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PROJECTS ArduinoGravitySolar

How to Make a Holiday Window Decoration with LED Strip

DFRobot Nov 28 2019 910

Things used in this project

Hardware components

DFRobot Solar Power Manager (for 9V/12V/18V solar panel) ×1

DFRobot Gravity: Analog Ambient Light Sensor For Arduino ×1

DFRobot Gravity: I2C 3.7V Li Battery Fuel Gauge ×1

DFRobot DFRduino UNO R3 ×1

Silicon Solar Panels(9V) ×15

Lithium Battery 3.7v/10000mah ×1

DFRobot Gravity: I2C DS1307 RTC Module ×1

WS2812B RGB led (combines with enameled wires and 3M twin adhesive) ×80

NPN triode (10k resistor) ×1

Software apps and online services
Arduino IDE

Hand tools and fabrication machines


My friend said that it is wasteful to make a holiday window decoration with an LED strip. All in all, the holiday only lasts a couple of days, so we have to split and remove it just after a few days. On second thought, that’s the truth.

This time, I want to make something useful. The smartphone should be powered off during charging. You know smartphones are a little dangerous when be powered. (SAMSUNG S10 explosion…) But how could we check time whenever we want? Of course, a clock.

Surfing the internet but failed, big clocks take too much space, small ones are hard to check the time. Well, a bright idea came up with a brainwave, I decide to make my own clock.

It is a rocky road but finally, I succeed. When heard of praises like it is beautiful, all these are worthy.

Once open the door, a cute window clock jumps into my sight. With thousands of lamps in dark, the clock is so charming. At this time, joys spilled out from my heart, I truly know the answer to what’s the reality from the movie Forever Young.

Clock on the window---Light Year

Design Idea

Combine solar power manager with 15 solar panels to make an independent electricity supply to power the clock. The solar power helps us get rid of the restrict of external wires and the window would not be choked by long wires and switches. According to the energy amount, the clock responds to 3 modes.

Mode1(energy>70%): the clock keeps light ON.

Mode2(70%>energy>50%): the clock flashes to save power.

Mode3(energy>50%): the clock keeps light OFF but wakes up periodically. With the decrease of energy, its sleep time will increase exponentially.

In this way, the clock can work for one month even without any sunlight to supply energy. And the light sensor can adjust the clock lightness to adapt the environment light changes. So, no matter what whether it is, sunny, cloudy or night, we all can enjoy a comfortable watching.

Visual DesignConsidering people always pay attention to 2 values hour and minute, I weaken the visual proportion that the second takes, and simplify the second to matrix flash.

Talking about the Solar Power Manager, we should know its multiple ports.

There are 8 ports at least:

Micro USB input x13.7V inputs x2 (the 3.7v lithium battery can be charged when solar panel inputs or micro USB inputs are provided)7v~30v solar power input x15V 1.5A output x13.3v 1A output x19v/12v 0.5A output x15v 1.5A USB output (which can directly supply UNO) x1

The maximum charge current up to 2A. The MPPT (Maximum Power Point Tracking) algorithm is adopted which maximize the solar power and capture the solar energy effectively. Just like a talented conductor who holds a delicate baton, it performs excellently in every wave. Therefore, all electrons move to destinations in order.

Connection Diagram

Let’s make it!


Laser cutting drawing (the purple lines are indications for soldering)

Laser cutting 3mm boards (the super small dots next to square holes are to indicate the direction of the LED notch).

Allocate LEDs

Soldering enameled wire

During soldering, my friend just said: “Oh my gosh, are you wanting to solder to die?” Well, finally I survived.

Adhere the board to the window, it seems a little tilt. Try my best to hold me back from tearing it apart (I am Virgo… and a little obsessive). Power ON, many LEDs just burnt immediately without any reason. So I have to take all of them down and solder again.

Try the second, perfect straight post! Now it fully relief me.

Put 3M twin adhesive(1mm) to the back of LEDs:

Connect solar panels in parallel, then paste them in the direction of window frame with 3M twin adhesive, put hot glue to the loosen parts.

Fix solar power manager, Arduino UNO, and sensors near to LEDs.

Arduino UNO and Lithium battery:

Tear all 3M adhesive in the LED board apart, take tools to paste to the window in parallel and split LED and board apart slowly and carefully.

LEDs are allocated in the inner side and the controllers and others are allocated on the other side of the window. So we need to probe a small hole to go through the window frame and make LED enameled wire to the outside.

Wiring as the connection diagram suggests and burn the program.

Put the clock between 2 glasses.

The glass reflections and refractions make a fantastic infinite space effect. It looks more layering.

Define the color

Well done!


Connection Diagram