One heartwarming trend in recent years within the maker community has been electronic art such as a freeform circuits and PCB art. These projects rarely have a practical purpose, which gives makers the opportunity to design devices that exist only to satisfy their own need for creative expression. They also make very nice gifts for friends and loved ones who don’t necessarily care about how some gizmo works. That was the motivation for Andrew’s LED Tree, which can be blown out like a dandelion despite lacking sensors or even a microcontroller.
This piece of artistic engineering was heavily inspired by a project that made the rounds back in 2018. That project featured a single LED that could be “blown out” like a candle. It was special because no sensors were used to detect the user blowing. The only components were an Arduino Uno board, a single conventional LED, and a resistor. It worked because the voltage drop of diodes, including LEDs, will vary based on their temperature. When someone blows on an LED, the temperature is lowered and the voltage drop will change by a few millivolts. That change can be measured by a microcontroller and used to turn off the LED, making it look like the user is blowing it out.
Andrew’s LED tree relies on the same principle, but is special for three reasons: it looks beautiful, it has many LEDs that can be blown out individually, and it doesn’t use a microcontroller. In place of a microcontroller, Andrew is using a multitude of analog components. Those include discrete components and ICs (Integrated Circuits). The LEDs are soldered at the end of copper wire that is twisted to form a tree trunk and branches.
The LEDs at the end of every branch can be blown out individually, and Andrew even added a game. To win the game, the user has to blow out all of the LEDs within a short period of time, like trying to blow all of the seeds off of a dandelion in a single breath. If they do, a red LED at the base will flash as a reward. The base is made from custom PCBs with 3D-printed stand-offs. We can only hope that the recipient of this gift appreciates how much work Andrew put into building it!