11) relays
TRANSCRIPT
Electromagnet
• A coil of conducting wire wrapped around a piece of metal
• Example: Copper winding around an iron nail
• Pass current through any conductor and it generates a magnetic field
• Provide supply at two ends of coil and it starts attracting iron pieces
Inside Relay
• A coil with two supply terminals and a SPDT Switch with terminals: COM, NO and NC
• COM: Common, NO: Normally Open and NC: Normally Close
• No supply: COM and NC are connected
No supply given to coil
• Disconnect supply: COM and NC gets reconnected
• Lever comes back due to an internal spring
Relay is connected across two halves (lower & upper) of BB
All legs of relay should be inserted in different columns
Note: Please look at next slide before you start
Connect Relay on BB
Providing supply to relay
• Every Relay needs a certain voltage to activate
• Relay in the kit will activate at a voltage ≥ 12V
• To make ≥ 12V, connect two batteries in series
• When supply is connected, relay gets activated and produces a click sound
• Click Sound: Lever shifts from NC terminal to NO terminal
Giving supply to relay
Wrong Connection Right Connection
Note: In case of wrong connection, relay is not connected to Vcc