Why BC327 explode in this Hbridge design?

[buddace]

The problem is that when the BC237 are off ....
whit BC337 switch on ... BC327 explode
Test runs without any load connected to the outputs ..... piloting half bridge at a time.
Where the hell not??

 

[FvM]

Re: Hbridge problem

BC327 explode

Not surprizing. It's given by the design of this strange circuit.

Calculate the node voltages and transistor bases currents and see why.
I guess you hope, the PNP transistor would fully switch off while the NPN is on, but it doesn't.

 

[buddace]

Re: Hbridge problem

BC327 explode

Not surprizing. It's given by the design of this strange circuit.

Calculate the node voltages and transistor bases currents and see why.
I guess you hope, the PNP transistor would fully switch off while the NPN is on, but it doesn't.

Thanks for answer..any idea to resolve ?