NOT Logic Gate – Digital Signal Inverter

The NOT gate is the only logic gate with just one input. It has a digital (high or low) output that is the opposite (inverted) of the input.

7414 74HC14 hex inverting schmitt trigger integrated circuit schematic symbol truth table pin layout diagram by electronzap
7414 74HC14 hex inverting schmitt trigger integrated circuit schematic symbol truth table pin layout diagram by electronzap

For demonstration circuits, I like to use a blue LED that is wired to light when the output is low, and a red LED that lights up when the output is high.

A trimpot (trimmer potentiometer), wired as a voltage divider, has a wiper terminal that can output any voltage between what is across the 2 end terminals of the resistive element.

Turning the trimpot most of the way to the positive supply (close to 5V) is a high input. That will set the output low (close to 0V). Which means that the blue LED will light up, because it is between +5V and close to 0V at the output.

On the other hand, by turning the trimpot close to 0V ground, the input gets a low input signal from the trimpot. That means that the output will go high (close to +5V). In that case, the red LED lights up because now it is the one between +5V at the output, and 0V (ground).


There are 6 (hex) Schmitt Trigger NOT logic gates in the 7414 integrated circuit. The 74HC14 is the high speed CMOS version of the 7414. High Speed CMOS is the most common version of 7400 series integrated circuits.

I recommend getting at least one 74HCxx kit to practice building circuits with. I have two 74HCxx kits because I fried about 6 of the ICs from one kit. The 7400 ICs fry a bit easy from the static discharge of your body or accidental miswiring. It’s a good idea to buy about 5 to 10 of the specific ones that you think you will use a lot to make prototype circuits.

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