This weekend I’ve been testing the motors for the Jumbo servo. Adding on from the last test, I put in the L298 H-Bridge module, rather than test with the motor, I used two LEDs wired back to back. This allowed me to confirm that the control code was doing what it should without needing to worry about the motor. It was a good thing that I did as when I added the motor, it tripped some kind of overload circuit in the small 2A PSU I was using.
I got out my big PSU and configured it with a 1.5A limit at 10v. The motor was taking well over 1.5A as it pulled the voltage down just under 5v.
I looked in the drawers and found a smaller motor and confirmed that used a lower current. It ran at just 0.6A at voltages from 1 to 10v so I’ve swapped that in.
Emma Lovelace from twitter pointed out that the longer motors typically have higher torque and hence higher current demands. That will because they have more windings in their coils.
Also this week I spotted a video from James Brunton from XRobots. He shows how to make a servo from an old wiper motor. Couple of interesting points. Firstly, his code example uses PWM for control so if you are interested in running a big servo from RC equipment then checkout his github. The second was that he’s using some IBT-4 motor drivers. These can take a lot more current than my little L298N so these could come in handy for bigger projects. I’ll definitely be checking those out.