A blinking LED Christmas tree


A rainy afternoon just before Christmas 2011, I decided to make a construction for fun and decoration. This is a Christmas tree made out of carton and LEDs. I have also included a circuit to make the LEDs alternatively blinking, thus making a nice effect.

Making this blinking Christmas tree may be fun to do with your kids or people that you love. It is not difficult to make, although it takes up some time. I made this within an afternoon.

The first step is to collect all the necessary materials. A piece of carton from an old container, a marker, a cutter and a needle is all that is needed. Of course some LEDs, a few resistors and capacitors and some transistors for the electrical circuit as well.

Draw a tree on the carton and use the cutter to cut it. Take care with the cutter, you are doing it for fun, you do not want to cut your finger.

After your tree has been cut, use a needle and make holes on the carton tree for the leads of the LEDs. Then insert the LEDs as shown in the photo.

Calculate the positions of the LEDs onto the tree based on the number of LEDs you have available. Try to use a multiple of the 6 LEDs in total, for example 12, or 18, or 24 etc.

The finished tree should look like this. The back side is full of LED leads and it contains the electronic circuit. A hot silicon or glue can be used to keep all these in place, if you need to make your tree portable.

The electronic circuit is fully transistorized, as I did not want to use microchips. It is composed of a multi-vibrator that drives a pair of transistors, which in turn drive the LEDs. It can operate in a variety of voltages. As you go up in voltage the LEDs get brighter.

Each side of the LEDs blinks for about 1/4 sec. If you need other timing, change the 4.7k resistors in the multi-vibrator. The bigger the resistors, the greater the time. For example two 15k ones, will make the LEDs blink for about 1 sec.

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