AVR project log H-bridge 2

17/10/09 Day 33

This is a follow up from the previous post.
As stated in the previous post, while connected to a 9v power supply, and controlling the H-bridge with 5 V, the motor only had a poor 3.6v across it!!

Mine very own H-bridge design, which turned out to be not functional.

After doing some simple analyzing with a multimeter ( I should have done this earlier!! ) and found out who "stole" the motor's voltage. My finding are as below.
** note: Q1 and Q2 below are the circled in the 1st diagram.

drawn with multisim 10

So all the voltage was across 1st transistor emitter and collector!!!The only part I got the H-bridge working was that the 2 transistors of each side (top and bottom) are turned on in reverse state, thus preventing short circuit.
However this H-bridge, had lead me to discover one thing--- I have poor knowledge in transistor!!!

The following H-bridge is a design from pocketmagic , and it works well ( should be, now just trying with 5V power, need to get a 9v regulator to really test it out)

I've also found another H-bridge design from one of my senior final year project report, but I never tested it out. I'll just place it here for future reference.