This open source design is available as a soldering kit HERE. Everything is included!
This is an easy to read 7 segment LED clock that displays the time as HH:MM:SS. The basic timekeeping portion of the clock is our standard TTL logic clock circuit based on the XD74LS90 binary coded decimal decade counter, and a 32.768Khz crystal oscillator. The BCD output format is decoded to a human readable 7 segment display format with 6 74LS48 BCD to 7 segment decoder chips. Along the top of the PCB is 6 DuPont headers that output the value of each digit as a BCD value. More add on displays for this header will be available soon. On the left side of the PCB is a 6 pin DuPont header that can be connected to buttons to set the time remotely.
You may question the lack of resistors for the 7 segment LED’s. They are built into the 74LS48 chips.
Open Source Design Files
The open source design files are below. There is an easy to read schematic in PNG format. The other JSON files can be imported into Easy EDA. I do not like Gerbers because they can not be modified. You can import the JSON into Easy EDA and export your own Gerber.
