Bi-Directional Motor Speed Controller V3
A bi directional motor speed controller kit. (RoHS Compliant)
Version 3
SPECIFICATIONS
Voltage: The kit and motor use the same power supply.
Since the maximum operating voltage of the LM324 is 18VDC then this is also the maximum voltage available to run the motor.
Current: The IRFZ44 MOSFET can handle 49A; the IRF4905 can handle 74A.
However the PCB tracks that
run from the MOSFET pins to the screw terminal block can only handle around 5A.
SPEED CONTROL OF DC MOTORS
Basically, there are three ways to vary the speed of DC motors:
1. With the use of mechanical gears to achieve the desired speed.
This method is generally beyond the
capability of most hobbyist home workshops.
2. Reducing the motor voltage with a series resistor.
However this is inefficient (energy wasted in resistor)and reduces torque.
The current drawn by the motor
increases as the load on the motor increases.
More current means a larger voltage drop across the series
resistor and therefore less voltage to the motor.
The motor now tries to draw even more current, resulting in the motor "stalling".
3. By applying the full supply voltage to the motor in bursts or pulses, eliminating the series dropping
effect.
This is called pulse width modulation (PWM)and is the method used in this kit.
Short pulses means the motor runs slowly; longer pulses make the motor
run faster.
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