How can I connect H-Bridge motor driver (using four 2n222 transistors) to Arduino?

Question

First of all I'm a noob.

I was trying to do the H-Bridge using 2N2222 controlled by an Arduino Uno.

This is the design--->

I joined A1 and A2 to form a common terminal (say A), similarly, I joined B1 and B2 to form B. Now I connected A and B to 2 pins of the arduino (say pin 9 & pin 10 respectively).

So, theoretically, when I should digitalWrite pin 9 HIGH, then current should flow via A1 and A2, i.e. left to right in the motor AND when I should digitalWrite pin 10 HIGH, then current should flow via B1 and B2, i.e. right to left in the motor.

Hence, I can control the direction of rotation of the motor.

BUT.....it wasn't working...!!!!

I need help...!!!

After much thinking I had a hunch...."Perhaps, I am not giving GROUND to the transistors". I thought about it, but was unable to figure out the way of doing it.

So, again, please help me...!!!

Answer 1

I am not an electronics guru yet either so others might give you a better answer, but this is one circuit I have messed with a lot because I keep trying to build robots, so I will take a shot at an answer.

Normally you need both NPN and PNP transistors for an H-bridge:

The 2N222 is NPN so you'd want to pair two of them with two equivalent PNPs such as the 2N2907.

I've see diagrams that have all NPNs but I have never gotten a circuit to work that way. There is a distinction about where the load goes, before or after the transistor, that makes you chose to use an NPN or a PNP in order to make it all flow properly.