How to Use a Diode in a Circuit

Think of a diode as a one-way electronic valve for electricity. When the diode is in forward bias, the diode allows current to flow towards the cathode leg. In a reverse bias current is blocked so there is no flow of electricity through the circuit.

Difficulty: Moderate

Instructions

1. Place the diode in your circuit so the cathode leg is in the direction you want current to flow. Look for the dark band on the diode. It is located on the side of the cathode terminal. For light emitting diodes (LEDs) the cathode leg is the shorter leg or the leg that is located on the notched or flat side of the LED.

2. Design the circuit with enough voltage to pass through the diode. You will typically need at least 0.6v to pass through the one way valve (diode). If not enough voltage is supplied the one-way electronic valve will not allow current to flow. Look at the specifications of the type of diode you want to use. Using too great of a voltage (either positive or negative voltage) can damage the diode.

3. Choose the type of diode you want to use in the circuit.
   
   Choose a zener diode if you need to have a voltage sensitive switch in your circuit. The available voltage breakdown range is from 2 volts to 200 volts.
   
   Choose a small signal diode to perform logic, protect circuits, or transform low current AC to DC voltage.
   
   Choose a photodiode to create a circuit with light detection.
   
   Choose a light emitting diode (LED) to add light to your project.
   
   Choose a power rectifying diode to transform higher current AC to DC.

Tips & Warnings

• Use extreme caution with working will electricity to prevent injury or fire.

[lighthouse1958]

on 10/30/2009 Described doing this very good, thanks for sharing. 5*

[sonni57]

on 10/28/2009 Good article on using diodes in a circuit.