Using the polyphonic sound code from my electronic Dry Bones sprites along with the structural functionality of my illuminated mosaic Link portrait, I’ve combined both concepts. In this new portrait, I use a grid of flat LED panels fastened on to the rear door, with a 16 Ohm speaker attached as well. Controlling the whole circuit is a homemade circuit board with an Atmel ATmega328P as the central brain, containing an Arduino code for playing the music and activating the lights. The biggest technological feat for this project is how I successfully managed to control the 12V LED panels through a small 5.5V AVR, through the help of transistors. In layman’s terms, a small microcontroller like the ATmega328 is only capable of controlling circuits between 3-5.5V; anything else will burn out the chip. By using transistors attached to the digital outputs of the ATmega, I can control much larger loads, with the overall 12V input power being directed into the circuit via a voltage regulator. This new method allows me to control larger lights than simple LEDs, which opens new doors for potentially building more LEGO traffic lights and whatnot.
The physical LEGO portion was rather straightforward and didn’t have a lot of flaws. Towards the end of the construction, I had to slightly rebuild the project to use a small tactile button to activate the circuit. Originally I had a large momentary pushbutton installed near the bottom of the rear door: the button required too much pressure to push, which caused the structure to wobble and almost fall over when pressed. Creating the circuit board and wiring the Arduino code was also rather simple, since I used the same functionality of the Dry Bones model. Unfortunately, when I was testing out the method of using transistors for controlling the LED panels, I accidentally loaded the 12V power into my Arduino Uno’s 5.5V input — thus frying it. After purchasing a new Arduino, I successfully did some breadboard experiments with TIP120 transistors to control the LED panels. The LEGO structure opens like a book, and on the rear door are eight white SMD LED panels connected in parallel to three digital output pins of the ATmega — cathode to cathode, with the red positive wires being channeled into the positive terminal of the 12V power supply. For sound output, I created some makeshift speaker holes on the top right orange brick sprite: this was achieved by placing LEGO grille tiles over headlight pieces.