Question about a battery powered turntable

Adam Baker · Post by **Adam Baker** » Wed Mar 02, 2011 6:41 pm

I picked up a battery powered turn table/display base at the last meeting of hte model club I attend, and I was wondering if its possible to slow down the rotation of the display. Right now it rotates at 12rpm, and I'd like to slow it down so its only 3-5 rpm at most, which would make it much better if I wanted to display a figure on it.

Could I install some kind of rheostat in it so that I can adjust the speed?

Mad-Modeler · Post by **Mad-Modeler** » Wed Mar 02, 2011 6:53 pm

Some of the turntables can be set to 2 speeds, bassically you can change the gearing.

You could install a dial switch to reduce the power to the motor but that would also reduce the torque and the model might be too heavy to allow for rotation.

I would look at the gearing/gear ratio.

USS Atlantis · Post by **USS Atlantis** » Wed Mar 02, 2011 6:57 pm

Unfortunately, motors are different beasts than lights - reostats are nothing more than high-power potentiometers

All they do is vary the voltage coming through, and if a motor doesn't get it's necessary voltage, it just doesn't run.

What you want is a Pulse Width Modulator - it incorporates a pot with a control circuit that just sends pulses of power - at the correct voltage

What this basically does is start-stop the motor in precise time periods so that the AVERAGE speed is reduced - the pulses happen at such a rate that you would need a timing disk and a strobe light to determine the speed differences

Chacal · Post by **Chacal** » Wed Mar 02, 2011 7:05 pm

Have you taken the turntable apart? Does it have gears, belts?

Adam Baker · Post by **Adam Baker** » Wed Mar 02, 2011 7:33 pm

Nope, unfortunately no gearing or belts. Just a small electric motor.

So I guess I'll just leave it alone. The base itself is only about 4" in diameter, and its a hemispherical shape, so I dont think there's enough room to fit a pulse width modulator in it.