It wasn't a huge LED, but it was a fairly high output white one. I saw that it claimed internal pull-up resistors, so I didn't think I needed one. Plus the circuit in the Series1 tutorial didn't use one. Ugh. There was a time when I would have never considered not using one, but I've seen more and more examples of not needing them lately that I got sucked in.
I can't do anything more than ask the gate to open via the relay, but still like the idea of the heartbeat. I guess I can use a mini arduino on the sending side to keep things small.
Anyway, great insight. Thanks. My life would have been a lot easier if I had never seen those series 1 tutorials, but I think you got me straight. Again, many thanks.
--Donnie