I know nothing about electricity be it ac or dc but I would like to take a small motor, like the ones used in the cheap electric toothbrushes, hobby projects and electronics and slow the rpms down to about 60. I've looked for other small dc motors but they seem to all spin at several thousand rpms. I've tried using batteries with lower voltage but they still spin too fast. I can't tell the rpms, so they may still be spinning at full speed but they aren't near as strong with the lower voltage. Does anyone know if that lowers the rpms or just the torque? Does anyone know a way to reduce the rpms? I'd rather not have to use any gears to change the speed but I think I may have to. Let me know if you have any ideas. Thanks.

Hook it up to a potentiometer (variable resistor) that way you can toggle the voltage going to the motor thereby decreasing the speed. Youd probably have to use something more complex if you wanted exactly 60 rpm or whatever but you get the general idea.

Thanks Ed! That helps a lot. I had no idea what device would do that. Now, off to find one. Thanks again!

just get a 60 rpm motor. Surpluscenter.com , this place is blocks away from my house and they have all kinds of useful shit.

Power into your DC motor works two ways. The voltage applied across the armature will control the rotational speed. The current flowing through the motor determines the torque.

You can also get fine-tuned control of the motor by Pulse Width Modulation (PWM) controlling the power input. In a PWM setup, you apply full voltage to the motor, but at a reduced 'Duty Cycle'; turning it on for 1/x second, off for (x-1)/x seconds. You have to do this very quickly (think hundreds of hertz) but what you get is an average effective voltage much lower than your power source. Most cordless drills work on this principal. Surf the web a bit and you may find some projects related to this.

www.sciplus.com will occasionally have some unique bits and pieces motors with stepdown gearing or other fun stuff.

This motor might work for you it has a speed controller on it and its only $1.50!

Well if you are REALLY worried about power consumption you can use a PWM motor control. It's a pulsed signal where it varies the ON and OFF time to the motor. Where a longer ON and a shorter OFF would have the motor spin faster, and Vice-Versa.

It might be helpful to know the application for this motor. What's the plan?

Sorry I haven't been back for a while.

matzner, I'll have a look there. Thanks for the suggestion.

spoonsprout, what you say makes sense but is still a bit over my head. I'll definitely have to learn more to implement that information. Thanks for the providing it.

mdmfootball, that is definitely in my price range but it may be kind of big for my application. I would like it to be easily held in one hand.

MyYz400, Thanks for the suggestion. It sounds like what spoonsprout was saying. I'll be looking into that.

APHawkes, The plan is to make something like a battery powered toothbrush or dremel in design but that will ideally have a variable speed from just a few rpms to maybe 60 or so at top speed. It will only have to be able to drive a 3/32" shaft that would probably be around 10" long and weigh no more then an ounce or two with a full load. And hopefully the motor and controller will all fit into a light weight hand held cordless package. So pretty much just like a battery powered toothbrush but at a much slower speed.

I was looking at all the motors and potentionmeters on www.allelectronics.com but I have no idea what any of the specs really mean or what specs I should be looking for that will meet the needs I stated above. If any of you have any time to kill and want to suggest a specific motor and potentiometer that might work, please do ;o) Meanwhile, I'll be trying to educate myself on what you all have already shared. Thanks again for all the input.

A suggestion... Perhaps you could take apart a servo from an radio-controlled model (airplane, car, etc). They contain a small dc motor, a potentiometer, work off batteries, drive small shafts, turn as slowly as you want, and should handle a few ounces OK. Bonus: they are bi-directional!

Thanks for the suggestion. I don't have any remote control vehicles at my disposal. Can I just buy the parts? Are they inexpensive? I'm looking to make several of these, not just one and hoping to have less then ten bucks in parts. Maybe more if necessary.