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Dynamic Braking Question

2821 Views 22 Replies 12 Participants Last post by  compound_goose
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When the slot car does dynamic breaking in what direction does the power attempt to travel? Does the power go the same direction as the current which came from the power supply OR does the power attempt to go the reverse direction? I would guess the reverse direction since there are brake light system which only light based upon the direction power travels through a diode?

Thanks VERY much!!

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The current generated by an electric motor while spinning, under power or not!! is reverse to the external power supplied. It is the motors efficiency as a generator which has marked effect on it's max revs. EMF generated will create its own magnetic field countering that of the supply until it eventually causes the motor to peak. ie it won't rev anymore. This is Lenz's Law

Lenz's Law states

"An induced electromotive force generates a current that induces a counter magnetic field that opposes the magnetic field generating the current."


When the controller brake is connected, on passive over run the emf generated is trying to cause the motor to run in reverse but it never will for as the motor tries to stall, so the reverse emf reduces.

Clear as day!

Also, as an alternative to having a pot as a variable brake control, I have eventually opted for a three position switch wired into the brake line, this introduces either a 10 or 20 ohm resistor into the brake line. It's more positive than a pot and is fairly knock and accidently adjusted proof. It works fine on thing like Ninco Go karts which end up braking side on! to taming some of the SCX 4WD Rally cars.

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If I forgot to thank you I sincerely apologize. Your response was on spot and appreciated.

I think I will go wire something up now!

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i think braking just whacks the 2 track terminals together, as there is no track power the car slows itself down due to the electricity being generated from the moter being reversed and put back through the motor, and so it goes on and on, rather then just relying on the friction generated by the car to stop

also wix, could you stick a circuit diagram of ur controller mod in
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