I want to control my motor using pwm (Arduino), I was going to use scr controller but as its shipment is delayed I am thinking of canceling it. Now my question is can pwm can reduce the rpm say 4900 to just 40 or below. I really need to slow this motor down to this much value as I have salvaged it from a treadmill. second question is that will it effect the torque? . everyone saying don't use scr, and as I have studied it is cheap but very noisy and need to use firing angle to control which is more like a rough way of controlling a motor.

MOTOR specs : permanent magnet DC motor
1.5 HP @ 100VDC
14 amps
4900 RPM

 

also there is a problem with the resolution I.e 0-255 , this Is the range in which you can control the speed of dc motor

 

Hello,

You already have a thread for this:
converting threadmill motor of 100VDC to use for my project at lower rpm and high torque

Bertus