vinceherman:
A 9v smoke detector battery? Also not a proper power supply.Try 4x AA batteries to power the servos. Use common ground.
That's why I tried creating a voltage divider: Vout = [R2/(R1+R2)]*Vin
With, my Vin as 9v and R1=R2=10kOhms, it should be 4.5 V, or roughly 3x AA batteries
It's just your garden variety 9V battery. Im sure you could use it in most smoke detectors.