How to slow a loco that is a LOT faster than all my others. Electronics experts help please!

ThomasDadDurham

ThomasDadDurham

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Im wanting my passing loops to use analogue automation, using RRConcepts Stationmaster system. The issue here is that two of my 5 locos are over twice as fast, if not three times as fast, as all the others (Diesel and Toby). They're all cleaned, and Ive asked other owners of the Thomas Large Scale Range and the consensus is - they are all radically different. That aligns with my opening them up. Same motors, but very different gearing, and age is also likely a factor with all of mine being 2nd hand, bar Diesel and Percy).

The alternating trains setups needs them roughly the same speed. At present, enough power to get James or Thomas up my incline with a train, means Toby or Diesel races round so fast they fly off on the first corner.

Ive been told 'add a string of diodes' as each diode gives a slight voltage drop. But I dread spending days soldering and unsoldering to try and dial in Diesel and Tobys speeds to match James/Thomas/Percy.

My question is, cant I add some sort of adjustable thing, some sort of speed controller, to the loco? Its confusing me because that would be like a second speed controller in line with the first (my controls are Gaugemaster GMC-10LGB's, fitted with PWM to Linear Converters from GScale Graphics as it was recommended to protect my locos which have soundcards.) and electronically, I have no idea what issues that would cause??

(Before the cries of 'go DCC', I really dont want to switch to DCC, because even then, I cant simply do 'alternating trains on a station stop passing loop', short of it seems, a degree in programming and making completely bespoke circuits. I just want an off-the-shelf solution hence the Stationmaster.)
 
Not sure but a DC - DC voltage buck ? Would put a top stop on the voltage a motor can receive and cap the loco's top speed. And they are easy to adjust so you get a desired voltage regulated speed cap. It would not slow how fast it got there though.

LGB used something on their track cleaning loco to slow it independent of the track power, used to rotate the cleaning heads at speed. I have seen some simple and cheap manual speed controllers that might do the job if interposed between motor and power supply. Something like this ESC-180 Max

EDIT - From what has been said by PhilliP neither of these are options as they cannot deal with polarity reversals. Oh well, back to the drawing board.
 
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I can't help you with the speed issue, but Curtis Roecks, the inventor/maker of RRconcepts Stationmaster, was extremely helpful when I was setting up my garden railway 35 years ago. I don't employ the Stationmaster since I converted to batter power about 15 years ago. I still have a handful of Stationmasters in my workshop.
 
All the speed controllers are going to be polarity sensitive, so fine if going forwards. - Many would release the magic-smoke if the controller was changed to reverse!

The diode string works in both directions, is quite simple, but you will need to set the speed control to the same setting each time. - There will not be a constant relationship in speed between different settings of the controller between the different models.

PhilP.
 
Madman said:
I can't help you with the speed issue, but Curtis Roecks, the inventor/maker of RRconcepts Stationmaster, was extremely helpful when I was setting up my garden railway 35 years ago. I don't employ the Stationmaster since I converted to batter power about 15 years ago. I still have a handful of Stationmasters in my workshop.
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Yes it was Curtis who offered the 'string of diodes' solution.


The speed difference is -extreme-. To get James pulling three coaches around, without stalling, I set the controller to say, 60-70 (GMC-10LGBs go from 0-100). If I then have him sharing the track with Diesel or Toby, at 60 they will shoot off like a bullet and bolt straight off the first corner they reach (Tobys roof is now chipped thanks to this), those two need to be set to 20-25 to go round at the same sort of speed - pulling a similar weight of train.

It means Toby and Diesel must always be paired on one track, and the other three are all close enough in speed to share a track. But my kids dont grasp this and demand to have whichever trains on whatever track they want, so I have to stand at the controls the whole time we play.

A device that would 'cap' the max speed and be adjustable so each train can be set differently would work - I'll need proper confirmation/second opinion that the 'buck converter' would work / wont cause complications?
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PhilP said:
[...]The diode string works in both directions, is quite simple, but you will need to set the speed control to the same setting each time. - There will not be a constant relationship in speed between different settings of the controller between the different models.
[...]
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The main controller on a alternating trains Stationmaster setup should stay fixed. The only reason I have to keep changing it at the moment is to stop fast trains flying off and slow trains stalling. I gathered I'd have to painstakingly adjust each and every train, adding a diode at a time, using the slowest in my collection as the baseline - this is what I was hoping to avoid (for time). I didnt think diodes would make them all the same speed on different settings of the main controller, if thats what you were getting at?

I just have absolutely zero time to fanny on with these things with two young boys. Its been a year and I STILL havent added the mylocosound cards to my trains, Ive only found time for one bit of soldering and that was a dud motor replacement!
 
Do you have a meter, so you can measure the voltage on the track?

Set a loco running, at the speed you want it. Then measure the voltage on the track.

Do this for all your loco's. You will then have an idea of how much you need to reduce the voltage by, in the loco's that are too fast.

Each diode in the 'string' will reduce the voltage by about 0.6V. So you can get the 'string' about right to start with.

Until you know the sort of voltage you need to reduce by, you can't decide if this is a viable solution for you.

PhilP.
 
Use the series diode method..... if you need more detail on what to do, you will need to figure out what voltage you need on the track to get the speed of movement you want from each of the too fast locos, then report back here.
 
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