Back in 1978, the world was a bit different. There was no Raspberry Pi, no Internet, and not even an ESP32 to build projects with. And rather than order electronics kits from Tindie or Adafruit, [Dr. Francitosh] selected this binary clock with his mother from a catalog, and made the order via mail. Simpler times. The good Doctor, AKA [Greg Smith], was a young electronics tinkerer, and his mother wanted a good project-in-a-box to show off his skills. Thus, a Greymark Binary Clock was ordered and assembled. Then, sadly, the beloved clock crashed from its proud mantle position, doomed to never to blink or blip again. Or was it?
[Greg] finally got his hands on the old project, and just had to get it working again. The inner circuit board was broken right through, and that presented an opportunity to not just repair the clock, but to teach the old dog some new tricks. Before we get there, there’s a fascinating teardown of how the original circuit used a pair of 7490s to take the 50 or 60 Hz of grid power and downconvert it to a stable 1 hz pulse. From there, a series of even more 7490 Binary Coded Decimal counter chips keep track of the ticking seconds, minutes, and hours.
While this clock may be from a simpler time, [Greg] doesn’t live in that time any longer. He saved the project box, panel, original LEDs, and switches. But the new heart of this reborn machine is a Raspberry Pi Pico W. This gives full emulation of the old behavior, as well as setting the time over Bluetooth, grabbing time from NTP, and even listening for ..
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