June 21, 2010:
Revised: v2.0

ZL2PD Electronic Christmas Tree

Brighten up the ham shack at Christmas with this electronic Christmas tree. Adapted from a design originally published in Elektor magazine in December 2007, this design features an improved PCB and some component changes for better performance.


Christmas time is usually the time for festive decorations including the traditional tree. I am usually the one who gets to purchase the tree, and with varying degrees of help, get it home in the car. The most demanding task is getting the tree standing properly in the right place in the house. But, once this is completed, the rest of the family join in to decorate the tree, adding all sorts of colourful decorations, along with traditional tinsel and sparkling lights. Most years, we also have a model train and carriages going around the base of the tree on a short loop of track to add to the overall effect.

Why should the ZL2PD ham shack be any different? I came across an interesting design for an electronic Christmas tree in Elektor magazine a few years ago. It described a colourful LED design but suggested building the circuit on a very boring triangular shaped PCB.

I have a computer controlled milling machine which I use to make some of my PCBs. This machine opens up a number of options when it comes to making PCBs in unusual shapes like this. Why not make it more like the shape of a real Christmas tree?

So, while it was too late to build the circuit for that Christmas, I had time to make a few changes to the schematic, to design the new PCB I had in mind with the help of some drawing software for the tree outline, and to mill out the required PCB. It was all ready in time for the next festive season.

For those interested in a different kind of Christmas tree, perhaps for those in tiny apartments without the space for even the smallest Christmas tree, this PCB design may be the answer.

The Design

A series of LEDs are connected to selected outputs of a CMOS CD4060 binary counter. The 4060 also has an internal oscillator which is set by R1, R2 and C1. Output Q4 is a square wave of twice the frequency of that on output Q5. In turn, this is twice the frequency on Q6.

The 4060 drives the various LEDs directly from six selected output pins.  Selecting six different outputs from the 14-stage binary counter inside the 4060, three of which are the slowest output frequencies,  results in a semi-random blinking of the LEDs. The PCB layout is also arranged such that the LEDs are placed to maximize this near-random light pattern.

The CMOS output stages deliver constant current to the outputs. The current is highly dependent on supply voltage. This inherent current limiting allows the LEDs to be directly connected to these outputs without the need for additional current limiting resistors.

The only disadvantage of this method is that the LEDs are very bright when the battery is fresh, but this brilliance steadily falls over the subsequent weeks of use. However, the LEDs will still blink happily even when the battery is down to the last few volts of life. Amazing.

Note: The IC used in this circuit is a standard CMOS CD4060. Do NOT attempt to use a 74HC4060 or 74HCT4060 device in this circuit. 


The PCB I designed lies at the heart of this design. In my prototype, it stands about 100mm high. Without access to a CNC milling machine, you will have to make the PCB using a small hacksaw and a file. With care, it’s possible to do, but it will take a bit of time.

I purchased a variety of different coloured high-efficiency LEDs from my local parts supplier. The suggested layout is shown opposite. I managed to find bright blue, green, red and yellow LEDs, and the arrangement I used is shown in the diagram at the top of the page. My supplier had some incredibly bright blue LEDs, and one of those looked great at the very top of the tree where the star is usually placed on the full size version.

These LEDs allowed me to power the circuit from a 9V battery for several hours on most evenings over the three weeks in December leading up to Christmas Day. The LEDs are really bright for the first two weeks, but they gradually dim over the following weeks, and the pace of the LED flashing slows down, but the battery does last for ages.

I didn’t bother adding a power switch to the board. Something of an oversight, perhaps, but the battery lasts for so long, it’s almost unnecessary. I just plug in the battery when needed.


PCB layout: GIF format (43kB file)

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