The 5v Relay Arduino Awards: The Best, Worst, And Weirdest Things We've Seen
https://www.evernote.com/shard/s511/sh/84013a30-80d9-5c8b-49a4-39839a76ba84/8b2e40fdce1a089abbc063fc4b788d56
With this program you might learn how to use relay modules. If the input variable (excitation) becomes a specified need, the relay is really a part where the quantity of demand of your output circuit takes place