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Offline shunter  
#1 Posted : 06 August 2012 17:20:57(UTC)

Joined: 12/02/2005(UTC)
Posts: 90
I am wandering what the use/purpose of the choke coil are in the pic supplied with the motor conversion packs.

I have some locs that have them attached in the wiring to the motor and some without them ,
and i notice no differance when running them around the track .

Anyone who can give me the dummy explanation BigGrin

When the world is running down, you make the best of what's still around.
Offline H0  
#2 Posted : 06 August 2012 17:47:16(UTC)

Joined: 16/02/2004(UTC)
Posts: 12,196
Some say they prevent radio and TV disturbances, others say they protect the decoder.

I think all my Märklin locos with 5-pole HEP have them installed and I always add them when I do digital conversions.
AFAIK most locos will run without them without problems. I never tried it without them.

Analogue Märklin locos and digital locos with AC/DC motor had one choke of a different type installed.
"How can I see what I'm leaving for / How can I give what I gave before / How can you tell me that you want me to stay
How can I stay when I'm trying to say / That I can live without the rain / Yes I can live without the rain" (Rick Parfitt)
Offline intruder  
#3 Posted : 06 August 2012 18:16:58(UTC)

Joined: 16/08/2006(UTC)
Posts: 5,532
Location: Akershus, Norway
They have been a part of all Märklin 5-pole conversion sets since the first 6090 set.

As far as I know, they are installed in all digital locos from Märklin with the 5-pole high power motor.
I do as Tom and always install them. Märklin could save a lot of money not installing them, so they are there for a reason.
Best regards Svein, Norway
grumpy old sod
Offline shunter  
#4 Posted : 06 August 2012 19:33:03(UTC)

Joined: 12/02/2005(UTC)
Posts: 90
I was curious for the reason because as said i found 2 of my loco's that don't have them and run perfectly.
Both done by official dealer.
As i took the plunge and give it a try myself to convert some locs i noticed them missing
and wandered about the purpuse of the part.
Won't take any risk and just use them in my conversions .
When the world is running down, you make the best of what's still around.
Offline Webmaster  
#5 Posted : 06 August 2012 20:12:11(UTC)

Joined: 25/07/2001(UTC)
Posts: 10,715
I'm in the group "protect the decoder" from voltage spikes due to derailing and such myself... BigGrin
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
Offline RayF  
#6 Posted : 06 August 2012 20:36:05(UTC)

Joined: 14/03/2005(UTC)
Posts: 14,288
Location: Gibraltar, Europe
Chokes, or inductors, attenuate high frequencies. They let DC pass straight through, but prevent sharp voltage/current spikes from getting through.

In the context of a motor, high frequency spikes are generated by sparking at the commutator. These high frequencies can have two negative effects.

The first effect is that if they are allowed to conduct down a length of cable they will use the cable as an antenna, and radiate these high frequencies as radio waves. These waves will interfere with TV and radio reception in the vicinity of the trains.

The second negative effect is that the voltage spikes, which can have quite a high amplitude, will feed back into the output stages of the decoder driving the motor. They can be enough to damage the output stages and maybe blow an output transistor within the decoder.

Inserting the chokes in series with the motor brush connections will go a long way towards both preventing unwanted Radio emissions from your layout and also protecting your decoders from voltage spikes.


Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
thanks 1 user liked this useful post by RayF
Offline Bigdaddynz  
#7 Posted : 06 August 2012 20:36:26(UTC)

New Zealand   
Joined: 17/09/2006(UTC)
Posts: 15,778
Location: New Zealand
This has been discussed in the forum previously, but as Tom and Ray point out they are there to prevent radio and TV interference, and to protect the decoder.

Best to use them, even though a conversion may seem to work fine without them.
thanks 1 user liked this useful post by Bigdaddynz
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