hi all,

i have 2 questions about this circuit that i took from this page :
http://www.precisionmicrodrives.com...discrete-driver-circuits-for-vibration-motors


if i read this circuit correctly , i see that it drives a vibrator motor (of a cellular phone) with a PWM signal and a dc voltage , so my question is , why the PWM signal cannot drive the motor itself ? it's because it doesn't have anough current to drive the motor ? and my second question is, why is it wrong to drive the motor just with the dc voltage (without a pwm signal) ?

thank !

 

a lot of those motors are burshless motors, and will not work on dc alone.

 

The PWM allows you to control the speed/intensity of the motor. And since PWM is usually a "signal level" used to switch a "power level" voltage it may not be a high enough level to run the motor.