# Home build throttle



## Michael W (Oct 10, 2012)

This is the second go of building a throttle....
After the first one worked out I decided to give a pwm controller a go ... I used a kemo m171 controller that can handle up to 10 am ( given it has a good heat sink) I just finished the first trial run with my piko BR 80 loco... The loco starts very smooth and runs great, smoke works even on low speed settings reasonable well. ( I am running a massoth 18 v smoke unit).
the only thing that puzzeled me was the fact that on low speed settings the lights on both ends are on, on "pure DC" they were strictly directional with the odd flicker. My question now is is the pwm interferingwith the electronic in the locomotive or can I just ignore the lights?
I did not notice the locomotive becoming hot or otherwise misbehaving despite pulling 10 cars for about 30 minutes on various speed settings.
Also do I have to put smoke fluid in the chimmney ( the smoke unit is constanly on) or should i wire a switch into the smoke circuit?
Kind regards Michael


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## Dan Pierce (Jan 2, 2008)

Check the smoke unit specs, some can be left on without fluid (LGB) and some need to be shut off (older Aristocraft.USA trains). Newer Aristo units do have a shutdown circuit for low/no fluid. 
When in doubt, turning them off is best.


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## Greg Elmassian (Jan 3, 2008)

There is probably a regulator or other circuit for the lights that may be getting confused by the pwm. This definitely happens in Aristos, since their regulator is often a microprocessor, and it goes nuts under 5 volts. 

I agree, add a switch, even if the unit has an auto shutoff. 

Greg


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## Michael W (Oct 10, 2012)

Thank you very much for the feedback, I shall put a switch in it just requires minor surgery... I also take the loco apart on the weekend and add a couple of diodes this might fix the light issue as they are leds... Never mind i now put a BIG heatsink intonit so I can run up to 10 amp ...
Kind regards michael


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## Greg Elmassian (Jan 3, 2008)

A suggestion, a small "computer type" fan will make a huge difference in cooling... I mean the small ones like QSI provides for their 10 amp decoders, like about 1-1/4" square... just a little airflow makes a lot of difference. 

See how hot it runs and also I have no clue what your "environment" is , hot, cold, enclosed box, etc. 

Greg


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## Michael W (Oct 10, 2012)

This is a good idea, I got several computer ones leftover for the main power supplies... 
I did yest the throttle today with my br 80 smoke 12 carriges for about an hour and it works great, I am quite impressed with this little loco the throttle does not even get warm at this stage, the manufacturer recommends a heatsink when its used above 5 amp, my power supply is limited to 5 amp at this stage so once i need more amps i will start tinkering again, but next is track and rolling stock... 
Kind regards michael


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## Greg Elmassian (Jan 3, 2008)

Glad to see that it is working fine... ideally, a small 24v fan running at 12 volts would be nice and quiet and give just enough cooling for max loads... enjoy! 

Greg


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