Hi Grumpy Mike,
The +/-10v would be an output, it is the control signal going to the valve, originating from the Arduino
resolution, i would like it to be analog, or fine enough to appear analog. the valve operates full open / full close over a 20v range. 1000 steps seems reasonable 20mv/step?.
would i be stuck to 255 steps since it is going to be tied to the PWM?
power supply - 2x12v batteries...
this 'tester' i am building would also have an lcd output, theres a bit of math to give me a valve percentage, etc. - this is software stuff.
thanks
jon