LED Clock DIY Kit with Melody Alarm (option)

This big (21 x 7.5cm display) LED Clock DIY Kit runs on an Arduino Nano, and you can either use the firmware* we provide for download, or program your own application. You could even combine it with our WWVB or DSF77 Atomic Clock receivers, if you feel skilled enough.

Arduino Nano compatible module, power supply cable and melody chips sold separately (see end of description).

The Arduino demo sketch includes operating instructions within the code header. The Arduino sketch can be downloaded here: V3 demo code

The following functions are included in the demo code:

• 12 or 24 hour time
• date
• time only or date and date intermittent
• seconds on or off
• brief display of date by pressing the snooze button
• automatic display dimming (adjustable behavior by changing parameters in code)
• 3 independent alarms (off, weekdays, weekend, every day)
• alarm snooze (duration adjustable)

The firmware version requires the following Arduino libraries:

1. EEPROM.h
2. TimerOne.h
3. Wire.h
4. RTClib.h
5. TimeLib.h
6. DS1307RTC.h

If not already done, install the libraries using the library manager in your Arduino IDE.

The LEDs are dual-color types, producing green light in one polarity and red light in the other one. Depending on your taste, you can have the entire display red or green, or the seconds in a different color, or the colon and alarm LED, or what ever combination you think is cool. If you push a 3V lithium button cell between the leads of one of these LEDs, you can see how the colors will look like without blowing the LED up. Just don't do it for longer then a second.

The alarm function is only available when a melody chip is installed. The kit includes a socket for it to make switching the melody chip easy. You will find the 4 different melodies in our shop: Love Me Tender - Für Elise - Happy Birthday - Jingle Bells

The clock is easy to assemble; all parts are through-hole and their positions are clearly printed on the PCB. Just match the part positions and the values from the schematic. After you finished the 2 separate circuit boards (the main board and the display board), you attach them using nice big solder blobs on both sides (top and bottom) of the main board. The image gallery shows you how to do this.

Assemble the photo resistor as the last part, after both PCBs are already connected, and align it with the hole in the front panel.

Now you load the code to your Arduino Nano module, and you are ready to go. The code should be uploaded when the Nano is on the board and the RTC backup battery is installed. This way, the RTC will set to the time and date of your computer.

Download PDF manual and assembling instructions here.

The kit includes 2 PCBs and through-hole parts. The following parts are sold separately:

1. Arduino Nano V3: Available with Mini-USB or USB-C interface.
2. Melody chip: We have 4 different melody chips to chose from. No chip means no alarm!
3. Power supply cable: For better brightness, we recommend to power the clock through a 5V USB power supply cable.

* The provided code is without any warranty. It provides basic functions as described but might have some bugs. Your contribution can help make it better.

UNIVERSAL-SOLDER has the best selection of LED Clock Kits:
4-Digit DIY Clock with alarm, countdown and more
6-Digit DIY Clock kit
6-Digit DIY Clock for Arduino Nano
4-Digit LED Wifi-Clock Module