"Richard Clark" wrote in message
...
On Sat, 08 Oct 2005 08:05:35 GMT, "Lee"
wrote:

Use the old stand-by of the screwdriver antennas, a screwdriver motor.

Tried that, it has far to much torque even on low volts .... damaged the
gearing on my spare cap :-/

Hi Lee,

One way to control that, at least speed-wise, is to turn the DC
voltage into pulse-width modulated voltage. You are always applying
the same voltage, but you turn it on for a short-to-long time, and off
for a long-to-short time over any interval. You change the speed by
changing these times. This is more properly called Dwell Time.

Yes, i`ve been looking into that and it seems the best way to go, a local
supplier has a panel mount version in stock £15.00 ($16.00??)......so!!.

This offers the prospects of maintaining a constant torque over a
considerable range of speed. I'm not certain by what you mean about
"too much torque," unless you have too much resistance for the gears
to drive....

Not enough resistance, the capacitor comes to the end of its travel but the
torque wants to continue..... hence the damage to my spare capacitor!!!.

Regards.

Lee...G6ZSG......

73's
Richard Clark, KB7QHC