1. Hello there. Smiley, Smasher, and myself will be assisting you as we learn how to wire a mechanical relay circuit. When you are finished with this lesson you will be able to draw and wire a relay circuit. 1 Dr. Gary Stewardson, Raymond Boyles

2. Relays In this lesson we will be discussing relays. The type of relay that we will be working with is known as a mechanical relay. A relay is simply a switch that is controlled by electricity. There are many types of relays as shown below. The relay we will work with is identified by the red arrow. 2 Dr. Gary Stewardson, Raymond Boyles

3. Relays Hello, Shorty again. In your first lesson, light a light bulb, you learned how to draw the schematic for the circuit. The light bulb used in this circuit is referred to as a load. 3 Dr. Gary Stewardson, Raymond Boyles

4. Relays If you were to replace the light bulb (load) with a coil of wire (load) we can created an electromagnet. 4 Dr. Gary Stewardson, Raymond Boyles

5. Relays The electromagnet is similar to a regular magnet. Question: What is the main difference between a regular magnet and an electromagnet? Hint: Look at the switch on the electromagnet. 5 Dr. Gary Stewardson, Raymond Boyles

6. Relays That’s right! You can turn off the magnetism with the electromagnet! 6 Dr. Gary Stewardson, Raymond Boyles

7. Relays We can use this magnetism to create an electric switch. With this circuit and a switch we can create a relay. A relay is nothing more than an electric switch. 7 Dr. Gary Stewardson, Raymond Boyles

8. Relays Smasher and Smiley here. Remember when we were testing continuity? Here is the schematic representation of that circuit. 8 Dr. Gary Stewardson, Raymond Boyles

9. Relays Notice the symbol for a buzzer. 9 Dr. Gary Stewardson, Raymond Boyles

10. Relays When we placed a conductor across the two terminals the buzzer would make a sound. 10 Dr. Gary Stewardson, Raymond Boyles

11. Relays The same reaction can occur with our electromagnet. We call this electrical switch a relay 11 Dr. Gary Stewardson, Raymond Boyles

12. Relays Now we can draw the flow of electricity in both circuits. The solid red arrows show the flow of electricity in one loop and the red and blue arrows show the flow of electricity in the second loop. 12 Dr. Gary Stewardson, Raymond Boyles

13. Relays We can control the 1.5 Volts in the top circuit with the 12 Volts in the relay circuit. 13 Dr. Gary Stewardson, Raymond Boyles

14. Relays Now that we understand how a mechanical relay works in a circuit let us complete Activity 8: Wire a Mechanical Relay 14 Dr. Gary Stewardson, Raymond Boyles