Hi! I am working on my project and I want to control 3 Servo motors. When I tried to power them directly from my arduino uno it restarts and I have made external supply. Now when there are two Servos connected it works, but when I connect the third servos started to move non stop (as they cannot find theirs position and not responding on my commands. Any ideas what could be the reason for this?
butch_bs:
Hi! I am working on my project and I want to control 3 Servo motors. When I tried to power them directly from my arduino uno it restarts and I have made external supply. Now when there are two Servos connected it works, but when I connect the third servos started to move non stop (as they cannot find theirs position and not responding on my commands. Any ideas what could be the reason for this?
What power supply are you using? (Voltage and current capability.)
And show us your code, (correctly formatted and placed between code tags of course). 
Thanks! founded the problem. The supply cannot handle the three servos. I changed it and now it works. I measured drop of voltage when the 3 servos connected. now it is stable ~4.3V. Is this problem for FS90 servos ( http://shop.rabtron.co.za/datasheets/FS90.pdf )?
butch_bs:
Thanks! founded the problem. The supply cannot handle the three servos. I changed it and now it works. I measured drop of voltage when the 3 servos connected. now it is stable ~4.3V. Is this problem for FS90 servos ( http://shop.rabtron.co.za/datasheets/FS90.pdf )?
Not enough info to comment on the FS90 - the 'datasheet' doesn't mention it's current usage and you don't mention the power supply specs.
You should never power any motors or servos from the Arduino. That leads only to trouble. The usual rule of thumb is to budget 1 ampere per servo.