SlotForum banner
1 - 2 of 2 Posts

·
Rich Dumas
Joined
·
3,778 Posts
Most controllers have dynamic brakes which simply short out the motor when the brakes are on. Any time a DC motor is turning it generates a voltage, even when it is under power. The voltage is opposite in polarity to the applied voltage and is referred to as the back EMF. When the motor is unpowered, but still turning, shorting it out causes it to stop faster. In order to have dynamic brakes there must be current flowing through the motor windings so that they generate a magnetic field. Higher end controllers have a potentiometer in the brake circuit that can reduce the amount of brakes. Some controllers have MOSFET brakes. With that type of brakes you get full braking as soon as you back off on the trigger and the brake control lets you adjust how long the brakes stay on.
 

·
Rich Dumas
Joined
·
3,778 Posts
Shutting off the track power should have no effect on brakes. If the track has a power relay that is in the wrong place the brakes would not work when the power was off. I have tried several controllers that had MOSFET brakes and those feel different than ordinary dynamic brakes. The car will slow rapidly, then it seems to coast. 3rdEye controllers have that sort of brakes. Back in the mid '60s cars really wanted to coast, even with dynamic brakes. I wired up a battery and a variable resistor in the brake circuit and that worked well, however that scheme was outlawed before I could enter a single race. With PWM controllers it is possible for the cars to see a voltage that is higher than the track voltage and it is also possible to build one that applies reverse voltage braking. Some people view PWM controllers with considerable suspicion for that reason.
 
1 - 2 of 2 Posts
Top