I want to get an email when mouvement is detected in my backyard. To have my whole backward covered with only one motion detector, I need to use one that comes with 120v outdoor lights.
To use this 120v output with my Arduino, I'll replace the 120vlightbulbs with a 5v cellphone charger. This 5 volts circuit will have a Led, resistor and a NC relay. When the motion detector will be triggered, the 5v relay will be energized, the contacts will close and the Arduino will receive a HIGH, then sending an email.
I checked the button tutorial since it is pretty the same thing, but I have one question left. In the tutorial, the button is pressed only a few seconds. The motion detector might output power for minutes. Do I need a load in the circuit that go from the 5v pin on Arduino to the relay contact to the input pin or is the digital input pin a "load" in itself (I'm worried about shortcut)?