Another one of a kind DIY clock soldering kit. The time is displayed as HH:MM:SS on easy to read 7 segment LED displays. The timekeeping circuit is an adaptation of our basic binary coded decimal TTL clock circuit that is embedded into most of our clocks. The circuit is based on the 74LS90 BCD counter IC. The binary coded decimal format is decoded using a 74LS48 BCD to 7 segment decoder IC. A 32.768Khz crystal oscillator is the time base. 3276800 is divided by 2 14 times to get a really accurate 1Hz square wave. It keeps time about as well as a digital wrist watch.

Along the top of the PCB is an 8 pin Dupont header for each digit. The value of each digit is output on these headers in binary. An optional 7 segment jumbo LED add-on display will be available soon. On the left side of the PCB is a 6 pin Dupont header for remotely setting the time.

This kit is straightforward to assemble. Only novice soldering skills are required. There are no surface mount parts. As long as every component is placed in the right spot and there are no cold solder joints, everything should work. The 32.768Khz quartz crystal oscillator's case must be glued to the PCB for accurate timekeeping. There is no separate page with assembly instructions, however this open source design can be found on our open source designs page. The crystal oscillator’s case needs to be glued to the PCB for accurate timekeeping.

All components and the PCB are included. You will need a USB-C power supply, solder and a soldering iron.

The open source design can be found here: https://www.boltind.com/6-digit-7-segment-ttl-led-clock/