the motors without overshoot. 

I have tried to chop the DC for the motors. That was an improvement,
but far from enough.

Any ideas about how to slow down the RPM and maintain the torque ?

I checked the Jennings URL, but they do not have any information about 
how to do.


Any help, any idea is welcome.


OZ5TG, Verner


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