well, i posted about an h-bridge befoe, finally i made it work very good.
actually my very first (didnt post it here) circuit worked fine , the problem is that i gut some 2n3904 transistors and half of them was bad. right from the store and they are bad !!.
after filtering what is good and whats bad, everything worked fine
thanks to all of you for your previous help.
now i am trying to feed the circuit with a PWM
as i am using PIC16F628A , which have 1 pwm channle and can only be outputed to one exact pin.
so i thought of 2 things
1. to take the pwm output pin and feed it to another pin, then redirect the signal to other pin , but i am afriad something can go wrong in timing, beside i will tie up the pic in that job and i will lose the benfit of build in PWM.
2. to put a nand gate IC (4011) to do the job (attached picture), so i gave it a try .
the motor runs very strangly and it is obvios that i have 2 states , FWD and RWD, so i have to power the ic from another pic pin.
anyway i need to hear your ideas and thougts about the second solution or anyother solution that i maybe missing here.
PS ( i cant use a dedicated PWM ic)
thanks a lot