# Varying speed, automatically?



## Cap'nBill (Dec 27, 2008)

I have a reversing unit (Miniatronics RU1-1). Problem is the speed .....I think,.....needs to be set quite slow as there is an abrupt change in track polarity when changing direction. I'm afraid any faster speeds would be deadly on gears! Is there something out there that would automatically allow fast speed on a main line, slowing before reversing? I guess blocks could be used, but guess that means multiple power supplies with varying settings. Any thoughts? Bill


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## jimtyp (Jan 2, 2008)

Bill, you might see if this site has anything that might help you. They have both DCC and DC components to do a lot of things. 

Click on the DC Analog tab:  Bitswitch


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## Polaris1 (Jan 22, 2010)

A MTH Fly wheel on the motor shaft IF there is room..??


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## toddalin (Jan 4, 2008)

You can us a "slowing section" (or sections) just before the stop as I do.

Your stop track has a diode in it with an insulator. On the section of track just before that, add an insulator and jump it with a) a resistor (5+ watts, ~4-8 ohms will work), b) an inrush thermistor(s) (some are rated at 2.5 ohms and some at 5 ohms and both will provide a "gentler" start-up, especially two 2.5 ohm thermistors in series), c) a couple diodes placed in series with each diode resulting in a ~0.7 volt drop, or d) some combination thereof.


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## irskir (Sep 13, 2008)

Hi Bill, If you train goes off the end into a diode section then it should stop before reversing. (assuming this is a back-and-forth operation) There would not be an abrupt change in polarity but just an on/off sort of thing. 
Take a look at this hookup but replace "YardMaster" with your Miniatronics unit: (you just need the diodes) 
http://www.rr-concepts.com/YardMaster/yardmaster_reversing.shtml 
A slow-down, speed up reversing could be done with a StationMaster/Reverser but this would take the place of your Minatronics reverser so you probably don't want to go this way. I'm just throwing it out there since it's another way to do this with the slow down you were looking for. http://www.rr-concepts.com/documents/SmReverserAp.pdf 
Have fun, Curtis


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## kormsen (Oct 27, 2009)

Bill, 
i am just implementing that at the moment. slowing down my trains before the stops in passing sidings. 
the simplest way i found, was to connect the powerpack to the track outside of the passing siding, using one foot sections of track and isolating one rail between each section. this isolatins i bridge with a diode each. 
as each diode "eats" 0.7 volts and the further the train goes into the siding, the more diodes are between the train and the power, it slows down gradually. 

if you want your trains to be able to back up, you would need two diodes in different direction at every railgap.


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## Dan Pierce (Jan 2, 2008)

Use a dcc decoder in the engine and reversing DC polarity will not reverse the engine, the engine slows down and reverses by user programming. LGB even had a register for stop delay before reversing. See CV 58.


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## Cap'nBill (Dec 27, 2008)

Thanks for the ideas Guys! It appears the Stationmaster/reverser is the best 'Off the shelf' solution...hadn't seen that before. I like the rather simplistic approach with the diodes, etc. I did find another DIY site with some possibilities for a kind of controller. I started out in Large Scale as a 'logger', a simple back and forth slow moving Shay/Climax combo, thus the Miniatronics unit. Then one day I got the 'sickness' and bought a heavyweight......that lead to a diesel A unit. Then I needed a B unit, then I needed a larger transformer.....................and so, the disease began to spread. I fear it's terminal! I don't know if there's any medication out there, I've tried Jack Daniels, but alas, to no avail. But as you can see, a passenger train has to have some speed....and slow down for the station!


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## toddalin (Jan 4, 2008)

Posted By Cap'nBill on 20 Aug 2011 08:17 AM 
Thanks for the ideas Guys! It appears the Stationmaster/reverser is the best 'Off the shelf' solution...hadn't seen that before. I like the rather simplistic approach with the diodes, etc. I did find another DIY site with some possibilities for a kind of controller. I started out in Large Scale as a 'logger', a simple back and forth slow moving Shay/Climax combo, thus the Miniatronics unit. Then one day I got the 'sickness' and bought a heavyweight......that lead to a diesel A unit. Then I needed a B unit, then I needed a larger transformer.....................and so, the disease began to spread. I fear it's terminal! I don't know if there's any medication out there, I've tried Jack Daniels, but alas, to no avail. But as you can see, a passenger train has to have some speed....and slow down for the station!


Using powered A and B units with a reverser is *TYPICALLY* a no no unless the two engines are wired together to share pick-ups. Otherwise, when the first engine enters the reversing section it stops and the second engine tries to push it through. A "smart" _electronic_ reversing unit may get around this.


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## Cap'nBill (Dec 27, 2008)

Hadn't thought about the MU issue! Guess I'll have to think some more on this, though re-wiring an AB unit shouldn't be too difficult. Bill


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## irskir (Sep 13, 2008)

Hi Bill, the StationMaster/Reverser does not have the diode isolated sections at the ends so it doesn't matter if you double head, connected or not. It will decelerate and accelerate the entire length of track. I think this would be the electronic solution mentioned previously. Sounds like fun!


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