DVDdoug:
Ok so I need an op amp that I could hook up to the same power supply as the Arduino board, get the 0-5 out of the board and amp it up to 0-10.
In case you don't know this, you'll need a slightly more than 10V powering the op-amp. Then, you just need an op-amp circuit with a gain of 2 (an op-amp and two resistors).
The Arduino doesn't have a true DAC. It has PWM which can be filtered (with a resistor & capacitor) to get a variable DC voltage.
Thanks for this! I was just doing some research about it. I bet the ballasts don't like PWM, so I I'm going to need a DAC. Looks like this guy already did all the hard(ware) work for me:
If I'm not mistaken, the Arduino seems to accept 12 V input power, which I'll feed to the DAC opamp as well. Well, actually I need both 12 V and 5 V... like an ATX power supply, but with a lot less power output. Maybe I could just drop down the voltage from 12 to 5 with a resistor because the currents are so small? I don't have much experience with low current electronics... don't worry, I know how to handle mains power.
I can even calibrate the output voltage to exactly 1-10 V with software. I'll measure the voltage with different output values and get a lower and possibly upper limit. It seems I can even read the output voltage directly from the Arduino... double check with a volt meter first. Looks great! Only worry now is that if the that DAC outputs only 9.9 volts or so, I will not be getting full output from the fluorescent tubes... maybe a potentiometer at R4 to adjust it?
All I need now is to add a couple of relays to turn the lights on and off.