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Dynamic Braking Question

2810 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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QUOTE (astro @ 21 Jun 2004, 23:32)... If you pull the trigger a little, you reach this point, and if you hold the trigger here a long time, the controller will heat up at its fastest rate, since the max voltage is being converted to heat)...
...not exactly, Astro.

First, voltage does not become heat. Only electric power becomes heat (another way of power). Starting from this point, maximum heat is dissipated in the controller when voltage and current reach maximum level. Ok, now let's suppose that our controller starts at the value of Ohms necessary to the motor just starts spinning and, logarithmically decreases its value up to zero as long as we press the trigger.
-Slower value means all the voltage in the controller but almost no current, so the power is almost zero.
-Fastesr position menas all the possible current but no voltage at all, so again the power is zero.
¿Where's the maximum dissipation? just in the middle position.

Coming back to reality, our controller does not control motor at starting spinning, but at a higher level (i.e., if we need 1,5v to start the motor, controller minimum position is 2,5v); and since we have a linear resistive controller(*), maximum power dissipation is around half the controller position.

Apologies for my english and this biblical text and for Astro, no aim to controversy.

(*) That's the answer to why you feel "very smooth" electronic controllers: they control voltage or current, resistive controllers are affected by load (motor).
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QUOTE (backMARKer @ 21 Jun 2004, 23:03)Oh ok.
Nuro, i dont suppose you know where i can get a wiring diagram to make a box with variable resistance control from on the net?


I don't have one at hand, but I'll search it tonight. Anyway it's very easy: just cut the brake wire and conect a 10 Ohm 2 Watt potentiometer in between. That's all.

Well, job is quite easy. Problem is the pot itself, it is hard to find, if you want it let me know.
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