Hi!I just got Arduino Uno yesterday and have tried controlling a servo motor. It worked flawlessly, but I noticed that while servo was moving, the lights on Uno shined a little less, suggesting that motor draws a little too much power (its very small hobby servo, but still...). So I found a 3, 4.5, 6, 7.5, 9, 12 V 300mA power supply and tried connecting the servo's ground and power wires to that power supply with 4.5V set (within servo's range). When I plugged it in, the servo was moving very weird and Arduino IDE crashed, so I quickly disconnected it. Then I read that ground should also be connected to Uno, but I dont understand why. Could anyone please shed some light on this? Thanks!Because the servo is 'reading' a control signal from the arduino it needs to be electrically referenced to the arduino's voltage source, so the external power's ground should wire to both the servo ground pin and a arduino ground pin.LeftyOh, one more thing. Even though the servo has reached its destination, its sometimes still emmiting sounds like its working. Does this indicate that the servo is bad? Thanks!
But does that mean that servo's power supply must be 5V or is it irrelevant? What if I need to control two servos with different voltages and power supplies, do I connect both ground pins to Arduino Uno?
Thank you for this info, but for the core of my question: Sorry, I have formed the question a little weirdly. What I mean is, since Arduino Uno requires 5V power supply (which is usually USB), is it wrong if my servo requires, for example, 12V and so I connect it to power supply of 12V? Will that fry Arduino Uno when I connect the ground to it, since it is different voltage than Arduino Uno requires? Or is the voltage of servo's power supply irrelevant to Arduino Uno?I really haven't seen a standard servo that can handle 12 vdc directly, that will destroy most of them. So your questions kind of confuses me. An arduino can be powered by 12vdc via it's external power connector, but that doesn't deal with properly powering servos with an external power supply. So perhaps you should explain how you wish to power your arduino board (usb or external power connector) and what voltage your servos actually require. You said that you recommend 5V 1A power supply per servo. I have a lot of old adaptors at home that are from devices long gone, some of them are 5V and even more than 1A. Is it okay to use those to power servos?