h-bridge please help

i got this of the net
would this h-bridge work with a/b at 6v and v+ at 12v

monkeytree said:

i got this of the net
would this h-bridge work with a/b at 6v and v+ at 12v

Click to expand...

Not properly, the inputs need to go to the positive rail to work properly (and preferably higher!), and even then it's not a very good design, the top transistors should really be PNP, not NPN, to give good switching.

Also it is misiing the free-wheel diodes across all the transistors to provide a free-wheel path for the machine current.

And to stress what Nigel said you need higher base driver voltage (to ensure BJT's are saturated - they wouldn't with such a voltage).

use FET's if the input is a problem

This look better for me...