71–80 of 180 posts
I made a LED matrix clock using esp32 syncing time with ntp server every hour and an external RTC to do time keeping if my network is down, and it runs perfectly for years, with accuracy +-1s to time.is. Never have to do setting except the first boot to setup wifi.
I was tempted to go the Atomic Clock route, based on actual cesium oscillators, having found a cheapish ($999) used CSAC on ebay[1]. However, once I started digging into the data sheets[2], I found something unacceptable, Pin 1, labeled "Tune", an analog tuning input.
It was then that I learned that while the Cesium vapor cells were accurate, they aged, and drifted, unlike a properly degaussed and Zeeman harmonic calibrated Cesium Beam atomic clock, which is a primary standard.
Further demotivating was learning they have a 5-10 year service life. That's a lot of money to pay for what's essentially a better OXCO.
I'll stick with GPS disciplined oscillators for now.
[1] https://www.ebay.com/itm/327134074179
[2] https://www.mouser.com/datasheet/2/523/Microsemi_CSAC_Space_...
Wouldn’t it make more sense to build a GPS clock?
I can't decide how I feel about this article. On one hand, it's great. It's great that the author wanted to get something done, and thanks to the marvels of modern tech, they could do it with very little effort. But on the other hand... gosh , this was about the simplest software engineering challenge imaginable (toggle some I/O pins) and the simplest design task imaginable (make a featureless rectangular box). And t…
Earlier quoted context omitted.
I was going to mention an Atomic Clock. I use one in an RV and it sets itself even outside of cell phone range. I know it uses a radio signal of some type but I have no idea how it works. It rights itself within a few minutes of time changes, battery loss, or the like.
It's fascinating reading if you're interested in finding out the details: https://en.wikipedia.org/wiki/WWV_(radio_station)
This clock still sits on my nightstand. The backlight stopped working years ago, the cheap plastic case is cracked, the numbers on the dial from 12 to 5 have crumbled away. But it keeps perfect time! It is also silent (no ticking at all, no quartz crystal) and has no battery to charge or worry about leaking
I'd pay quite a bit for a replacement, but such clocks haven't been made in over 30 years. An "atomic" clock is cool, but the signal doesn't reach where I live.
In 1982 I purchased a GE analog alarm clock which plugs into an electric socket, has a gentle backlight and a snooze button. It cost 4-5 dollars. This clock still sits on my nightstand. The backlight stopped working years ago, the cheap plastic case is cracked, the numbers on the dial from 12 to 5 have crumbled away. But it keeps perfect time! It is also silent (no ticking at all, no quartz crystal) and has no batter…
https://timestation.pages.dev/
I use it when the daylight saving time switch occurs as not all of my clocks will get the time every night. But this isn't so useful if you never can receive the signal.
That way all the microwaves of the world could listen in and update their clocks accordingly