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I made an interactive coffee table that turns led lights on under an object, when the object is placed over the table. Only the leds that are under that object will light up. It does this by effectively using proximity sensors, and when the proximity sensor senses that an object is close enough, it will light up a node underneath that object. It also uses an Arduino to put on animations that don’t need the proximity sensors, but add a really cool effect that I just love.

The proximity sensors are made up of photodiodes and IR emitters. The emitters use infrared light (which the human eye cannot see) to shine light up out of the table, and the photodiodes receive the infrared light reflected off an object. The more light that is reflected (the closer the object), the more the voltage fluctuates coming from the photodiodes. This is used as an indicator to tell which node to light up. The nodes are a collection of ws2812b leds and a proximity sensor.

The attached video goes over the entire build process, while I outline more of the details below.

ws2812b LED Bulbs
5V Power Supply
Any Arduino I used the 2560
IR Emitters
10 Ohms Resistors
1 MOhms Resistors
47 pF capacitors
CD4051B Multiplexers
SN74HC595 Shift Registers
ULN2803A Darlington Arrays
Any substrate to use as a large board for the leds, I used a paper composite board from home depot”

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