"Stan" wrote in message
...
| "NSM" wrote: "Robert Wolcott"
wrote:
....
| }What voltage batteries? I'd be inclined to look at chopper type DC
control
| }systems. GE published some in the 60's that used a couple of SCRs to
control
| }the speed.
|
| SCRs??? In a DC circuit??? How could a circuit drive the voltage to
| zero in order to get the SCRs to stop conducting? Or has someone invented
| an AC battery while I was asleep?

Nope! IIRC, you use a timing circuit to fire one SCR to turn battery current
on. Then, to turn it off, you fire a second one in parallel with the first
but into a capacitor. This shunts out the first which turns off, then the
second one turns off when the cap is charged. Track down an SCR manual from
GE in the 60's or 70's and you'll see the circuit. I believe it was designed
for electric golf carts.

NM