I own a bunch of old X10 equipment that has gone unused for many years. I ran across it recently and it occurred to me that I could use it to activate xmas lights connected to a few inconveniently located outlets (e.g. they're in places that are great for xmas lights, but not so great for turning on and off). Among the devices I have which I expected to make this possible were the RT504 remote control and the RR501 transceiver. Unfortunately at some point in the dim past the RT504 was stored (translation: "dropped into a box and forgotten about") with batteries installed, so the contacts were corroded to the point of falling apart.

Without using the RT504 remote, can I still address the RR501 somehow? Can the IR543 device communicate with the RR501? My house is very thoroughly wired with IR receivers and my AV closet has repeaters as well as a PC capturing IR, and everything else is controlled with Pronto remotes, so I'd hate to have to break down and add a cheesy X10 RF remote to the mix. I mean, it was fine when I thought I already had one on-hand, but now I'd prefer to just go with IR if I can.

I do have some lamp modules and appliance modules, and I know I could use those with an IR543, I'm just trying to figure out whether this RR501 is now useless without the RT504 controller. As I understand it the RT504 is now discontinued.

Somewhat confusingly, the RR501 documentation I've found says to switch it to "1 or 9" but my RR501 is labeled "1-8, and 9-16"... does this mean the RR501 itself is addressed with the housecode wheel plus the ID 1 or ID 9 depending on switch position? If I recall correctly, the range is because it'll broadcast to that ID range.

Sorry, I know these are probably n00b X10 questions, but I haven't touched (or even SEEN) these devices since about 1995.

McGuireV10, being a noob as well, I can't answer all your questions, but I do have a little bit to contribute.

Somewhat confusingly, the RR501 documentation I've found says to switch it to "1 or 9" but my RR501 is labeled "1-8, and 9-16"... does this mean the RR501 itself is addressed with the housecode wheel plus the ID 1 or ID 9 depending on switch position?
Precisely - the RR501 also can act like a lamp module with the selected address (1 or 9), using the plug at the bottom.
Depending on the age of the RR501 it may only be able to transmit X-10 codes 1-8 or 9-16 (you select which) OR it can transmit all 16 and ignores the switch.

As I understand it the RT504 is now discontinued.
I believe the RR501 is the same as the 4005x from Smarthome, and Smarthome still sells RF remotes for it... so if you decide you can stomach a cheesy RF remote ;) , there are several models to choose from.

I am so cheap I am still using my X-10 components and do not feel the need to step into the 21st century.