AboutMatt Coia Expertise I can answer questions about r/c cars and trucks including on-road and off-road vehicles. I am knowledgeable in both nitro and electric powered vehicles. I can also handle questions about repair and maintenance of any wheeled vehicle.
Experience I have owned and raced many different kinds of vehicles. I also help administer a busy website devoted to the r/c hobby. I have done repair work for hobbyshops in the past and have helped many beginners get started in the hobby. I also operate a middle school r/c club.
Organizations ROAR, Mensa, NSTA
Publications www.wnyrcinfo.com
Education/Credentials I am a certified Physics teacher now teaching middle school science and Physics in New York State.
Question Hi Matt,
My question isn't exactly related to R/C stuff, but this was the nearest forum to my subject that I could find, and I saw in your profile that you mentioned knowing about electric motors.
What I'm dealing with is a 120v AC motor, 4 amps, 60 hz and I believe it's about 500 watts or so. While I know how to wire basic circuits, I don't know what the correct rating of potentiometer would be to use for slowing this motor down. I don't have the exact specs for it, but similar models spin at around 5000-8000 rpm, and I need it toned-down preferably between 400-1800 RPM, and for relatively long duty cycles - say one to three hours.
So what I'm thinking is, maybe I could just use a very heavy potentiometer, such as what's used to control stove burners. But I don't know if that would be overkill? I don't want to burn up the pot on the long duty cycle, but I also don't want to inadvertently create more resistance by using a pot too big for the job.
Do you have any ideas? Am I even on the right track with this thinking, or would it be better to just gear-down the motor until I achieve my target RPM range? (I'm almost certain this motor can handle variable speeds).
Thanks for any advice.
Answer Hey Rich,
Thanks for the question. Well, I think you'd probably be fine with either method. Gearing down will be better for the motor (usually more efficient at higher speed) but certainly more complicated to do. I would use whats called a variable transformer or Variac. This would allow you to adjust the input to match your needs. These come in different sizes or you might find plans to build your own on the internet. Check out www.variac.com for ideas (they list by voltage and amps)or check ebay etc for more options. Good luck and let me know if you have any other questions!
