guys i need your help here . please try to check where there problem might be. i i have developed an h-bridge using Darlington pair transistor (TP110) and i have try to turn on each transistor using a BJT that switches a 12V to each TP110.but my problem is that it just switches on itself with the bias of the transistor.

i have attached the design.

lihle

 

Well each darlington has 12V connected via a 1kΩ resistor to its base. It's not surprising they are on.

Also the drive BC107's will all hard short the 12V supply(s) at their collectors once they are switched on. Bye-bye BC107...???

Probably time to revisit the design. Where did you get this one?

Have a look here for instance ....http://www.solarbotics.net/library/circuits/driver_buf_h.html

 

Your design has multiple problems.

Try it like the attached instead.

 

Well each darlington has 12V connected via a 1kΩ resistor to its base. It's not surprising they are on.

Also the drive BC107's will all hard short the 12V supply(s) at their collectors once they are switched on. Bye-bye BC107...???

Probably time to revisit the design. Where did you get this one?

Have a look here for instance ....http://www.solarbotics.net/library/circuits/driver_buf_h.html

i did not get it from somewhere but i tried it on my own.

lihle