potentiometer

Is a 120 volt AC potentiometer the same as a cheap light dimmer?

I want to slow a 1/25 HP 120VAC motor, and the manufacturer says I should use a potentiometer but it's not clear just what that is.

Will an inexpensive light rotary light dimmer switch do it, and is that the same as a fan control speed switch?

What should I use to slow down a motor?

yes but uhh.... not sure I'd use a light dimmer to slow a motor. I think the worst that would happen is you'd burn up the dimmer. Or start a fire.

A potentiometer is like a rheostat.

What should I use to slow down a motor?

0.7 amps at 115 volts or 80 watts.

Quote from Dr. J : yes but uhh.... not sure I'd use a light dimmer to slow a motor. I think the worst that would happen is you'd burn up the dimmer. Or start a fire.

The dimmer would get super hot, melt into itself, and short-circuit.

Quote from batterycharger : What should I use to slow down a motor? 0.7 amps at 115 volts or 80 watts.

A potentiometer

Quote from batterycharger : Is a 120 volt AC potentiometer the same as a cheap light dimmer? I want to slow a 1/25 HP 120VAC motor, and the manufacturer says I should use a potentiometer but it's not clear just what that is. Will an inexpensive light rotary light dimmer switch do it, and is that the same as a fan control speed switch? What should I use to slow down a motor?

Is the Magic Wand too powerful for you?

Use a rheostat for a ceiling fan like you can find at the hardware store. DON'T use one for lights. Make sure it is good for at least 120VA (volt amps). Should run you about $25-$35.

They all look the same to me, those things that go in the wall box, but I'll do that.

Depends upon the rating of the dimmer. Something like this would probably work:

http://www.harborfreight.com/rout...43060.html

Router Speed Control

Quote from zzyzzx : Depends upon the rating of the dimmer. Something like this would probably work: http://www.harborfreight.com/router-speed-control-43060.html Router Speed Control

That thing is a piece of crap, and I'd advise heavily against it.

OK, would you be OK with a better branded one?

A rheostat/potentiometer slows down the motor by intentionally wasting power, AKA generating heat, and it can get very hot even with a 30W motor (1/25 HP). A modern dimmer or speed controller instead uses a triac, which rapidly turns on and off completely, so it wastes little power and stays far cooler, regardless of the speed of the motor or brightness of the lamp

I'd be scared of using a motor controller from Harbor Freight because the quality of their electronic products tends to be very, very low, but HF is really good about warranties, at least during the first 90 days. OTOH about every light dimmer sold at hardware stores, Wal-mart, and Home Depot is UL or CSA approved for safety, so as long as you put it in a steel box and use a 3-wire grounded power cord, you shouldn't have to worry about fire or electrocution.

A fan speed control switch selects among different motor windings, but a 2-speed motor can also be controlled by putting a diode in series when it's desired to cut the voltage in half. A diode rated for at least 3 amps and at least 400 volts peak inverse voltage should work fine with for this. Even though a 1/25 HP motor doesn't draw more than 1/4 amp, you want the diode to be rated much higher to withstand surges. Whether you use just a diode or a light dimmer, install a fuse ahead of it that's rated for no more than the maximum amp rating of the dimmer or diode.

At one time Radio Shack used to carry stuff like Potentiometers, but not sure if they still do...I tend to avoid going into crap-shack for the most part.

The op could look at some of the woodworking sites for a better quality Router Speed Control that was posted above but from Harbor Freight.

I agree with TR and that anything electrical in nature from HF is of questionable quality and durability...I'd hate to be jury-rigging something together using their stuff vs. what they were actually designed for, like using a router with that Pot.

Quote from The Raddish : That thing is a piece of crap, and I'd advise heavily against it.

But...it sure looks purdy!