Electronic – Driving a small motor: What’s needed


This question is very basic, but I'd like to ask it anyway.

I need to drive a small motor. I'm thinking about connecting it directly to 4 AA batteries and using a simple switch. Is there anything else needed?

Also, it its datasheet unit gcm is mentioned. What is it? I thought that torque is measured in N*m or similar units.

Best Answer

gcm is gram * centimeters. The stall torque is listed as 340 gcm. This means that if you stuck a pulley with a radius of 1 cm on the shaft, wrapped a string around it, and tied it to some weights, it would fail to lift more than 340 grams.

Your strategy of 4 AA batteries and a switch will probably work. If the system involved digital electronics, you'd want to add a diode in parallel with the motor to prevent voltage spikes when you opened the switch. (Google "flyback diode.") You'd also want a capacitor in parallel with the motor to filter out high-frequency electrical noise, which would scramble the rest of your circuitry. But for a small motor and a mechanical switch, you'll be fine.