These Christmas tree kits are very popular this Holiday Season. You can get a 3D LED Christmas Tree Kit of your own from Amazon at http://amzn.to/1IH2rkv
In December, we featured these 3D Tree kits in HackerBoxes (THE Subscription Box for DIY Electronics) but we weren't very happy with the details of operation and build instructions that were available online, so we ventured to put something a little more useful together to share. We hope you find it useful and have a look at HackerBoxes.com
10K ohm resistors
R1, R3, R5 on both "Tree PCBs"
1K ohm resistors
R2, R4, R6 on both "Tree PCBs"
2K ohm resistor
R7 (only on one of the "Tree PCBs")
C1, C2, C3 on both "Tree PCBs"
Q1, Q2, Q3 on both "Tree PCBs"
Each of the 10K resistors and 47uF capacitors form an RC oscillator
that periodically pushes the associated transistor on. The three sets of RC
oscillators are transistors are connected in a loop to keep them cycling out of phase
which makes the blinking appear random around the tree. When the
transistor is "on" current passes through a bank of 6 LEDs and their 1K
current limiting resistor causing that bank to blink on. If you're looking for an adveture, trying adjusting the value of one (or more) of the 10K resistors a bit to change the blink rate of the LEDs.
Populating the Resistors
Begin soldering by stuffing the resistors. Resistors are not
polarized in anyway, which means that you can insert them in either
Use a resistor color code chart or app to identify the
different resistor values and make sure to insert them into the correct
In some of 3D Christmas Tree kits, a couple of the 1K
resistors are replaced with 330 ohm resistors. When available, the 330
ohm resistors should be used for R2 instead of the specified 1K
resistor. According to the numbering system that we have used, R2 is
the current limiting resistor for the green LED bank (D1-D6). Using
this lower resistance allows the green LEDs to glow a tiny bit brighter,
which can mitigate the fact that green LEDs often appear a little
dimmer than the red and yellow LEDs.
In the end, the value of the
current limiting resistors (R2, R4, R6, and R7) is somewhat forgiving
and can anywhere around 300 ohms to 3K.
The value for R7 is
specified on the higher end (at 2K) because R7 is the current limiting
resistor for the red LED D19 at the top of the tree. Since D19 does not
blink, it may appear much brighter, so the higher 2K resistance
balances the brightness a bit with respect to the other LEDs.
Are you new to soldering? There are a lot of great guides and videos online about soldering. Here is an example:
If you feel that you need additional assistance with soldering, try to find a local
maker group or hacker space in your area. Also, amateur radio clubs
are always excellent sources of electronics experience.
When soldering in the transistors, be sure to align the flat side of the
transistor to the flat side of the white outline on the printed circuit
board (PCB). This ensures that the transistor is wired in the correct