how would i build a circiut using NPN transistor making the result of OR gate??

[faria shah]

i cant get when will the base will be get open or short to conduct through emitter???help plzzzzz

 

[faria shah]

yes plzzzz help me out

 

[Grossel]

Just add two sets of a diode and resistor in series/parallell to the base. This will act as a NOR gate, so you have to put a inverting stage (another bjt NPN + resistor) to get an OR gate.

There is other alternative ways to achieve a OR gate just by PNP's and diodes

yes plzzzz help me out

I just did. You don't have to point it out, it's a waste of time.