I am trying to take control over a trolley. The set up is quite simple. It is controlled today from a switch/pot. Once the switch is on, 12 volts are connected to another cable I suspect is the power supply to the uC in the trolley. The pot then sets the speed. I have left the current set up as is, and override this by using an optocoupler (for the switch) and a digital pot connected to the arduino.
the problem is that the trolley starts rolling once I activate the optocoupler (4N35) is activated, even when the sweep cable is connected to ground on the physical pot.
I should probably admit to a little accident when I first connected the stuff, shorting the 12v switch cable to the common ground. But the trolley still seems to work fine with the manual controls from the potmeter.
xbee--arduino--4n35--switch cables |__ digital pot--diode--physical pot cables
Thanks in advance for any enlightenment...