DKWatson:
I've read in a couple of posts here about a 200 ohm resistor. Sorry lads, that ain't goin' to cut it. Do the math.5 / 200 = 0.025 that's 25 milliamps and about 3 times what you should be limiting your input pins to. These are logic levels!! You're not trying to operate a servo motor!!
Yeah, I did do the math. I was simply trying to keep the guy from frying his Arduino pins and AVR.
Another concern I was taking into consideration was cable length.
He hasn't said how long his cables were and we don't know anything about the construction of them, so I was trying to insert the least amount of resistance to protect the Arduino pins and AVR while trying to minimize other potential issues for longer cable lengths.
But like subsequently said, I think it would be much better to ground the remote end vs drive it with voltage.
--- bill