[Bill Swindell]

Al, There are many problems to consider.

First, the capcaitor must be HUGE!. To get 1 second or run time from the capacitor, it would have to be close to the size of your engine.

Next, when you first turn on your track power, the capacitor would appear as a short circuit for a short period of time until it charged.

Last but not least, you would have to maintain correct polarity on the capactor at all times. If you ever get the power reversed, it would short out your power pack and release the insides of the capacitor all over the place.

 

[Bill Swindell]

I actually tried what you want to do with an HO streetcar. I wanted an electronic flywheel. I tried hooking capacitors in the range of 1000 mfd across the motor. I saw no change from the motor without the capacitor.

Batteries are a good idea except the really don't like to be discharged to 0 volts.

As for the sound, I just took the electronics out of an LGB locomotive. They have a bank of 10 farad, low voltage capacitors in there. That is how they keep the sound going for a short time after the track power is turned off. Four of thos capacitors inn series would give you 2.5 farads @ 10 volts. You would probably want 16 of these capacitors in series/parallel to give you 2.5 farads @ 20 volts. With that much capacitance, you would probably see some coasting effect on your engine. I never figured out how to handle the reversed polarity when you want to back up.