Introduction: A Simple Blinking X-mas Tree

About: I'm a 15y.o. electronic hobyist known from Instagram as EEPblog. I enjoy every bits and pieces that are under the subject of electronics.

Hi there!

This is my first instructable and i hope it'll be understandable :D

So today I'll show you, how to make this simple blinking X-mas tree based on the 555 timer. It's really simple, which means it's good for beginners in electronics, and also if you just so happen to take out something on your way bulding this, than there shouldn't be any worries too, as every component in this build is inexpensive and really common, so don't be afraid to experiment!

So let's get in to it!

Step 1: Tools We're Going to Use:


  • Hot melt glue gun
  • Wire-cutters
  • Pliers
  • Soldering iron (with solder of course)


  • Helping hands
  • Soldering flux
  • Breadboard for testing

Step 2: Parts and Materials:


  • 1N4007 diode
  • NE555 (8DIL socket is optional)
  • 6,8k resistor
  • 5,1k resistor
  • 2x 1k resistor
  • 10k resistor
  • 2x BC547 transistor (alternatively 2N2222)
  • 100uF capacitor (the voltage rating doesn't really matter)
  • 2x AA Batteries (Holder recommended) or
  • A Power brick, the voltage rating should be between 3.3V and 12V, current at least 100mA
  • A good amount of LEDs (I got mine off of ebay)
  • Appropriate resistors for your LEDs (more about this is further in this instructable)


  • Perf board (I'm used to perf boards, but you may prefer building your circuit on Strip board)
  • Cheap Xmas tree from pound land / dollar store
  • Couple meters of thin wire
  • Few zip ties to manage the wires

Step 3: Testing

This step is optional. If you have the courage, you can skip this step!

So let's finally begin! Firstly we'll wire it up on a Breadboard to see, if everything works like expected. While at the Breadboard, i also strongly recommend testing every LED, because I didn't tested mine, and of course i ended up with one not workig on my tree.

Also i said, i'm gonna tell you about those appropriate resistors, well here's a simple equation, where you can calcute the value of the resistor: R=(Ui - Uled)/Iled. Now you just plug in the values: Ui = Your input voltage; Uled = 3; Iled = 0,02; R = the value of resistor. So completed it looks like this: R=(Ui - 3)/0,02 and all you gotta do is put in your input voltage, type it into the calculator and voilá! you have your value.

The breadboarding is pretty simple, just follow the schematic i included, do everything properly and don't forget to double check everything. If you want to tweak the period of switching between the LEDs, play around with R1, R2 or C1. As i said in the beginning: "There's no need to be afraid of experimenting!"

So once you got it tweaked to fit your needs and you are happy with it, note your components values, so you don't later blame yourself for using the "default" values. Now we can move to the next step...

Step 4: LED Layout & Glueing

So now position the LEDs how you like it, once you're happy with your layout, mark the positions of them. Then bend the leads of every LED and also note the longer and shorter lead - you might want to be cautius when bending the legs of it for your later convinience of wiring.

Once all the leads are bent, start glueing them on the Xmas tree to your marked positions. Again, glue them efficiently for easy wiring.

If you have all the LEDs in place, we can continue to the next step.

Step 5: Soldering

So you have all your LEDs glued in place and you have your components ready. Alright! Let's solder!

So firstly we'll start with LEDs. Go over every LED you have glued on your tree and solder the resistor, which suits your input voltage (in my case 47Ohm), on to every LED. It doesn't matter on which leg you solder the resistor, but it's a good idea to choose for example the shorter lead, and then solder all the resistors to those shorter leads on other LEDs to keep track of the polarity of the LED.

Now that you have done that, you'll now need to group the LEDs into two groupes. These groups will then alternate turning on and off (eg. if group 1 is on, the group 2 is off and then the group 1 will switch off and the group 2 will switch on, if you'll use my "default" component values, the time for alternation will be average 50:50). Now solder wires and resistors just like shown on the first picture. Wire group 1 and group 2 separately though.

Once finished with the LEDs, you can now test them using two AA batteries. Also test group 1 and group 2 separately, so you now what to expect later.

Then when you're done with testing, we can start soldering the blinky circuit on to the perf board. It's a good idea to firstly lay the components on there without soldering, take a picture and then get them all out and start soldering from the lowest height components to the highest ones. Also lay the components somewhat logically, for example if you have to connect the base of a transistor to a resistor, put those leads next to each other. After you're done soldering the components, solder necessary jumper wires and wires of the LEDs and battery / wall adaptor and cut off any leads that are too long.

Now test it! This is the final test, so if it doesn't pass the test, than you have to go back and check for wiring errors and shorts. If you are absolutely positive about you've done everything corectly, it might be decoupling issues. Try putting a 10uF capacitor between VCC and GND. If that doesn't help, then PM me on Instagram @EEPblog.

If everything works, glue the PCB on the back of the Xmas tree and continue to the last step.

Step 6: Finish & Enjoy!

To finish it we'll glue the wires down or strap them together using zip ties to make it neat and nice looking. Now you just gotta find a place where to put it and it'll reliably blink untill you ran out of batteries or the wall adapter breaks down...


Also be sure to check me out on Instagram (@EEPblog) and YouTube (TwoSmartGuysLab)! Thank you for the support!

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