Diode logic gates use diodes to perform OR and AND logic functions as shown in the circuit diagram. Connection of the LED at the output is optional which simply displays the logical state of the output, i.e. the logic state of output is 0 or 1, if LED is off or on, respectively.

How does the diode act as a logic gate?

Diode Logic OR gate (wired OR connection)

If one or both inputs are at logic “1” (5 volts), the current will flow through one or both diodes. This current passes through the resistor and causes the appearance of a voltage across its terminals, thereby obtaining logic “1” on the output.

Is diode A NOT gate?

The NOT gate can be easily understood by using a LED (light emitted Diode) circuit. This is also called Light switch circuit. In this circuit, NOT gate functions like an electronic switch.