Zlatko:
I think Simsupervisor make this way:
The circuit:
http://www.mycockpit.org/forums/atta...id=10699&stc=1
The 5 volts on centering pot and ground, must be taken from the same arduino. (or from external power supply, with common ground with arduino.
How its work? Supposed 2,5 volts in PWM (50% dutty cicle), centering pot to obtain 0š deflection on needle.
Now:
If PWM is 5 v, one side of galvanometer is 5v and the other is 2,5v, you get full right (or left) deflection. (left side potencial is +2,5 volts up relative to the right side)
If PWM is 0 v, one side of galvanometer is 0v and the other is still 2,5 v, you get full left (or right) deflection, (right side is +2,5 volts up relative to the left side at 0 volts).
I know i canīt take a PWM like a lineal variable volt, but itīs for simplify the concept.
And the condenser, can be used if the needle got "nervous"....
Maybe Simsupervisor can help if any mistake has be done here...
Regards.
Horacio.