PiBot Help!!!

Other Hardware General Electronics
1

For a project for university i an making a PiBot! The robot itself is powered by the arduino which is run by a rasp pi setup as a webserver. the website in which it is hosting will provide the input for the arduino.

My Problem, I made an error when designing the PiBot. The bot has two motors rated for 4.5v -15v, and im using 4 NPN transistors (2n 3904) to provide a h-bridge to control the motors direction. I am using a 9v battery to power the motors but want to control the h bridge using the arduino. However i believe the arduino is not man enough to provide the current i need to switch the transistors. I havent got long till this assignment is due so i need a solution. I spent a lot on this already in both time and money and really dont want to get new motors. I have thought about using relays but again i dont know if the arduino is man enough?

2

An arduino output pin is powerful enough for a 2N3904 base current, with 10 mA it will easily saturate.
Question is rather if the transistor is powerful enough for your motor.

Rather an Ampere than a Volts question.

3

Firstly the 2N3904 is completely unsuitable for driving motors, its absolute
maximum collector current is 0.2A. Most small motors take 1A or more, but
since you haven't told us which motors you have I'm not able to suggest
replacements.

4 NPN transistors cannot make an H-bridge unless you are using bootstrapped
supply to drive the high-side transistor bases. Are you tied to 9V supply (small
9V motors are unsuitable for powering motors).

What circuit are you using?