Continuing with our Growduino project we go over what relays are and why we need them and begin the basics of coding your Arduino so you can remotely access or schedule automation!

Relays!
* A relay is a switch that is toggled electrically
** It gives us the ability to turn on and off a circuit with a different circuit
-- So a 120AC circuit could toggle a 12V DC circuit
-- A 5V circuit could toggle a 24V circuit

There are several different TYPES of Relays
-- Electromagnetic (the most popular)
-- Optomechanical (Much like EM, but the circuits are COMPLETELY isolated from each other)
-- Solid State (No moving parts. All switching is done in a semiconductor)

We're going to be using electromagnetic Relays
* In the most basic version: a switch is toggled between "on" and "off" by an electromagnetic that physically moves the switch between the two positions

uxcell HH54P D 12V Coil Relay ~$8
-- They can be normally open or normally closed, some, like the UXCELL can throw multiple circuits simul

For our projects, we can use something a little more simple

Uxcell 12V 5-pin Mini Power Relay ~$7
* The side of the relay with three pins
-- The OUTSIDE pins power the electro magnet
-- The INSIDE pin is the NO/NC pin that links to the other side of the relay
* The side of the relay with two pins
-- One is the normally open pin
-- One is the normally closed pin

The important part is that we can use a 5-volt circuit to toggle a circuit up to 30v (or 120v AC)

Demo 1:
* Relay that is toggled by a simple switch

Demo 2:
* Relay that is toggled by an Arduino

Code for today's project is found here.

Hosts: Fr. Robert Ballecer, SJ and Bryan Burnett

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