Thinking to build an all-tube clock. There are a few inspirations by others.
The most compelling is the Scientific American inspired design based on a 120kHz quartz crystal, but this provides 60Hz for driving a synchronous motor analog clock. This design is based on AMV (asynchronous multivibrator) dividers similar to legacy TV synch oscillators. According to the updated design, divide-by-10 is the best one can reasonably get from an AMV stage, but it only takes one tube for each divider.
For a digital display, one can take inspiration from the HP AC-4J/K/L with 4-bit counter, decoder and nixie! One could even just buy 6 of these and modify them a bit to count from 00:00:00 to 23:59:59.
Here is a hybrid idea:
- Start with AC line and divide to 1Hz using two AMV stages (two 6SL7)
- Design 3-bit (0-5) and 4-bit (0-9) stages inspired by the HP counter.
sec: (3) 5963 tubes 10 s: (4) 5963 min: (3) 5963 10 m: (4) 5963 hr: (4) 5963 10 h: (2) 5963 Total: 20 5963 tubes
HP use neons to decode binary to decimal and "photoconductor plate" devices to drive the nixies!
