What kind of variable resistors should i use

Question

i have a 7.2 v battery pack and have an electic motor and it goes to fast so what is a way that i can slow it down by using a variable resistor so i can control the speed?

Answer 1

Some of these motors take a fair amount of current (maybe not hundreds of amps) so resistors become unusable because of the amount of power that they would be required to withstand. This is particularly relevant to variable resistors as they have much lower power ratings than fixed resistors and larger power ones get very big. With large fixed resistors, you could use a switch to change between a number of them.

Modern semiconductor circuits use transistors and pulse switching for this and modules can be bought from a radio control equipment supplier.

Answer 2

You did not say how many amps the motor draws, but a resistor is not a good idea for 2 reasons:  First, the resistor will likely dissipate too much power, and second, the motor torque will suffer.

Here's a better idea.  Assuming that your motor does not draw more than a few amps, what you need is an LM350 regulator.  With just a few parts, you can have a variable voltage control for your motor, and keep its torque capabilities high, too.

Here's the data sheet on the regulator, with a schematic on how to hook it up:

http://www.national.com/ds/LM/LM350.pdf

If you need higher current, then there is a circuit there that will go to 10 amps.

Answer 3

At 7.2V you're probably referring to an RC electric motor --some of these take a few hundred amps --- a DC resistor is not the approach to take as it would require several watts...

http://www.modelflight.com.au/electric_s...

Answer 4

need  more into, like what current or power does the motor take. Or at least how big is it or what is it's intended use.

For all I could know, it's a 10 HP motor.

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