The Garage of Evil tutorial calls for using a Pony PET-120-12-60 power supply, but no store around here had one in stock. I was going to buy one online, but did a little online searching and found, first, that these are called transformers (I didn't know that ahead of time, and when I tried to explain it to people they had no idea what I was talking about).
Once I knew what I was looking for, I went to Radio Shack and was able to find what I needed: I got a 12.6 VAC, 3 amp power transformer (it was Radio Shack part number 273-1511B).
I also bought a basic dimmer switch from Lowe's:
While the GoE plans also calls for a switch-outlet combination, I didn't figure that was going to be necessary. While I'll get a project box for the parts, the double gang box I originally bought won't fit the RS transformer. I guess that's one of the benefits of the Pony model, it's more compact than this one. But I wanted to cut foam now, so I went with what I had available.
I also bought alligator clips which I connected to 16 gauge wire I had available from my LED light projects.
It was then time to hook up the transformer and dimmer to the plug wire I salvaged from the train transformer. The GoE directions were essential since there are a heckuva lot of wires and no real rhyme or reason to them. Following the schematic, I hooked up all the wires, though I had two yellow wires coming out of the transformer instead of blue.
Also there were no white wires on any of my components, everything was black or yellow so it was a bit of a guess as to which went where. Maybe it doesn't matter so much. Either that or I guess right. Obviously I bypassed the switch/outlet part.
I connected the transformer to the alligator clips, which in turn were connected to the guitar wire.
Here is a look under the table showing the other connection at the PVC arch:
I plugged in the setup and with fingers crossed I turned on the dimmer. There were no sparks and the circuit wasn't blown so it seemed to be working. A quick touch of the wire showed it was hot, so I shoved some foam into it and success!
I definitely didn't bring anything new to the discussion here, and I suggest anyone looking to build this power supply themselves to follow the Garage of Evil tutorial. It was a big help.
One note of caution: I wanted to see how high I could crank the power on the dimmer and put it all the way up. It didn't take long for the wire to turn red hot and then pop! About half the way provided sufficient power and I sacrificed the wire just to see what would happen.