LED digital watch kit
If you can not afford a real NIXIE tube watch, there is an alternative. It is this 4-digit 7-segment LED watch kit. It costs less than 10 euros and you can find it on most Chnese resellers websites. It comes as a kit and you will need to do a bit of soldering and assembling.
After 2 weeks of waiting, the order arrived. All the parts were neatly packaged in a small ziplock bag.
The package was complete, including a schematic and even a button cell battery.
Arranging all the parts on the PCB was easy.
The list of parts includes:
- STC 15L204EA microcontroller
- DS1302 timekeeping chip
- 3x 10K resistors
- 2x 22pF ceramic capacitors
- 100nF ceramic capacitor
- 32768 Hz watch crystal
- 2418 4-digit 7-segment display
- 2x micro buttons
- Button cell battery cap
- Printed circuit board
This is the complete schematic of the circuit:
Time to solder all the parts on the PCB.
There are 4 holes on the left of the board to connect the programmer. The clock is programmed on the STC microcontroller and it is possible that this DIY watch project was used. That's good news that there is room to experiment and program new functions into your watch.
The last part of this project is to assemble the casing with the wristband. There are several layers, which need to be stacked in the right order.
Luckily the supplied manual is very clear on how to do this.
This is a close up of all the layers.
And another close up picture of the face of the watch.