Frog Juicers  http://www.tamvalleydepot.com/products/dccfrogjuicers.html#hfj

A very easy solution to power polarized frogs, on commercial or scratch built turnouts.

A lot less wiring than the conventional method of auxiliary contact actuated by the switch machine. Basically two wires for the DCC feed and one wire to each frog. The circuitry does the rest.

Works like this: A metal wheel bridging the gap between the rail of the frog and the adjoining rail of the track will create a momentary short circuit if the polarity of the frog is opposite to the polarity of that rail. “Momentary” since the circuit will immediately reverse the polarity to the frog.

The delay is extremely short i.e. not noticeable. Buying the Hex configuration is very good bang for the buck and connecting the board is really “child’s play”.