1/2 H Bridge power & ground

charlieknox

Using a BS2 on a BOE, I am trying to duplicate the 1/2 H Bridge circuit shown at

http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/bjt_analysis.html

I'm puzzled as to where the ground symbol on the top left optoisolator output transistor emitter hooks to.· Does it hook to the BOE Vss, or TP4, Battery Negative, or both?· By the same token, does the V+ on the collector of the optoisolator lower transistor go to Vdd, TP1 Battery Positive, or both?· For that matter, does this circuit need a common ground, or a common V+?· Can't be both, I don't think the Stamp would appreciate that with a 12 volt battery for the motor.· I'm new to using both an NPN and a PNP in the same circuit, so a bit confused as to what will work here, and not release any smoke.

Thanks for any help or insight you can give me on this one.

Charlie

·

Phil Pilgrim (PhiPi)

Battery negative. To maintain isolation, it should not be connected to Stamp Vss. By the same token, V+ would go to battery positive.

-Phil