To fix this I wanted to build an H-bridge to put in-between each motor and the NXT.
The output signal from the NXT is 9 volts which I want to use as the PWM signal
The motors require a 12 volts source which I want to connect to a wall outlet for a steady power supply.
Sometime ago, I had this schematic supplied to me and I simplified it a bit. I was told that I should calculate the resistor values myself but as I don't know how the formula goes I just went and got some 1k and 10k resistors.
I put all the stuff on a breadboard and nothing worked. Measuring where the power was didnt' help. I think the transistors might not be working as I'm sure I connected them the right way around.
I did however put a + on input 1 and a - on input 2 and later I found out that transistors don't like negative voltage or something.
This was because I want to not only go forwards but also backwards with the motors. The PWM signal just inverts the + and - signal. I do not know how to achieve this, but I thought maybe adding some diodes to make the power run in only one direction, but then again I don't know where I would put them if I also needed to ground the setup and since ground changes the wire it runs in when the motor is running the other way, I just don't know.
TL;DR Need help making a PWM controller for a motor that will run both ways using the same input for forwards and backwards.
