# Simple DC motor pressure controller

Discussion in 'Sensors and Actuators' started by DamienM, Sep 7, 2016.

1. ### DamienM

3
0
Sep 7, 2016
Hi All,

This should be a pretty simple one, my daughter wants to make a small project for her school and it needs to be able to operate a small 3v DC motors speed of rotation that will be moving a colored spinning wheel. I was going to use a simple potentiometer however she need to show how force relates to rotation, more force = faster rotation. Most of the kids are doing a simple gear drive with weights but she wants to do something different.

Any ideas for a 3 volt setup? only other thing she wants to be able to do is have it default to a slow speed by default bit like an idling car motor and gas pedal.

Thanks

Damien

2. ### CDRIVEHauling 10' pipe on a Trek Shift3

4,960
648
May 8, 2012
Hello Damien and welcome to EP. This class assignment would appear to be more of a demonstration of basic Physics where the students above are demostrating leverage with gears. Introducing an electric motor into the mix is an example of conversion of electrical energy to mechanical energy. The free running (unloaded) RPM of a motor has little correlation to the force (torque) or work it can do. So spinning a disc will not convey the principles that the instructor is looking for.

You would be far better off driving a heavy flywheel using a 1:1 gear or pulley system followed by a 10:1 ratio that's manually changed. This way the viewer can clearly see that for a given drive voltage and 1:1 ratio the motor won't turn the flywheel but when changing the ratio to 10:1 it will, as it demonstrates basic leverage. These are just suggested ratios but I think 10:1 should be a minimum. You can go greater if you wish.

So there's no misunderstanding, I'm talking about for every 10RPM the motor turns the flywheel will turn only 1 revolution. The greater the ratio the more the torque delivered to the flywheel at the sacrifice of flywheel RPM.

Chris

BTW: This topic should have been posted in the Homework section.