Michael A. Terrell wrote:
Jamie wrote:
Michael A. Terrell wrote:
Claude Desjardins wrote:
wrote:
Just take it apart, I'm pretty sure it's just a "potentiometer"
(variable resistor) so it would only have 3 leads, one from the external
wire to the pot., one from the pot to the motor, and one from the other
external wire to the other lead of the motor.
Cut things off, plug the external leads directly to the motor.
Unfortuantely it doesn't seem that simple. The speed control has what
looks like a some kind of semiconductor/IC (3 leads), a diode, and
maybe a fixed resistor in addition to the slide pot. I don't know if
they're doing pulse width modulation or what.
I doubt they have put a stepper motor in there, they wouldn't sell for
20$ each! -- You still should only have two leads coming out of the
motor. Confirm?
Every Dremel tool I've had apart used a universal motor, and the
speed control was a simple dimmer circuit. This one might be PWM, and
run the motor on DC.
Most of the cordless drills these days use PWM power FeT drivers.
I modified a cordless drill with a mini PIC and Bridge to
perform regulated torque control, auto reverse and then forward
again until maximum torque was no longer peaking. Did this so that
the drill would have a TAP mode in it. I stuck a mini pot on the back
side of the handle to set the torque level.
if his dremel is also cordless, It may also be using it a PWM?
who knows. how ever, with the part count, I'm guessing he's using a
corded unit with a phase control.
None of those I've seen used an IC in the speed control. Also, he
didn't mention a filter capacitor, so id may be a simple dimmer
circuit. It's hard to tell from such a vague description. Part numbers
would have been a big help.
BTW, have you seen the small DC powered clone at Harbor Freight? It
runs on 12 VDC, and comes with an AC adapter. I was thinking about
using one (or more, with different sized drills) with a homebrew CNC
machine to drill PC boards.
I took a look at google images for his model and the dimmer really is
just a dimmer ... providing they sell brushes kits (2) for his model,
the principle was ok from the first post; plug it right to the input.
If the person who originally posted the question still follows the
discussion; it is strongly suggested that you do NOT use the tool wired
that way for too long as the motor will overheat and break (or some of
its internals will melt down)... take it as a temporary fix only.