So I have successfully interfaced a servo with a arduino and a pot, and can change the position of the servo with the pot. When the boarduino is hooked up to the PC with the FTDI cable, there is only a slight wiggle in the servo position. When I disconnect the FTDI cable, the wiggle becomes more prominent, like 15+ degrees. The wiggle has a frequency of about 0.5 hz.
The Boarduino is externally powered, and I am using a converted ATX powersupply as a benchtop supply.
I've tried a filter cap between the servo power and ground, but that doesn't seem to be the issue.
I assume somewhere, that I have a voltage that is floating?
Weird, I just noticed when I grab the metal base plate of the breadboard, the wiggle becomes more prominent even when the ftdi cable is plugged in. Perhaps my power supply ground isn't robust enough?