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I've got a 1.5v DC motor that I'd like to slow down. I'm not sure how to slow it down and use a larger battery. I'm good with a soldering stick just need a little help.
But this just varies the voltage like the divider. The PWM solution suggested is the best way to do it.
You don't understand. Reducing the voltage is exactly what you need to do. Using a regulator gives you effectively a zero output resistance supply, so the motor runs extremely well regulated, even down to very low speeds, where PWM is often not very good. There are plenty of good reasons to choose PWM, but they aren't "Easy" as the OP wanted.
Well regulated? It isn't me who doesn't understand. Operating any motor at lower voltages than it is designed for reduces torque as has been pointed out already, and causes the windings to overheat. PWM maintains almost constant torque even at reduced speeds because the full voltage is being applied in bursts.
Torque is a function only of current in a DC motor, not of applied voltage, it is an amateur mistake to believe that voltage controls torque.
Overheating is NOT caused by running the motor at lower voltages, its caused by excessive current in the armature which in turn is caused by taking more torque than the motor is designed to provide from it. Since V=E+IR, where V is motor terminal voltage and E is the back EMF and I is the motor current and R is the armature resistance, as E falls (you slow the motor down by applying a mechanical load, I increases and the armature losses increase.
Available torque goes DOWN with increasing speed. Available power from a DC motor is maximum at the rated speed. Available torque is maximum at zero speed.
PWM is nothing magic. A regulated supply with effectively zero output resistance works JUST as well as a PWM system, only for larger motors it isn't very practical.
Get some good books on electric machines and read them.
The only thing I can conclude is that, if you have to rudely insult the intelligence of me or anyone else, in order to 'win' an argument, you've already lost the argument. Any point you made after that, whether it has any merit or not, mostly NOT, is invalid because you have lost all credibility at this point. Intelligent, knowledgeable adults make their point WITHOUT acting like trolls, and with logical explanations of the FACTS. They back up those facts with references to source material. They don't make the 'amateur mistake', to coin a phrase, of reading, but not understanding, a few articles they found on the net and then mixing and matching buzz words and ideas, while being rude and insulting, in a futile attempt to bolster their own ego, and "prove" their "point". That's all I will say. Next time I will just flag it as 'not nice' spam.
Funny I came upon this old thread... I am attempting to slow down a small rotating motor for a mobile. I hooked up a potentiometer but it slowed the motor down over a 3º-5º turn. Is there a certain potentiometer to use where I can get at least a 180º turn from 0volt to the 1.5v max? Or if I don't care about varying the speed how do I know what ohm resistor I could put in the circuit to slow the motor down by 25%, 50% or 75%?
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Posted:Oct 19, 2009
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