Using a transistor to drive a servo.

Other Hardware General Electronics
21

ThatGuy007:
Awesome, you guys answered my question perfectly. I didn't have the intention of using pwm but i hadn't thought about when the signal goes low. I will be looking into switching regulators then.

It's somewhat strange though, i vividly remember using a darlington transistor on a servo to provide enough current a few years ago at the advice of my professor. Any ideas how it could have been implemented?

Not a clue here. Keep in mind that the current draw by the servo is a very dynamic thing. With the servo stopped at the desired PWM controlled signal the servo may only draw 7ma, but when commanded to move full travel with a heavy load it might draw in excess of 1 amp.

22

After re-reading grumpy-mikes post i think i figured out what i may have done. I probably used the arduinos +5v constant pin as the base of the transistor. I didn't realize the servo library pulsed the pins, that would indeed create a problem. But i think with that simple change the circuit should work. 1a is alot of current, that be nearly 7W do dissipate! I'll look for a switching regulator.

Thanks guys!

23

I am not sure we are winning here ...