Electronics > Beginners
Universal Motor Speed Controller
drussell:
The most important thing will be to wait for the OP to come back online and specify what it is that they're trying to achieve, then we can probably provide better suggestions as to what might work in that instance. :)
made2hack:
Hi all,
Thanks, I had forgotten about AVE's video. It is EXACTLY what I want to achieve, cut the speed of the saw by half (if not more). I don't necessarily mind to get into the electronics of the saw, I was just wondering if there was a straight forward way of doing it with a black box externally.
What exactly is it that makes the motor run at the specified RPM? Is it the internal winding? What I mean is, since the voltage drops by half, and the amperage goes up by 2x, presumably the winding of the motor is what causes a constant power to be sought? IE the winding will always try to draw 2kW, irrespective of the supply voltage?
So, short of rewiring the windings, what would be the next steps? I take it that the winding is sized for the specific voltage that the device is meant to run at, so for 230V, it would be say 18AWG but for 120V it might be 12AWG? Would I assume the same number of turns of winding? Say 100 turns in both cases?
made2hack:
.
Zero999:
Lower speed motors will have more turns on both the armature and the stator. Higher voltage motors also have more turns on both the armature and filed. In low speed applications a high speed motor is used with a gearbox to reduce the speed, which normally works out cheaper than using a lower speed motor.
A phase control circuit could be used to reduce the speed of the motor. If a fixed speed is desired, firstly build the phase controller with a potentiometer and adjust it to give the desired motor speed, measure the resistance of the potentiometer, at that setting and replace it with the nearest standard resistor value.
made2hack:
Thanks a lot, I will look into phase control circuit.
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