How would you set up a circuit to obtain NOT gate using a transistor?
Hint: The transistor should have only one input and one output.
Step 1: Find the configuration of the transistor equivalent to a NOT gate.
The NOT gate is a device which has only one input and one output i.e., means Y equals NOT A.
This gate cannot be realised by using diodes. However it can be realised by making use of a transistor. This can be seen in the figure given below.
Here, the base B of the transistor is connected to the input A through a resistance Rb and the emitter E is earthed. The collector is connected to 5 V battery. The output Y is the voltage at C w.r.t. earth.
The resistor Rb and Rc are so chosen that if the emitter-base junction is unbiased, the transistor is in cut off mode and if emitter-base junction is forward biased by 5V, the transistor is in saturation state.
