I've been able to hook up a Futaba S3003 servo directly to my Arduino and it works perfectly. However, when I power it with an external 6 volt DC power supply (instead of the Arduino's onboard 5V) it fails to work.
I'm assuming I need to translate the 5v "language" of the Arduino to the 6v "language" that the servo now uses. Pretty new to this. Any and all help is greatly appreciated.
EDIT: My question, generalized, is how do I use an external power supply, that's more than 5V, with a servo and control it with an Arduino?
Here's a photo of how it's setup (and working).