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[on:]

I'm building a small robot that uses two continuous rotation servos to drive. It's been working fine from my computer's serial port, but when I run it with a homemade 9V power source the motors won't run. I can tell that the motors are attempting to run (small twitching and noises) but they won't move.

I think the problem might be that the motors aren't getting enough power; should I make another power source and power the motors separate from the Arduino?

[Reply #1 on:]

What 9V source are you using? 9V batteries have poor current capability (and maybe your power source). Motors need a lot of current. Depending on the voltage the motor needs, connect AA batteries in series, negative to GND, positive to the motor's positive terminal.

P.S. If you give us more info, you will get better answers!

[Reply #2 on:]

Hi,

your best bet for running servos is 4 AA batteries, these give the correct voltage required by servos so you don't need any additional circuitry.

see the two links in my signature for an explanation and demonstration.

Duane B

[Reply #3 on:]

but when I run it with a homemade 9V power source the motors won't run

Most hobby servos are rated for voltages between 4.8v and 6.0v. 9v might damage the servos.

[Reply #4 on:]

Hi,

your best bet for running servos is 4 AA batteries, these give the correct voltage required by servos so you don't need any additional circuitry.

see the two links in my signature for an explanation and demonstration.

Duane B

Thanks, I'll try that out later today.

[Reply #5 on:]

Make sure you connect the ground of your supply to the your Arduino's ground.

[Reply #6 on:]

I had a problem a couple of years ago driving stuff from a breakout box I made from a parallel printer port, when the motors only turned when I had my barefeet on the floor and felt a slight buzz when I accidentally completed the circuit..... that was a lack of electrical ground when I hadn't understood to couple the "control" to the "plant" so to speak, so AWOL might be on the right track. (Excpet the OP says the motors are trying to run.....)