Re: gEDA-user: basic anti-EMI design q

[DJ Delorie <dj@xxxxxxxxxxx>]

> And how do they get into the CPU? Is it a special CPU with 24VAC I/O
> lines dimensioned for 18g wires?

In the furnace system, half the 18g wires are logic and power wires
for the digital thermostats.  The other half are opto-isolated 24vac
lines to the relays in the furnace.  The 24vac lines are 100% opto
isolated from the rest, but that doesn't stop the wires themselves
from being randomly magnetically coupled due to them being furnace
wires and not high speed communication sires.

Had I realized I'd be doing this, I would have had them install cat5
way back then, but this is what I'm stuck with unless I want to start
ripping apart walls to put new wires in.