I have a small HO scale 0-4-0 steam switcher locomotive that loses power when going through switches that do not have powered frogs because it only picks up power from one of the 2 axles and cannot bridge the frog to get power. I want to put a capacitor in it to power it across the switches. 1. What size capacitor would I need? 2. How would I wire it so that it would work in both forward and reverse? Max voltage is about 15 volts and max current draw is about 3 amps. 3. Is this the way to go or is there a better solution?