Electric Motor Speed Control

[DavidUK]

My son has built a model of a fairground ride for a school project. He used a small electric motor powered by a 4.5 V battery to drive it but he said he wanted a speed control for it. So I fitted a potentiometer in series with the motor. Unfortunately, the potentiometer was 1 kOhm and the working range for the motor to run was tiny (~0 to 5 Ohm) so it was virtually a switch. Also, the potentiometer burnt out after a while.

Any advice please on this? Do I just need a potentiometer with a lower resistance but with a higher power rating? Is it possible to get such a thing?

[Space]

I don't think this is the proper way to plug a potentiometer... if it has 3 connectors
When I was at school we used them that way:
http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/info/com p/passive/resistor/pots/pots.htm

[DavidUK]

Thanks Space. I did try connecting it as you suggest (i.e. as a potential divider) but the problem is that the electric motor resistance is so low compared to the potentiometer resistance that it doesn't make any difference.

[sddsddean]

Just thinking aloud here David. You want a potentiometer that will work with a fairly low power rating (I think). How about the volume control off an old portable radio? I've got no idea what the resistence etc would be; just trying to think of where you could get something that may work fairly easily.

[Thunderchild]

try this

http://img222.echo.cx/img222/5053/mot5hm.jpg

the value of R should be battery volts/max amps that go thru the base of tr is u use the mA value u will get the value straight in Kohms. for the value of the pot make that 1 tenth of R and make sure the TR can carry the current required by the motor that can even be an amp or more so a heat sink is probably needed.

[DavidUK]

Thanks Thunderchild - that looks good.

[precision-elec]

Variable frequency drives help to control the speed of the motors. It helps a lot to save energy as well as regulate speed. When you install variable frequency drive in any motor, it helps to increase the speed of the motor as well as ensure efficient workings of the motor.
https://www.precision-elec.com/motors/