I have a 3 rail Atlas GP15 (MoPac) and it runs too fast. I was lurking in the 2RS forum and someone mentioned the "Williams trick" of rewiring motors in series. What is this technique and can it be done to slow this Atlas engine down, while maintaining TMCC control - perhaps so it runs closer to the speed of a switcher?
Thanks...gregg
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Get a bridge rectifier, tie the "+" and "-" leads together. Find the leads to the motors, cut one and wire the "~" leads on the rectifier into the break. This will drop the voltage by about 1.5 volts to the motors.
The series trick can be used if there's no cruise control. There's a diagram on the thread somewhere that's better than I can describe, but the only caveat is that if one motor loses traction, the other will sit doing nothing like a regular differential on a car in a mud hole.
Thanks! What size/type of bridge rectifier would I need?
...gregg
If your engine already has TMCC but no cruise control why not install the ERR Cruse Commander?
You can get a full bridge rectifier from radio shack number 276-1181 8amp connect the + to - lead then cut one motor lead into and connect one side of the cut lead to the ~ and the other side to the other~. Just like Matt said or you can use Dale H way it works just as well.
A bridge rectifier is really 4 diodes in a package connected in a certain way. When the + and - are connected the remaining 2 leads become 2 diodes in 1 direction and 2 diodes in the other direction.
If the bridge rectifier is used as a DC voltage dropper,which it is in this case,only half of it conducts current at a time. In effect it only then has half it's rating. So an 8 amp bridge would be good for 4 amps. This is probably enough for most cases. The voltage drop would be about 1.2 volts per bridge.
Dale H
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