H-Bridge for Motor Control - Will this work??

[Birdman Adam]

Hey I just thought this circuit up for a blind-opener project. I didn't have any H-bridge ICs at hand or PNP transistors, so I made this with only NPN transistors. I was hoping someone could tell me whether this would work at all, and if it could, if I have the protection diodes in the right places to protect from back-emf to the transistors (or MCU). I was thinking of using 2N2222A transistors, because the motor is very small, (less than 400mA). Just forget about the resistors, b/c I forgot to change them to the correct values... Any help would be greatly appreciated. Thanks!

**broken link removed**

 

[BrownOut]

You should get motion with this. Just remember, the power dissapated in the transistors is dependent of current AND voltage. Consider that when choosing the transistor.

 

[smanches]

You will need to increase the voltage to the high side transistor base's to get them to turn on fully. This is because of the voltage loss going through the load.

Other than that, it looks like a pretty standard h-bridge.

 

[Birdman Adam]

OK, great, I should be able to work with this then... Now what about the diodes? Have I positioned them so as to prevent any EMF damage? Thanks.

 

[smanches]

Yes, the diodes are fine.

 

[Birdman Adam]

Great! Thanks for all the help.