Question

Consider two npn transistors as shown in the figure . If 0 Volts corresponds to false and 5 Volts corresponds to true , then the output at C corresponds to

Answer 1

@Mashy , Could you please help me out ? :)

Answer 2

What is the input at A and B? :O

Answer 3

We need to put in all combinations of 0 and 1 in it and then see the output

Answer 4

I'll attach the solution , I was not able to understand the solution at all !

Answer 5

Ok.. ok.. so basically you have to figure out.. what logic gate the transistors make

Answer 6

Could you tell me how i can infer which gate ?

Answer 7

The transistors are basically switches.

when you give a signal to the base, imagine that the collector and emitter get connected.

in our case, the emitter is grounded, and the collector is connected to the output. Also you can see that Output is connected to a high potential
If both transistors are off (0, 0 condition), the the output remains high at 5V (so o/p = 1)

if you switch of any of the transistors, immediately the o/p is pulled down to zero
can u see that?

Answer 8

The problem is telling you to use positive TTL logic, where +5 volts is true or (1) and 0 volts (ground or very close to ground) is false or a 0.

The inputs are connected the base of two npn transistors that are connected in parallel with exception of the inputs. A positive voltage or a "true" level applied to their base will turn them on if either one of them or both of them are turned on then the output will be false or 0. So to get a 1 or true output at C you will have to have them both turned off at the same time. The circuit acts as a NOR circuit (Not Or) logic gate.

Answer 9

a NOR gate is