user29882: 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...!!!

user3688: 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. 

29882: <p>First of all I'm a noob.</p>

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

<p>This is the design---> </p>

<p><a href="https://i.stack.imgur.com/sLr1I.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sLr1I.png" alt="DESIGN"></a></p>

<p>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 &amp; pin 10 respectively). </p>

<p>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.</p>

<p>Hence, I can control the direction of rotation of the motor.</p>

<p>BUT.....it wasn't working...!!!!</p>

<p>I need help...!!!</p>

<p>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.</p>

<p>So, again, please help me...!!!</p>
 3688: <p>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. </p>

<p>Normally you need both NPN and PNP transistors for an H-bridge:</p>

<p><a href="https://i.stack.imgur.com/YZC0A.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/YZC0A.png" alt="Basic H-Bridge Circuit"></a></p>

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

<p>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. </p>
