On 5/26/06, Spehro Pefhany wrote: > A 1000' pair of AWG24 wires has a loop resistance of about 51 ohms at 20= =B0C. > If you're going to be using, say, 470R series resistance, the voltage > drop for 50-400' is hardly significant as far as visual brightness goes. So in theory for my simple version I can basically just ignore the cable. Everything is going to be very simple in that it will just be switches and LEDs - there shouldn't be much to get harmed by picking up interference. Right? Once I move to the more complex version with actual electronics driving the long lines, I will have to revisit that protection again. The RS485 driver idea is kind of cool...in theory it would be able to control the LEDs directly. I'll have to see what the output of the drivers is to see if it has enough oomph to light a bright LED. The advantages are many - I can drive the driver easily from a PIC and if there is some sort of horrible lightning strike or whatever, the chips are cheap and can be sacrificial (assuming I use 75176's...I have over 200 just sitting around). Thanks! Josh -- = A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist