What is a Frog Juicer?

A Frog Juicer is a small electronic circuit that will automatically switch the polarity of a powered frog in a turnout. It can detect the presence of a locomotive on the frog, and if the polarity of the frog is the opposite of the locomotive, it will switch it to match. It does this at an undetectable speed without causing the engine to stall or the sound to be interrupted.