Watch antenna

Usually a small coil. You can see it in this tear-down video at 6:30min:

Thanks - I hadn't checked YT teardowns. Someone asked a comment about whether or not the antenna was ferrite cored, but unfortunately it wasn't answered. At 7.21 in the video there is a close-up and it looks like there is a ferrite core.

Tiny ferrite rod. See Fig 15

Nice of you to not provide the maker and model number of your watch. So, you get a general answer instead of specifics.

The encoding method changed in about 2012 from AM modulation to phase modulation:

I suggest you check the DoM (date of manufacture) of your unspecified model watch and see how it was made before or after 2012.

Good luck.

Oops. Bad choice of URL. This is better:

"WWVB Time Signal Broadcast: A New Enhanced Broadcast Format and Multi-Mode Receiver"

I opened up my Casio radio watch to replace the battery when it was emopty I do think I noticed a what looks like a small ferrite rod?

But lemme use AI, so typed in Chromium browser: what sort of antenna does CASIO use in its radio-watches?

That gives this:

Key Features of the Antenna High-Sensitivity Reception: The antenna is designed to capture standard time radio waves with high sensitivity, ensuring accurate timekeeping. Durability: Its shock-resistant construction allows the antenna to withstand rough conditions, making it suitable for outdoor and rugged use. Global Compatibility: The antenna enables the watch to receive signals from multiple time transmission stations worldwide, enhancing its functionality and accuracy. Reception Capabilities Casio's antenna technology allows watches to synchronize with time signals from various regions, including:

Region Frequency Transmission Station Japan 40kHz / 60kHz JJY (Fukushima, Kyushu) North America 60kHz WWVB (Fort Collins) UK 60kHz MSF (Anthorn) Germany 77.5kHz DCF77 (Mainflingen) China 68kHz BPC (Shangqiu) This advanced antenna technology is a key component of Casio's commitment to providing precise and reliable timekeeping in their radio-controlled watches.

 Wikipedia  gshock.casio.com Explore More  What are the benefits of using a shock-resistant antenna in Casio watches?  How does the amorphous material in Casio antennas enhance radio signal reception?  What alternative antenna technologies exist for radio-controlled watches?

Google knows everything!

I have 2 Casio radio watches, both work great An older model an a new one a year or so old

Could it be some sort of rubber-based ferrite (like the magnetic rubber strips around fridge doors)? Ordinary ferrite might shatter if you dropped the watch but rubber ferrite woudn't - it could also be moulded into a shape that would better fit the watch case or perhaps have better signal-gathering properties.

I guess that's the nearest we'll get to something actually stating the watch (rather than clock) antenna is ferrite, but see my reply to Liz Tuddenham.

You might be sorry you asked about the make and model as it's a long tale of woe! But since you asked...

The watch is a Junghans Mega Solar Sinus Ceramic, bought new in 2010, but according to Junghans it was then already seven years old! It went wrong several times, and I had to have the "movement" replaced after three years (Junghans expected a 10-year life, which tied in well with the dates). The purchase turned into a /very/ expensive mistake. (see model 053/1212.44 at

Basically, the watch would now and again show an incorrect time and sometimes date. It could be wrong by a few hours and an odd number of minutes. I assumed a faulty component decoding the time signal from DCF77 Mainflingen (about 750km away, so well within range), but wondered if it was occasional interference overriding the time signal. An internet search revealed a number of reports of similar incorrect time showing with Mega Solar watches.

Although this NG is s.e.d, there is only very rare mention of the "external human interface" part of design. I mention this because the Junghans watches have a very unusual design, in which interactive function is stripped down to the utmost simplicity, and therefore fails if anything unintended happens. The watches have no crowns or fine adjustment of any sort. All they have is a tiny button on the back, which can be operated by a ballpoint pen or something similar, and it only responds in one of three ways. Press for more than 9 seconds, and the hands rotate to 1200 exactly, where the watch then awaits the next signal from DCF77. Once it has received that the hands rotate to the correct CET setting. If the button is pressed for less than 3 seconds, the hour hand moves forward exactly one hour (as I'm in the UK we're on CET -1, and it's a pain to set the hour as I have to press the button 23 times!). Press between 3 and 9 seconds and it resets to CET time. That's it. So, as long as it picks up the time signal correctly, it shows the time and date accurately.

But what happens when it no longer responds to the time signal? Well, Junghans thought of that as a temporary issue by having an internal crystal to control the time if the transmitter was no longer in range. That internal crystal is pretty accurate - about 2 seconds a month. But over the almost five years the watch hasn't responded to a signal, it's now about 2.25 minutes fast. It also displays day and date, and here we come to an interesting oversight. As I mentioned, Junghans had foreseen the lack of a time signal when out of range, and as well as the clock they'd also included a calendar. So the watch "knew" that when it came to the end of the month, the next date it displayed would be "1" (it gets the 30 or 31 days for the month correct). However, the calendar wasn't meant to go past a year, so it didn't include 29 February! Today the day/date display is showing SAT 29. :-)

Well before 2012, but it doesn't use WWVB.

I know that it's radio control is unrepairable.

This shows a Junghans watch with a completely different antenna - not ferrite. See

I don't speak German, and can't get the caption autotranslate to work. Perhaps Jan can help.

The AI returns mostly irrelevant babble. Who cares about mechanical strength and corrosion resistance in a watch antenna core? The relevant properties would be permeability and loss at the operating frequency, thermal properties, core geometry, maybe some optimal coil parameters, and how to mitigate the screening effect of nearby metal parts.

I've been playing with some cheap Chinese DCF77 receivers lately. Cute! Works quite well, but I have to keep them away from my laptop.

Jeroen Belleman

Preventing breakage is a mounting problem. A little bit of resilience does wonders. Amorphous metal cores are stacks of very thin bits of quite flexible tape. Razor sharp, but not terribly breakable. The stuff is made by shooting a jet of molten metal at a rapidly rotating copper wheel.

Jeroen Belleman

I do, there was some water / moisture in it one day.

As a kid I build MW AM crystal radios with a ferrite rod as antenna At these low frequencies like DCF77 it is the only option, a ferrite rod with lots of turns. I have a Xiron DCF77 desk / alarm clock too, perfect time keeping, runs years on a simple Eneloop AA battery without recharge:

For more local precision I have a Rubidium 10 MHz reference.

I have GPS problems now my neighbor installed solar panels Scope probe free in air shows switching frequency spikes. Even magnetic compass goes haywire ...

Anyways I do have an old mechanical alarm clock somewhere too. And the church tower about a mile away lets you know every 30 minutes that time flies...

Do you have a doomsday clock there at CERN? beep beep beep

When I find myself in times of trouble my computah beeps to me Beeping sounds of wisdom let it beep let it beep Let it beep let it beep let it beep let it beep Beeping sounds of wisdom let it beep beep beep

Google says: The time can be set using the Junghans MEGA app. The dial of each watch is protected by sapphire refers to:

Bit expensive it is!

Mine is not solar powered but will run for about 2 years on a cheap battery, easy to replace (with the right scewdriver)

Everybody has a cell phone now, so why have a watch?

Are the WWV rf and vlf stations still transmitting?

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

I often forget my phone, but never my watch.

Indeed. See

The amorphus magnetic materia mentioned earlierl is a metallic ribbon, and is not brittle.

Joe

Not every body has a cellphone, some are even out of range of cellphone towers. And cellphones get their time from the network,

The watch (here) from DCF77 that has a very wide range

When doing navigation at sea without GPS and a sextant precise time comes in handy too. Especially with all the GPS jamming going on. I have a simple one:

Yes, WWV is still transmitting and continues to broadcast time and frequency information 24/7. It is operated by the U.S. National Institute of Standards and Technology (NIST) and has been in operation since 1919.

I can select world areas on my watch.

- The watch is more convenient and doesn't require searching for where I put the phone.

- I can't read the smartphone display in bright sunlight.

- The wrist watch is generally cheaper (except for collectors watches).

- Fashion statement.

- Apple watch acts as a display and ringer for the iPhone.

- Apple watch can be uses as a heart rate and blood pressure monitor.

Yes. WWVB (60KHz) was operating at reduced power from Apr 7, 2024 through Oct 11, 2024 due to the very large transmit antenna falling apart. The drop in signal level was noticeable, but not catastrophic. My various receivers continued to reliably synchronize to WWVB at the time of night when signals were strongest. My various cheap watches and clocks required carefully positioning the watch for maximum signal strength.

Having WWVB operate at reduced signal strength for 6 months inspired a number of rumors that WWVB was off the air. A few months earlier there were rumors that federal funding would be lost because the low and medium frequency time clock services had become obsolete because satellite based services (GPS) had replaced them. For example, a GPS based bicycle computer which could be used as an oversized wristwatch.

There aren't any public pay phones any more, so without a cell phone you are out of touch.

OK, you save money by not having a phone.

Oh.

I talk on my phone maybe a minute per day, mostly to coordinate with Mo. I use it a lot more as a camera and an RPN calculator, and occasionally as a clock and stopwatch.

It does run the Google Home app for the cam and thermostat at the cabin.

The maps are handy, once in a while. Remember when you had to buy a map at a gas station?

I never text. That seems to be a sick addiction.

Yesterday a plumber climbed up into our crawl space at work and aimed his phone at the label on the water heater. The phone read the maker and serial number and told him that it was made 27 years ago. I expect it might leak soon.

John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics

Jan Panteltje schreef: |--------------------------| |"Google knows everything!"| |--------------------------|

False! LinkedIn owns a lame search engine, so LinkedIn failed on March

Google also failed on the same day to find it (whether from LinkedIn or from any backup). At least Google has the excuse that Google (still) has not downloaded this backup, but it is not a good excuse as Google did download that backup:

/home/gloucester/http_logs $ grep Googlebot * | grep LinkedIn_comments_29-01-2026_downto_circa_29-10-2025 grep: coimheas: Is a directory gloucester.insomnia247.nl_access.log:66.249.69.236 - - [06/Mar/2026:14:59:10 +0100] "GET /Scholastica_or_LinkedIn_connivance/LinkedIn_comments_by_myself/LinkedIn_comments_29-01-2026_downto_circa_29-10-2025__Edge_took_12_minutes_to_make_this_249-page_PDF_file.pdf HTTP/1.1" 200 248918217 "-" "Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.7559.132 Mobile Safari/537.36 (compatible; Googlebot/2.1; +