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Question Permanent magnet with AC-motors?
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Offline hxmiesa  
#1 Posted : 25 October 2023 10:00:31(UTC)
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hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 3,594
Location: Spain
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;
DC-schaltung.gif

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! Unsure

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

Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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Offline marklinist5999  
#2 Posted : 25 October 2023 13:33:28(UTC)
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marklinist5999

United States   
Joined: 10/02/2021(UTC)
Posts: 3,908
Location: Michigan, Troy
Other factors can affect draw. Line load variations, double heading loco's, for example.
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Offline JohnjeanB  
#3 Posted : 25 October 2023 13:43:59(UTC)
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JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,563
Location: Paris, France
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
My layout videos
latest vid
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My Layout
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thanks 1 user liked this useful post by JohnjeanB
Offline hxmiesa  
#4 Posted : 25 October 2023 14:36:32(UTC)
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hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 3,594
Location: Spain
Originally Posted by: JohnjeanB Go to Quoted Post
Your proposed schematics is strange.
You complain about old Märklin locos being slow when may I have were way too fast.

Hi JohnJean,

I need the locos to run slower. They are indeed too fast.
Quote:
What I need to improve is the SLOW running, or "torque" at low tension


I am sorry if my schematic is not clear;
What I want is for the locos to be able to drive SLOWLY, with as little a voltage as possible.
I also want to maintain the old direction reverse-relay, so with a permanent magnet, the only way to change the direction, is by using diodes. -But of course this cuts away half of the AC power.
The diodes I use drops the voltage with about 0,7V. -In any case I think the lowest output of a Märklin trafo is around 6V.
The whole idea is to AVOID having to use decoders for analogue running.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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Offline cintrans  
#5 Posted : 26 October 2023 01:40:12(UTC)
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cintrans

Aruba   
Joined: 11/07/2018(UTC)
Posts: 217
Location: Aruba (general), Oranjestad
Originally Posted by: hxmiesa Go to Quoted Post
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;
DC-schaltung.gif

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! Unsure

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???


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
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Offline hxmiesa  
#6 Posted : 26 October 2023 08:25:15(UTC)
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hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 3,594
Location: Spain
Originally Posted by: cintrans Go to Quoted Post

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...

Thanks for your comment.
Well, the diodes will feed the negative _OR_ the positive part of the AC-wave to the anker, letting the train run in different directions depending on the position of the mechanical reversing relay.

The motor would definetly RUN, but my doubt is what its characteristics will be like.
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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WWW
thanks 1 user liked this useful post by hxmiesa
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