I'm trying to build one of those mini sumo robot's as a project and I have a working drive circuit. I'm trying to control it with my parallel port on my computer that way I can write control programs and change behaviour relatively easily however my circuit has quite a few losses and I was wondering if anyone had any advice for it. The values for all the components are just estmates because I don't have the actual motor yet and the multimeters in the circuit are the "motors" while I was using a program to digitally test it. From what I can tell the motors I want to use have a resistance of 6 ohms when stopped and can handle a maximum voltage of 8.4 volts safely. ( I was trying to get the car to run around on 6v and then have the option to boost at an additional 3v that makes 9 which is slightly over the maximum for the motor but will only be for short times.) (all the logic pins at the bottom and the ground are the PP interface). Thank for any help.