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Capacitor installation for Loco Decoders/Dirty track?
 Joined: 05/12/2004(UTC) Views messages in topic : 2,976 Location: CA, USA
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Hi everyone, I am curious if any of you have ever used a capacitor (or similar) when doing a decoder installation, in order to keep the loco/decoder alive over dirty patch of track or similar moment of poor contact? its a problem I don't have at home since I have no layout  , but see plenty of issues with on modular layouts or at friend's houses who aren't as diligent about cleaning track It seems like an obvious thing to do if you have the room, and I was debating installing a few myself, but thought I'd ask for tips and tricks here first. In theory one in line between pickup shoe and decoder will make a big difference? I was looking at 2200uF 35v Cap as a good option, but not sure what a loco actually draws for power and if that will cover it? Thanks in advance for any tips! |
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 2 users liked this useful post by 5HorizonsRR
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 Joined: 04/02/2011(UTC) Posts: 3,563 Location: Paris, France
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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 |
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2 users liked this useful post by JohnjeanB
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Joined: 05/12/2004(UTC) Views messages in topic : 2,976 Location: CA, USA
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Jean- excellent point about the signals- reason enough for me to think twice about adding one...
I am obsessive about clean tracks at home, so no concerns there :) |
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 Joined: 10/09/2004(UTC) Posts: 959 Location: Copenhagen, Denmark
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Originally Posted by: 5HorizonsRR  I am curious if any of you have ever used a capacitor (or similar) when doing a decoder installation, in order to keep the loco/decoder alive over dirty patch of track or similar moment of poor contact? 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. Quote:In theory one in line between pickup shoe and decoder will make a big difference? 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.
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1 user liked this useful post by Mikael
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Joined: 12/08/2006(UTC)
Posts: 9,277
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Originally Posted by: JohnjeanB 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 Märklin present new lighting for the wagons and it has capacitor. Yes you must clean Märklin tracks too. |
H0
DCC = Digital Command Control
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Joined: 04/02/2021(UTC) Posts: 483 Location: USA
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Originally Posted by: 5HorizonsRR Hi everyone, I am curious if any of you have ever used a capacitor (or similar) when doing a decoder installation, in order to keep the loco/decoder alive over dirty patch of track or similar moment of poor contact? its a problem I don't have at home since I have no layout , but see plenty of issues with on modular layouts or at friend's houses who aren't as diligent about cleaning track It seems like an obvious thing to do if you have the room, and I was debating installing a few myself, but thought I'd ask for tips and tricks here first. In theory one in line between pickup shoe and decoder will make a big difference? I was looking at 2200uF 35v Cap as a good option, but not sure what a loco actually draws for power and if that will cover it? Thanks in advance for any tips! 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. |
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 Joined: 21/05/2004(UTC) Posts: 1,768 Location: Brisbane, Queensland
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I use the ESU powerpack on my small locos and they are a saviour, otherwise I would have to sell the models - such as Glaskasten, T3. https://www.marklin-user...ksound-5--powerpack--LEDGiven they are all small locos, size is a huge factor so you need the ESU powerpack since it has the circuitry to support the smaller super capacitor. You can use standard caps wired without circuitry but they only fit into larger models which don't need it anyway. I have had some issues with ESU powerpacks though, one had a DoA supercap (which I replaced, the supercaps are only ~$4) and one that won't work even with a new cap, so its a write off. That is all of course for locomotives. For wagons I will be using one decoder with capacitor per train with current conducting couplers. |
modelling era IIIa (1951-1955) Germany |
1 user liked this useful post by applor
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 Joined: 20/08/2018(UTC) Posts: 157 Location: Geneve, Geneva
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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 :) |
JMRI on RPi & DCC++ / C-track / Marklin, Roco, ESU, Bemo locos / Christmas car collector |
4 users liked this useful post by costing
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Joined: 05/12/2004(UTC) Views messages in topic : 2,976 Location: CA, USA
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Lots of good inputs here- thanks! I have no layout and am a complete nut about wheel cleaning, so no problems here  Now those "guest layouts" with dirty track I can't say the same for... This may be more of a headache than its worth if the simple cap isn't a fix. (and a good point about inrush when several such locos are sitting on a layout trying to "charge up" Lots of interesting learnings, although leaving my trains alone seems to be the solution! |
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Joined: 20/08/2018(UTC) Posts: 157 Location: Geneve, Geneva
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JMRI on RPi & DCC++ / C-track / Marklin, Roco, ESU, Bemo locos / Christmas car collector |
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Joined: 12/08/2006(UTC)
Posts: 9,277
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Märklins new lighting with capacitor works about 3-4 seconds!
There is a video by Märklin they did show up.
Seems promise for the future Märklin locomotives? |
H0
DCC = Digital Command Control
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 Joined: 28/03/2007(UTC) Posts: 303 Location: Torino,
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Keeping alive a LED lighting, that draws few milliamps, or a running engine are different matters
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1 user liked this useful post by mario54i
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Joined: 12/08/2006(UTC)
Posts: 9,277
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Originally Posted by: mario54i Keeping alive a LED lighting, that draws few milliamps, or a running engine are different matters DC motors don´t draw so much in power. Märklins old AC and old 5 pole DC motor draws a lot! It´s different matters by use capacitor too. |
H0
DCC = Digital Command Control
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Joined: 16/02/2004(UTC)
Posts: 15,443
Location: DE-NW
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Originally Posted by: 5HorizonsRR I was looking at 2200uF 35v Cap as a good option, but not sure what a loco actually draws for power and if that will cover it? 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. Originally Posted by: Goofy DC motors don´t draw so much in power.
Märklins old AC and old 5 pole DC motor draws a lot! 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. |
Regards Tom --- "In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS  |
2 users liked this useful post by H0
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Joined: 16/02/2004(UTC)
Posts: 15,443
Location: DE-NW
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Originally Posted by: costing So my advise is to install the largest 25V cap that fits the equiment :) 25 V is not enough for items used in analogue operation (expect 40 V and more, so 35 V may also be insufficient). |
Regards Tom --- "In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS |
2 users liked this useful post by H0
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Joined: 20/08/2018(UTC) Posts: 157 Location: Geneve, Geneva
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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 :) |
JMRI on RPi & DCC++ / C-track / Marklin, Roco, ESU, Bemo locos / Christmas car collector |
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Joined: 16/02/2004(UTC)
Posts: 15,443
Location: DE-NW
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Originally Posted by: costing Glad I don't have any of that around and will thus keep everything well below 25V :) I just wanted to warn people that the 50 V capacitors are a better choice for items also used in analogue operation. 35 V capacitors are at risk. 25 V capacitors are theoretically sufficient for "digital only" operation with track voltages below 24 V. |
Regards Tom --- "In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS |
3 users liked this useful post by H0
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