Relay and mains load

Goal

Switch a power load safely from a pin.

Why it matters

The relay galvanically isolates the control side from the power side.

Steps

1. 01Add a relay module on pin 7.
2. 02Declare the pin as OUTPUT.
3. 03Switch every 3 s and print the state on the serial port.
4. 04Note that a flyback diode protects the driving transistor.

Next tutorials

• PWM: dimming an LED

  Breathe an LED from 0 to 255 with analogWrite().

• Potentiometer → brightness

  Set LED brightness with the knob (10 bits to 8 bits).

• RGB LED: mixing colours

  Create any colour with three PWM channels.

• Smooth fade (sine curve)

  Make the fade look linear by using a non-linear curve.