Large Scale Central

What capacitor for a Camel back with sound?

I recently bought a Piko camelback with factory sound and it is great but when it stops the sound stops. I looked at the directions and it looks like I can add an optional capacitor to the board but what type? I’m new to this stuff. The directions show that a +16-24 V positive wire goes to the 4th tab on the board and the negative goes to the first where the reed switch plugs in.
Where do I get this optional capacitor for the Piko camel back?

If you don’t get an answer here try calling Train-Li.

Try looking at the electrolytic capacitors on a ‘keep alive’ board. Those would be the ones that are barrel shaped and usually the larger item on the board. It should be marked with the voltage range and capacitance. Capacitance in mF (micro Farads).

The larger the mF number, the longer it will supply voltage to the desired item.

Possibly contact Greg E. [email protected]

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This is a long shot, but maybe Piko has an optional pack you can get for their sounds.
LGB has them for their sound modules. (I Have a couple of them )

Leaving the throttle set to provide about 6 volts to the

track will keep the sounds, lights and smoke operating

while the locomotive is stopped, such as while standing

at a station. A bit of experimentation will reveal the

proper throttle setting to provide operation of these

“standstill” features. After a time, the sound of the air

compressor pumping will be heard randomly.

The occasional sound of the fireman tossing a shovel or

two of coal into the loco’s firebox will also be heard. As

set from the factory, this only occurs about one of four

times when the loco stops

That is interesting Rooster. I will have to give that a try the next time I’m running it.

I have a capacitor board with 3 caps on it that was a Revolution system product. I wonder if that would work with the Piko? The details are KMG 25V 3300MF. I’m tempted to try it but don’t want to blow anything up. Pos and Neg are clearly marked. I know the MF indicates how long it will last but what about the 25 volt? Does it mean it will hold up to 25 volts? The Piko calls for a 16-24v capacitor. Will this be too much for it? In my limited knowledge it seems that it will charge up to a certain point and not beyond during normal running which is within that 16-24v range.

The voltage rating on a capacitor is the maximum voltage. You should be good.

That Revo item sounds like a “keep alive” and should serve your purpose as-is. I’m don’t know how it was wired with the Revo, but for the Piko sound board, I would connect it to the power feed to the sound board.

I’d say it is a keep alive. Should I skip what the Piko directions say to do and connect it to the power feed to the sound board? Where does the + go and where does the - wire go or are you talking inline ?

I have no experience with keep-alive boards. Did it hook up attached to the power feed on the Revo, or is there a connection on the Revo board for it?

If I were to guess, I’d say it just attaches to the feed wires, like you were powering it form the track or battery. Not really in-line as there is no in and out, only +/- right?

It attaches to the bottom of the Revo board using a plug. I looked it up on the Train engineer Revo site.

OK, then I don’t know the best way to use it.


Yes, that is the manual I have. The questions is, it shows where a “external optional capacitor” goes but it says nothing about the type and I do not think that Piko sells one?

Am I overthinking this? The last thing I want to do is to release the magic smoke.


It will go across the power supply to the sound board. Positive on the capacitor to positive on the board and same with the negative. In-line won’t kill it, it just won’t work. Connecting it the wrong way round however will cause the capacitor to fail, perhaps with a bang (ask me how I know). The capacitor is the right type (electrolytic).

I’m not sure it will keep a sound card going for long (like maybe a few seconds?) - I believe these boards are to deal with glitches in the track supply which are momentary. Won’t hurt to try tho.

I’m on the road for work but I can do a quick check of the expected time and capacitor size needed when I get back. It might be quite a bit bigger than you think - there’s a reason Sierra used a battery.


Sorry gotta do it!

Meanwhile at Todd’s house!!!

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I got Google to remind me how to figure it out. Not to hard luckily, and translates to water quite nicely. Essentially how big is the bucket (capacitance), how much are you taking out (the voltage bit), and how fast are you doing it (divide by I).

I guessed your track voltage at 20V, cutout around 6V like Rooster thought, and a wild a$$ guess how much the sound card uses at idle - not much, and not loud…

Ans is about 1.5s. So to get say 15s of sound, you’d need 10 of those keep alive packs, or a custom build job. Happy to be wrong, let us know what happens if you try it out.


Piko Keep Alive Calc.xlsx (27.3 KB)


No explosions but I have given up on this.
I attached the Revo keep alive to the appropriate points on the Piko board and ran the loco on rollers for a few minutes at about 20 volts then reduced power to stop and the volts of the capacitor had only increased a tiny bit and quickly dropped off. Maybe I do need a battery over a capacitor?

You are correct Rooster. If 6 volts is kept to the track the sound will continue working.

What bugs me about this loco and the new Bachmann Climax is that when the loco stops to reverse and pick up a few cars the sound just stops destroying the illusion.

The tender is back together and maybe I will revisit this at a future date but Thanks so much guys for the help.