Hi John
Yes there are wonderful "things" (Supercapacitors?) to fight against poor current pick-ip BUT:
- nothing beats a clean track
- avoid using sand paper or abrasive materials (only grade 1000 and above)
- make sure the pick-up issue is not coming from the loco :poor slider status, poor ground return (because of dirty / greasy axle bearings / insufficient number of ground return
- Supercapacitor mean the loco keeps on moving and not stoping in front of signals or NOT receiving latest digital order.

So, in short (only my opinion) these energy storage things do not replace the need to have clean tracks.

Having clean tracks is easy: just use your trains regularly. Stop using them for 1 month or more and then you are in trouble.
Cheers
Jean

I did it once, back when supercaps weren't really a thing yet:



As far as I remember, it didn't hurt the performance, but it didn't do much good either. It was an old Delta lok converted to digital, and the motor simply used too much power for the capacitor to be able to help with anything but the tiniest of contact problems.


You can't just put a cap on the power from the rails. The power is AC (also in this digital age), and capacitors don't like AC. They tend to go BOOM from it.
You will have to get the rectified DC voltage from the decoder and add the capacitor there. Not all decoders provide easy access to both + and - from the rectifier.

Capacitors work great against flickering of low power led lights, but not for direct track power (M digital is not DC). I melted one doing the experiment. Cap should be after AC to DC rectifier, so decoder to motor connection. Not sure what size capacitor is needed to power motor, but greater than typical 470 uF for led light. Longer shoe contact of locos and occasional track cleaning usually does the job.

I also install them in all locos, and wagons with lighting. They simply never stop nor flicker any more. Indeed, the straight-forward instalation is on a decoder (find the ground and voltage after the rectifier) and 2200 uF 25V is plenty enough for smooth running. That gives you ~half second.

A few extra details:
- use the diode||resistor+capacitor circuit, to prevent spikes in current when starting up, due to cap charging
- 25V vs 35V caps: they are significantly smaller at the same nominal capacity (that the 35V ones would not make use of)
- with a 18-19V power supply and diodes that shape the digital signal & diodes that rectify it in the decoder you are left with 1-2V less at the capacitor, 18V tops thus. So even 25V have a large safety margin.

So my advise is to install the largest 25V cap that fits the equiment :)

It's a very simple addition to the cap. ESU's documentation has it detailed, you can see it here:

http://www.sbs4dcc.com/t...uloksound5keepalive.html

and check out marklinofsweeden's video on how it's done here (from minute 6 onwards):

Keeping alive a LED lighting, that draws few milliamps, or a running engine are different matters

2200 µF sounds big, but such a capacity is used to reduce the trickle in an AC/DC converter. At 1 A it lasts a few milliseconds.
A Gold Cap capacitor has 1000000 µF - enough to power a loco for a few seconds, but requires a considerable amount of electronics (voltage step-up and such) to get it working.


AFAIK some Roco DC motors in H0 models draw 1.5 A.
Some DC motors draw a lot, some AC/DC motors draw a lot.

I just searched for "marklin analogue voltage" and found your posts on it. And went further to read about the reversing voltage. Glad I don't have any of that around and will thus keep everything well below 25V :)