[R-390] The Penultimate R-390* Ballast Replacement

[Tom Norris]

Simplified Block diagram of the Amazingly Complex Ballast
Replacement Unit (ACBRU) --
http://www.fernblatt.net/R390/superballast.jpg

Could build a simple comparator circuit driving a
stepper motor controller that in turn is coupled
to a motor driven multi-turn pot, but that wouldn't be
much of a challenge.

Better results could be had using a tube based servo
amp with chopper amp a`la T-195 autotune circuit with
selsyns vs newfangled stepper motors. 400 Hz dynamotor
optional.

The Rube Goldberg Award to anyone that samples the
filament current, feeds it to a voltage to freq circuit,
which feeds an AFC circuit similar to the CV-157, complete
with spinning disk to indicate "live" ballast error adjustment.

All of these would require an external chassis, preferably
rack mounted. Why use a simple resistor when you can do
something like this??????

ahem

Time for my medication, or a stiff drink, or both.

Tom NU4G