24 switch pixel



24 standard light switches control the color of a single pixel. Using light switches and analog electronic circuitry, this piece simulates the binary logic a computer uses to control the red, green and blue color values of every pixel on a computer display.

With 24 switch pixel, bits are blown up to human scale and reveal an accessible view and opportunity to interact with the hidden language and logic behind a single pixel.

Materials: Acrylic, Light switches, Resistors, RGB LED.

view of back

*** Technical Description and Documentation ***

Construction & Additional Images

This piece uses analog electronics to model a 24-bit color digital display pixel. The circuit is built using standard light switches, a ton of different resistors and one RGB LED.

Each switch is connected in series to a set of different value resistors. When closed, the switch’s resistance is added to the circuit. When open, its resistance is removed from the circuit.

If we move from left to right, the switches are divided into 3 sets of 8. The first 8 control the red pin on the LED, the second the green and finally the blue.

For each color channel, the switches further to the left are the more significant switches because they are connected to the highest resistor values. When the switch is open they remove the most resistance from the circuit and allow the most current to flow. When it is closed they introduce the most resistance into the circuit and allow less current to flow. As we move to the right, the switches have a lower resistance and therefore have a less significant impact on the overall current flow.

If we count down 8 bits in binary from left to right, we have values of 128, 64, 32, 16, 8, 4, 2 and 1. The resister values decrease corresponding to these values. The switches furthest to the right have a virtually negligible effect on the circuit. When you turn them on and off, the current change is so slight that you can’t even see a change in the LED. This is the same as on your computer display. Pixels with the RGB value of (1 ,2 ,1) look black.

When all of the switches are off, the maximum resistance is applied to the circuit and the LED cannot receive current. This is a black pixel with an RGB value of (0,0,0). When all of the switches are on, we have maximum current on all channels. This is a white pixel with an RGB value of (255,255,255).

More about the binary numeral system.
More about 24-bit color and color depth.
More about resistor ladders.