Hi all,

In my search for ways to improve the ANALOGUE running of my Märklin locomotives, I´m looking for cheap/easy solutions.
What I need to improve is the SLOW running, or "torque" at low tension of the good old 3-pole analogue locos.

I would like opinions on this suggestion;


This would maintain the old mechanical direction control, but substitute the AC field coil with an HAMO/ESU permanent magnet.
2 diodes and some rewiring is also needed, but still I would say it is simpler and cheaper than a high-performance motor upgrade with decoder et al. -JUST for being able to run properly in analogue!

I dont know the force of the permanent magnet, but ASSUMING that 16Vac over the field coil is the equivalent, I would think something like this;

Original Märklin;
Control-knob (Trafo, 16Vac)__AC-Field Coil___Anker___Power
100% (16Vac)_______________100%__________100%____100%
50%________________________50%___________50%_____50%
20%________________________20%___________20%_____20%

My suggestion;
Control-knob (Trafo, 16Vac)__Magnet________Anker___Power
100% (16Vac)_______________100%___________50%_____75%
50%_______________________100%___________25%_____68%
20%_______________________100%___________10%_____55%

I realize that the above tables are not electrically nor physically correct, but it seems to me like there would be relatively more "power" present at the lower voltages¿?

The reason why I ask here in the forum instead of just TRYING it, is because I dont have a permanent magnet at my disposal. Before rushing out to buy some, I would like an opinion...


-Also, I am playing with the idea of changing the 3-pole anker to 5-pole one; In that case I can use the old 5* current-hungry anker and the HAMO magnet, OR (even better but more expensive) the modern 5-pole high-efficiency ankers with their magnets.

So, what do you think. Am I dreaming???

Edited by user 25 October 2023 13:21:41(UTC)  | Reason: Not specified

Hi Henrik
Your proposed schematics is strange.
You complain about old Märklin locos being slow when may I have were way too fast.

Just a matter of opinion:
- in analogue AC I would do nothing, In analogue DC, adding diodes on the inductor coils (to allow remote direction change) should NOT slow down significantly your loco (06 V versus a typical 10 V operation voltage.
- in digital you have 2 choices (A) keep the coiled field inductor and use a dedicated decoder 60906 (MFX, DCC, MM2-capable with 6 outputs for lights etc. (B) replace the motor (inductor and rotor) by a HDLA motor and using a mLD3 or mSD3 decoder giving additionally full motor regulation but having the drawback of higher cost and removing parts on a sometimes valuable historic piece of a collection.

I made some tries just like you did on an old 3015 / CCS800 (a flea-market find) to use a left-over C90 decoder and 2 Schottky diodes (very low drop-voltage), one for each coil winding.
The results were it worked OK but the in-series motor provides a low torque so probably, replacing the inductor by a magnet is a good idea

Connecting directly the rotor like you propose with regular head-tail diodes provide a voltage drop of 0.6 volt which means a serious increase in current at Märklin voltages, but probably OK at typical DC voltages (6 to 10 VDC).


Cheers
Jean

Hi Henrik

I like your tinkering spirit!
Not really sure if your idea would work. I understand what you are going for, but you basically turned the AC motor into a DC motor by adding the permanent magnet. I have a loose gear train out of a lok were i changed the coil and replaced it with a permanent magnet but kept the 3 pole rotor laying around, works fine feeding DC in it, but honestly never tried running it with AC.
To reverse direction, you need to change the polarity on the brushes of the motor, as far as I know the original mechanical relay can not do that.... but not sure on that...

Regards
Jean-Pierre