Introduction: Diode Logic Gates - AND & OR

In this Instructable we will build DRL circuits. Diode-Resistor Logic

Diodes can perform switching and digital logic operations. Forward and reverse bias switch a diode between the low and high impedance states, respectively.So that it may serve as a switch.

Logic Diodes can perform digital logic functions: AND, and OR. Diode logic was used in early digital computers. It only finds limited application today. Sometimes it is convenient to fashion a single logic gate from a few diodes.

10-15 minute project!

Step 1: Parts

Picture of Parts

These are the parts needed:

Leds

Diodes (generic)

Resistors (680 Ohm-1K) recommended

Jumpers

9V Battery

Step 2: Building the Circuits

Picture of Building the Circuits

First we will build the AND gate.

  1. Place a 2 position dip switch on the bread board.
  2. Connect one side (both pins) of the switch to ground.
  3. The opposite end of the switch will connect the two diodes (cathode).
  4. The positive end of the diode are connected in series.
  5. Create a node or junctions to connect the resistor and the led as pictured.
  6. Connect the free end of the resistor to 9V. Ground the free end of the led.

Now let's build the OR gate.

  1. Place a 2 position dip switch on the bread board.
  2. Connect one side (both pins) of the switch to 9V.
  3. The opposite end of the switch will connect the two diodes (anode).
  4. Connect the cathode ends with a jumper if needed.
  5. Create a junction for the resistor and led from one of the diodes cathode end.
  6. Ground the led and the resistor.

Troubleshoot:

Make sure diodes are in the correct positions. The line on the diode represents negative. (cathode) Also check your leds, be sure they are not backwards. Does your circuit have power? Are the outputs in the correct location? Finally check for faulty parts.

Step 3: Test Your Circuit

Picture of Test Your Circuit

Give your circuit a try. Use the dip switches to toggle between high and low states to see the circuits outcome. If you are not familiar with the truth tables for these logic gates just give the internet a quick search.

FYI: Led will turn on under digital logic conditions.

Step 4: Support

Picture of Support

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Bio: I enjoy creating 3D models of pcb circuits. I am a student studying Electrical Engineering. I will share some cool projects & try out a few. More »
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