How to Make a NOT Gate Circuit with Transistor

NOT gate also name as inverter.

It changes from 1 to 0 and 0 to 1.

We can make NOT gate circuit with one transistor.

Very simple and work with digital signal.

It uses very less parts.

Output is opposite of input and it works fast.

It is useful in digital circuit, computer, electronic project.

Easy to learn and can be build at home.

It can also be used for logic operation and signal control.

Truth Table for NOT Gate:

The truth table is the main table used for a NOT gate:

The above table shows:

NOT gate give opposite output.

When input 0 then output 1.

When input is 1 then output 0.

It always invert the signal

Symbol of NOT Gate:

Circuit Working:

Parts List:

Above circuit diagram uses NPN transistor.

Input go to transistor base through resistor R3.

If input is HIGH to 5V then transistor is ON.

Then output become LOW to 0V.

If input is LOW to 0V then transistor is OFF.

Then output become HIGH to 5V.

And LED show output state.

Formulas:

Below is the general formulas for NOT Gate Circuit with Transistor:

To calculate base current:

Ib = (Vin – Vbe) / R3

where,

• Vin is input voltage of (5V)
• Vbe is 0.7V

To calculate collector current:

Ic = (Vcc – Vce(sat)) / R2

where,

• Vcc is 5V
• Vce(sat) is 0.2V

How to Build:

To build a NOT Gate Circuit with Transistor follow the below steps:

• Take all the parts as shown in circuit diagram.
• Transistor base connects via resistor R3 to input
• Transistor Collector connects via R2 to +5V power supply.
• Transistor Emitter connect to ground of the circuit.
• Connect resistor R1 between the junction of emitter, Gnd and cathode of LED1
• And anode of LED1 goes to INPUT
• Connect anode of LED2 between collector of transistor and resistor R2
• And cathode of LED2 connect to GND

Conclusion:

This NOT Gate Circuit with Transistor is simple and easy to build.

It can be used in logic circuits to invert signals.

LED shows output state.

It is good for learning basic digital electronics.

References:

Building NOT gate with transistor — output remains always high