This distinctive variation of a Christmas tree is made from a thin printed circuit board, which is cut in the shape of a spiral. This is then stretched out to create the shape of a Christmas tree. There are 25 white LEDs on the spiral, which are driven by a pseudo- random number generator.

Christmas trees come in various types and sizes, even electronic ones. Over the course of the years we have published a fair number of electronic variants in Elektor. Somebody in the Elektor Labs recently had the bright idea to design a spiral Christmas tree, made with a thin PCB. The PCB is stretched upwards, creating a shape similar to a Christmas tree. A set of (white) LEDs is mounted on the spiral. The onboard electronics ensures that the LEDs flash in a random pattern. To keep things as simple as possible, we haven’t used a microcontroller. Instead, an ‘old-fashioned’ circuit using digital logic has been applied. This consists of a simple random number generator (built around a 4015 dual 4-bit static shift register and a 4070 quad XOR gate) and a number of FETs for driving the LEDs.