Hello everybody. In this Instructable I'll show you how to make easily a contactless switch with a distance sensor. It might be very useful for your house or other machines.

Because I'm a student and I'm making a project about 'Passive house' and I want to have a special switch.

Step 1: What You Need

What you need to make

this switch, are:

-wires

-a breadboard

-a distance sensor. I prefer the HC-SR04 or a HC-SR05.

-an Arduino board

-an LED to test the program

Step 2: Wiring

The distance sensor has 4 pins:

-VCC

-TRIG

-ECHO

-GND

Connect:

-VCC to 5V pin on your arduino board

-TRIG to a digital pin (in my case pin 3)

-ECHO to another digital pin (in my case pin 4)

-GND to GND

Connect the LED to a digital pin, it has to be different from the other pins.

Step 3: Program

For some of you who don't understand the code, there are two parts (in 'void loop') in my code:

-The first part is about the distance sensor. To measure the distance, the sensor sends and receives echo (kind of sound). I've used the length of an A4 sheet (29.7 cm - 11.69") to calibrate it. In this calculation "distance = (duration / 2) / 29.7", I've divided the duration in 2 because the time that the echo needs to go from this side of the sheet to another side of the same sheet, is the same as the echo goes from another side to the sensor (it is placed at this side of the sheet).

-The second part is the main part of this code. This is the structure of my code:

While(...){

...;

While(...){

...;

While(...){

...;

While(...){

...;

}

If your hand (or an object) is between 2 and 10 cm (0.79"-3.94", you can change this range in the program), the program will enter the first "While" and the LED (or something else) will turn on. And when you move your hand further than 10 cm (the 2nd "While"), the LED still have to turn on (like a normal switch). If your hand is between 2 and 10 cm for the 2nd time (3rd "While"), the LED has to turn off. And when you move it away from the sensor (>10 cm, 4th "While"), the LED still have to turn off until you move your hand closer than 10 cm again.