Well, I finally have a single turnout with a powered frog! It wasn’t all that difficult, really.
I cut a couple of lengths of green 22-gauge wire and connected each to terminals 2 and 3 on the SMAIL, in addition to the wire already connecting the frog itself with terminal 4 (see my last post).
I cut two more lengths of the same wire and suitcase-clipped one to a red bus and one to a black bus. Then I twisted each pair of wires to connect them and tested the turnout. It didn’t short, so my guess at polarity was accurate. The SPDT switch inside the SMAIL was now active, and routing power/switching polarity as needed.
I soldered the twists of wire, then isolated them with shrink tubing.
Testing the engine was a complete success. The Bellwether, my little 0-6-0, can crawl very slowly over the turnout even if the points aren’t touching the rail.
There is one drawback:
When an engine reaches the fouling point (the short section of track between the frog and the isolated rail joiners), if the turnout isn’t already thrown in its direction, the engine immediately shuts the layout down because the metal wheels bridge the polarity gap and cause a short circuit.
Before, when the frog was dead, the engine simply stopped when it reached the fouling point, without shutting the entire layout down.
The benefits definitely outweigh this drawback. Engines shouldn’t approach close to the fouling point anyhow unless the switch is thrown in its direction. That’s just good prototypical operation. Entering the fouling point is the railway’s equivalent of nosing your car into an intersection when cross-traffic has the right of way.
Anyhow, I will post a video of the engine crawling over the turnout once I reclaim my YouTube account, for which I’ve forgotten the password. Maybe tomorrow evening.
Edit: I stayed awake later than I planned and powered another frog. This time, my guess at polarity was wrong and caused a short. No worries; that’s why I simply twisted the wires. All I had to do was swap the pairs and test again, then solder and heat-shrink.
Edit II: After another six hours or so, all the frogs are powered! I wish I could say I found a groove, but in reality each SMAIL and turnout had its own quirks and challenges. Also, I was in kind of a gloomy fog this weekend, but it was like a ray of light when I retested all the turnouts and each worked perfectly.
After briefly cleaning the railheads, the Bellwether can crawl at a very slow speed which appears to be roughly the equivalent of an N-gauge walking pace, and it doesn’t get hung up on the turnouts.