Martin:

Nice to see another member on this forum from the bay area. First, with regard to your questions concerning decoder conversions, I have done several and have used the ESU Lokpilot V4 decoder. I am not sure if the two locomotives you mentioned have field coils but I am guessing they do. If that is the case you would need to replace the decoder and the field coil with a permanent magnet. So you can do a conversion for a little less than $50 per engine and I have really enjoyed the quality of the decoder and the running of my 3pole motors with these chips. (I don't replace the motor with a 5 pole motor and thus don't have to change the face plate either).

With regard to your question on layout size and boosters, it would depend on what your power source is. Are you using a Marklin or ESU control unit? Or have you bought one yet? I can't speak to the Marklin units but I know with my ESU 50200 I would say you don't need any booster with only 5 trains running. I am not sure how many Amps the Marklin CS sends to the track but that will be what guides the number of boosters needed. The size or number of pieces of track you use don't have an impact on number of boosters because you can always run feeder wires from your power source to all parts of your layout to make sure you don't have power drop.

Chris

Hi, Martin,
you don't need motor parts for your 37185, only a new decoder (this is generally the case for 37xx and 37xxx locos).

Check if the locos have standard decoders. Many Märklin steamers have special decoders that also contain e.g. tender lights (shouldn't be a problem with the 33081, but probably with 37185).

Since your lights are going to be on a different line you are left with what consumes the most which are locomotives and point motors. You might have many points but in reality they will not be all switchng at the same time so that should not be a great concern. Unless you run some old train that was not very well designed -we had a client with an ICE train which had a Delta decoder and that one was terrible-I would say 5 good trains should run fine. If they have interior lighting I suggest you use LED's it will make a great difference.

I haven't used a Marklin station in a long time but the later model probably has like the ESU an indication of how much power is being consumed so that should tell you how close you are from the limit. Having boosters can be a good way to separate different lines with their own power supply and that way when there is a problem it is also easier to find it

Make sure not to join the power from the CS to your independent transformer for lights or you may blow up the station.

Martin:

My guess is you will be fine. I have not had a power issue yet running trains. Good luck.

Chris