by zeke » Mon Nov 16, 2020 2:54 am
If you want to change the speed of a DC motor, you can do it a couple ways. If you lower the voltage from what it was designed for, it will lower the speed but have reduced torque. A better way is with pulse width modulation (PWM).
Instead of feeding the motor a straight DC voltage, PWM sends a series of full voltage pulses. The pulse width is variable from zero to full width, effectively turning the motor on / off several times a second thereby controlling the speed.
For those who don't know, an oscilloscope displays voltage on the Y axis and time on the X axis
Most new cars use PWM fan controllers for efficiency and reduced noise.
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