Help 12 volt DC motor brake!!

Discussion in 'The Projects Forum' started by toxic_sea_monkey, Mar 5, 2009.

  1. toxic_sea_monkey

    Thread Starter New Member

    Mar 5, 2009
    I have a linear actuator that i am using to lower a spade for grooming ski trails. It works great but the problem i am having is that it travels too far each time i turn it on. It overruns the desired depth due to the momentum of the motors rotation.

    I am hoping that there is a good way to install a resistive network or somthing that will act to slow the motor each time the power is switched off. I know this could be done with a simple resistor and diode in paralell to the motor, however the motor is switched to run in both directions (reversing the polarity).

    Another potential solution i thought of was just installing another switch that would control the motor through a resistor to lower the voltage. This should slow the motor and be used as a fine adjust although i would just like to install a brake circuit.

    Any ideas?
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    You could treat it like an H-bridge driver does smaller motors, where "Stop" removes power, then shorts the two motor leads together, using it's the motor's own EMF force to stop it spinning quickly. Make sure your switch can handle the current, and that power is also disconnected by another pole of the switch to prevent a meltdown.
  3. mik3

    Senior Member

    Feb 4, 2008
    You can use a switch to short the motor's armature windings and slow the motor down due to the current produced by the induced EMF. However, make sure the motor can handle this short circuit current because if the inertia of the motor shaft and the load is large a large current will flow for a significant time interval.
  4. b.shahvir

    Active Member

    Jan 6, 2009
    you can modify the wiring to incorporate a power dissipating resistance to soften the mechanical or electrical stresses which might be encountered during dynamic braking of the DC motor........ as mentioned above.