This was an interesting puzzle, it used a feather duster with magnets inside to activate magnetic reed switches hidden inside the plaster lion statue. People are given clues as to how to dust the old lion statue in order to activate it. Upon activation a laser shines out from its mouth and points to the next puzzle or clue in the room.
The mechanism behind this is pretty straightforward, an arduino nano monitors 4 inputs to see if they get pulled high by 4 magnetic reed switches, and records the state, if the right combination is entered the eyes light up green, and the laser is activated for 20 seconds.
The eyes are initially turned off so that that statue doesn’t stand out, but once the first input is correctly activated the eyes flash green once to indicate that a correct input has been detected, and then remain red awaiting the next input. The eyes flash green on each correct input, but upon an incorrect input they turn off, and the sequence must be repeated from the beginning.
The reed switches were simply embedded into cutouts that I made with a rotary burr into the plaster statue. You can see one on the nose, one on each front paw, and one on the back which is in the next picture.
These are just standard magnetic reed switches that you can get from jaycar or aliexpress.
They were simply covered over once installed and checked for reliability using acrylic cap filler, and textured to match the surroundings. I also drilled out the pupils of the eyes for the fitting of 3mm bicolour LEDs.
The reed switches in the front paws covered up really nicely too.
Inside the circuitry was very straight forward, just a series of pull down resistors for the digital inputs on the arduino which if you’ve seen any of my other projects, I just solder onto the back of the arduino board. The bicolour LEDs each run off two pins on the arduino, and the colour change is achieved by pulling one pin high with the other pin low, and reversing this to swap colours from red to green, it’s all super simple. The laser diode just runs directly of an output pin.
