Forgive me if this comes off as condescending. I do not mean it that way. The fuss over frog is important. It is for Joel, it was for me. I am merely boiling it down to its brass tacks.
All of the following assumes dead frog is not an option.
Powered frogs, to prevent stalling, need some method of aligning frog polarity with point movement. Juicers (incl SmartFrog) do it by short detection so there is no user interaction. Switch machines also make it automatic through micro switches, etc. Conceivably it could be done with parallel wiring/switching with turnout motor fascia switches. Or with micro switches hooked to manual ground throws, etc. Shucks, in this day and age, it is likely an Arduino or other micro processor solution exists out there. Regardless of the mechanism employed, ultimately frog polarity control without direct user intervention is the desired outcome. Am I correct Joel?
The RP issue that compounds the problem is all popular frog juicers are designed for square wave AC short detection (DCC). Passing DC through them may or may not work with probability leaning heavily towards won't work. Detectors (juicers) that rely on an inductive coil to sense current (most products) definitely won't work the same or at all. The signal being monitored will be different for DC through an inductor compared to AC through an inductor. The device has to be designed from the get-go to detect DC current rush. Hall Effect devices come to mind. The Ring AR-1 is an example of such device. It is designed to detect DC current, without the use of an inductor, and so could be used to power frogs. Although at $39.99 a pop it would be an expensive way to go.
If I understand correctly Joel is seeking a practical short detector and polarity reverser for DC operation. The SmartFrog sounds like a possible solution. My concern is the fact the SmartFrog is a mechanical relay device. We know from years past relay based devices work. But we also know they are slow in response time and as a result tend to have a lot of serious arcing going on at the wheel/frog. The old turn-out-the lights-run-trains observations. It would be beneficial to find an all electronic device with transistors that operate at near instantaneous speed i.e MOSFETs with a fast drain. Exactly what the DCC crowd enjoys with current frog juicers. Transistors if for no other reason than to reduce the wheel/frog pitting that will eventually result because of relay action.
And, as Joel rightfully is concerned about, compatibility with RP products namely power supply. What if the SmartFrog relay action is slower than the trip action time of the Ring power supply internal circuit breaker? Only way to know is to try it. And even if it works you won't know if it will work every time everywhere. Wiring length, bus impedance, supply load, and many more variables are in the equation.
The "allow the mistake to happen (short circuit) and then quickly resolve it (reverse polarity)" is, in my mind, a poor approach to the problem. No denying it is a popular approach. I just don't like it and have rambled on this forum about it in the past. I am of the opinion it is better to not allow the problem to occur in the first place. This brings us back to frog polarity controlled by points position. Either flip a toggle switch or tie it to switch motor contacts. Done.
