> The model railroaders use them on small DC motors all the time - instead
> of
> varying the voltage to the motor (which loses you torque) you vary the
> duty
> cycle by switching off the source current with a MOSFET at a high rate
> (~10Khz). This way uou get full torque but less speed.
>
> Come to think of it, that would work REALLY well in this application....
>
> ajr
But you still really need a park position.
I just had the inspiration. Put a small hall effect device inside
the gearbox to sense the crank position. When the crank is not in the park
position turn the motor on. Now all the speed control needs to do is switch
on long enough for a couple of wipes. by varying the delay time from
infinity down to zero the wipers can be switched to operate anywhere from
off to full on. At the end of each on pulse the wipers will find the park
position and turn themselves off. The wper motor will remain extenally stock
except for three additional small wires for the HED and the controller can
be secreted somewhere that won't affect the originallity of the truck and
spoil your chances of a concours trophy.
This archive was generated by hypermail 2b30 : Wed Jun 06 2001 - 11:39:04 EDT