I am working on making a remote controle tank using a infrared transmiter and reciever i can make it go forward and turn but i dont know how to make a hbridge so it can go backwards to. and im not sure what transistors to use or in what configeration.
A list of transistors and schematic would be greatly appreciated
Well, since chips like the L293D allow you to provide a separate voltage supply for the motors, you can try it at a lower voltage and see how it works. Since the outputs on these chips typically drop about 1.5V from the Vs supply anyway, if you provide 3V in you will get about 1.5V out.
Or, you can provide 5V in on Vs (the motor supply) and getting about 3.5V out. Then use some power diodes in series to drop the voltage down to an acceptable level for the motors.
Or you could run the motors at 3.5V through the chip with 5V being supplied at Vs as described above, but use PWM so they do not run at full duty cycle.