Material: Elegoo Uno starter kit (compatible with Arduino)
Mono white LED strip
The best thing about the Arduino tool is that it is an open source community. You learn, experiment and exchange on platforms like Github and the Arduino portal itself. Arduino is a tiny circuit board, easy to use for beginners in electronics and coding.
A Capacitive sensor is made of an output (send pin) that transmits a pulse, and an input (receive pin) which receives the pulse and compares it to the transmitted pulse.
I will tell my Arduino to read the transmitted pulse so that above a certain number (calibration) it will trigger something (in this case LEDs).
The advantages are it is cheap as capacitive sensors can be made out of any conductive material (I use conductive paint) and can be used as invisible switches. On the downside, they are unstable and need calibration.
I first created basic prototypes with only LED’s and an Arduino. This first one is made of 10 coloured LEDs connected through an Arduino to a graphic symbol drawn with conductive paint.
This prototype allowed me to find out how much resistance I needed (10MegaOhms minimum) to have a stable capacitive sensor. That the size of the sensor matters. We can see in the video (below) the capacitive sensor is very sensitive and react event if my hand it an inch away, it is also sensitive to pressure.
The second prototype is the base of the final project. I programmed two capacitive sensors to trigger 3 or 4 different LEDs.
In the figure above, the right sensor will trigger the yellow LED on the right and the left sensor will trigger the yellow LED on the left. If both sensors are touched at the same time the red and the blue LED light up with the yellow ones.
The code used for this prototype can be seen here:
Here is a picture of how I wired the transistors to make the white LEDs work.
I replace the single LEDs from the second prototype with white LEDs and NeoPixels. NeoPixels are addressable LEDs, this means I can program which colour they will be and which one lights up at what time on an LED strip. They are relatively easy to use with the Adafruit library or FastLED library. They can be used to create small animations.
On the video, you can see that pieces are placed on the board, but the game (LEDs) could actually be activated without it as capacitive sensors can be trigger by human touch. All I did it increase the resistance so that my capacitive sensors are more sensitive and can recognize human touch through the 3mm thick acrylic pieces.