IKCH-31 LED Clock Series
There are three LED clocks in the IKCH-31 series:
- IKCH-31C — the original clock feature 156 LEDs (60 second, 60 minute, and 36 hour hands)
- IKCH-31I — a much-improved 247 LED version (120 second, 60 minute, 48 hour, and 19 moon-phase hands)
- IKCH-31K — a much simplified moon-phase only clock
IKCH-31C
This is the original clock. It's built on a 26cm x 26cm PCB, and features mostly "surface mount" components. I put surface mount in quotes because there are standard through-hole DIPs on the back, except that they have the legs bent so that they can be surface mounted. As well, there are a few connectors and other intrusions that go through the board. I built 5 of these and distributed them to friends and family, and retained two. The hour hand LEDs were a bitch to solder because I had made their spacing way too tight — I ended up shaving the silicone protection off the LEDs just to get them all to fit.
The software is configurable to allow a 1/60th of a second "sweep" hand that goes counter-clockwise during AM, and clockwise during PM.
The hardware allows driving via TTL serial or GPS, and includes two pushbuttons on the back that I had intended for hour-offset so that you can do daylight savings time. Instead, though, I just hardcoded the software to Eastern Time.
IKCH-31I
This is the "corrected" version; the hour-hand LEDs were pushed much further from the center. It's built on a more expensive 32cm x 32cm PCB. Given the extra real estate, I was able to double up the outer second hands to 120, making for a much smoother sweep. What to do with the centre space inside the hour hand area? Well, I added 19 WS-2812 RGB LEDs, and the software implements a moon phase complication.
IKCH-31K
And speaking of moon phase complications, the 31I model is a reduced version that shows only the moon phase.