Stayin’ Alive

My March 2013 column in the free to the reader online Model Railroad Hobbyist magazine (CLICK HERE) featured the TCS KA series of Keep-Alivetm modules, as well as come comments on using extra energy storage capacitors.

Rather than recreate the wheel, I’ll refer you to that column. - CLICK HERE.


The SoundTraxx Tsunami page had the following information. I’m retaining it here for historical reference.

My loco stalls on turnouts or doesn't run smoothly, I want to add an external capacitor.

The Tsunami is already set up for a small external capacitor. The external capacitor (220 uF) is a start. For best performance use as large a capacitor as you can physically include in your installation: up to 2500 uF or so! Litchfield Station sells capacitors for this purpose. They need to be rated at 25 volts or higher. Bruce finds that 2200 uF in parallel with the 220 included on the decoder works nicely. If you can't fit that large a capacitor, try several of the 470 uF capacitors. Wire capacitors in parallel, observing polarity (plus to plus and minus to minus). Insulate your connections.

THE DOWNSIDE TO THIS is that the inrush current to large capacitors may exceed the capabilities of your Programming Track Booster or trip your circuit breakers or system protection circuit and it may not reset! PSx series circuit breakers are designed for operation in this environment.

Another way to mitigate the impact of the additional capacitance on your layout, if you have the room, is to add a resistor and diode, as shown below. The diode can be any rectifier (1N4001 or similar). The green wire in this circuit goes to the black capacitor lead on a TSU-1000 series decoder; it goes to the black with green stripe wire on the TSU-750 series decoders. Use the resistor value shown in the table.

Capacitor Value

Associated Resistor Value

Up to 2200 µF

100 ohms

Up to 4700 µF

220 ohms

Up to 10,000 µF

470 ohms


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