PWM problems

[jacks]

Hi Friends

My H-bridge is working but I tried using a function generator and its not changing the speed of the motor. I connected one strobe to a high(5V) and the other strobe to the function generator in order to vary the pulse. I built the second circuit on the diagram below. I did not connect the function generator to the input of the circuit because I felt it will turn on and off the cycle.
Thanks

Jacks

 

[Roff]

I don't know if this is related to your problem, but the way you are doing your strobe will, as a minimum, screw up your input offset voltage, maybe worse. The recommended circuit is shown below.

 

[jacks]

Roff

Thanks for your reply. So does it mean that the transistor acts as a strobe? On the base of the transistor, how much current should I input?What is it connect to? Thanks

Jacks

 

[Roff]

Roff

Thanks for your reply. So does it mean that the transistor acts as a strobe? On the base of the transistor, how much current should I input?What is it connect to? Thanks

Jacks

When the base is below 0.5V, the comparator will be operate normally. When the base is between 3V an 5V, the comparator will be disabled, and the output transistor will be off. For voltages between 0.5V and 3V, the state of the comparator is indeterminate.