In this guide I will show you how to build an OR gate with two transistors.
For a basic detail of how the NPN transistor is being used in this project, please see the intro message to my AND gate instructable.
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Step 1: Parts List
To build a logic OR gate you are going to need the following parts:
- 1x Breadboard
- 1x LED (Any color)
- 1x 1K Ohm resistor
- 2x 10K Ohm resistors
- 2x NPN Transistors (I used the 2N2222)
- 2x N.O. Push buttons
- 6x Various length wires/Jumper wires
You will also need to know how to build a circuit based off of a schematic.
Step 2: Schematic / Truth Table
First construct the circuit from the schematic in the above image. (Please excuse my terrible drawing skills..)
Now I will show you the truth table:
A B OUT 0 0 0 0 1 1 1 0 1 1 1 1
This logic gate is very simple, the output will only be ON (1) if A is ON (1), B is ON (1), or both are ON (1). Otherwise it will be OFF (0).