How to control DC motor (only speed) using PWM ?

[zelsenussi]

how can i control dc motor only(speed) using pwm ???????i know how can i generated from pic 18f but how could it efect the speed of dc motor ??plz in details
thanks in advance...

 

[ramysk]

Re: pwm

you can control the motor speed by controlling the average of the input voltage(dc component), and this is exactly what you are doing through the PWM. as you can control the average of the PWM signal by controlling the PWM duty cycle.
increasing the PWM duty cycle means that you increase the average of the input voltage hence increasing of the motor speed and vice verse.