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Casio-F-91W die-shot

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Re: Casio-F-91W die-shot

#51

Post by frosted-flakes »

TedDoesntTalk wrote: post #27
mmaunder wrote: post #24

I'm a big fan of the F105W which is basically the same watch with a vastly improved backlight that lights up the whole LCD. It makes a great watch extremely usable at night. I'd also recommend the Casio G-Shock GWM5610 which admittedly is about 5 times more expensive at $111 but it has UTC time and is absolutely bulletproof, along with radio sync and solar with solar charge indicator. It's currently my favorite among…

> F105W which is basically the same watch with a vastly improved backlight Can’t stress this enough. The F-91W is useless at night because the backlight brightness is terrible. The F105W has an indiglo-style “EL” light that is very effective. The two watches are nearly identical from an aesthetic perspective. The functions are identical as are the buttons.

How does the brighter backlight affect battery life? Doesn't the original model have a 7-year battery life?

Re: Casio-F-91W die-shot

#52

Post by dougSF70 »

jimmyjazz14 wrote: post #48
mmaunder wrote: post #24

I'm a big fan of the F105W which is basically the same watch with a vastly improved backlight that lights up the whole LCD. It makes a great watch extremely usable at night. I'd also recommend the Casio G-Shock GWM5610 which admittedly is about 5 times more expensive at $111 but it has UTC time and is absolutely bulletproof, along with radio sync and solar with solar charge indicator. It's currently my favorite among…

I don't really understand your comment about avoiding Seiko (and yes as a Seiko collector I'm a bit triggered). In my experience Seiko makes absolutely great quality watches still with maybe the only issues generally being the occasional misaligned chapter ring though I pretty much only collect Seiko mechanical watches so maybe the situation is different with their quartz watches. Citizen also makes some particularly…

Seiko 5 automatic movement is on a par with the Rolex automatic movement according to my friend who is an official Rolex repairer.

Re: Casio-F-91W die-shot

#54

Post by jimmyjazz14 »

dougSF70 wrote: post #52
jimmyjazz14 wrote: post #48

Earlier quoted context omitted.

I don't really understand your comment about avoiding Seiko (and yes as a Seiko collector I'm a bit triggered). In my experience Seiko makes absolutely great quality watches still with maybe the only issues generally being the occasional misaligned chapter ring though I pretty much only collect Seiko mechanical watches so maybe the situation is different with their quartz watches. Citizen also makes some particularly…

Seiko 5 automatic movement is on a par with the Rolex automatic movement according to my friend who is an official Rolex repairer.

They are often quite similar in design though I'm guessing the Rolex uses quite a bit higher quality materials.

Re: Casio-F-91W die-shot

#55

Post by koonsolo »

mmaunder wrote: post #24

I'm a big fan of the F105W which is basically the same watch with a vastly improved backlight that lights up the whole LCD. It makes a great watch extremely usable at night. I'd also recommend the Casio G-Shock GWM5610 which admittedly is about 5 times more expensive at $111 but it has UTC time and is absolutely bulletproof, along with radio sync and solar with solar charge indicator. It's currently my favorite among…

I have a casio g-shock MTG with solar and radio sync that I bought more than 10 years ago. Wear it almost every day. Battery indicator is still at full. Once I had to buy a small metal rod (for a few euros) for the metal strap, and still going strong.

Re: Casio-F-91W die-shot

#56

Post by [deleted] »

mmaunder wrote: post #24

I'm a big fan of the F105W which is basically the same watch with a vastly improved backlight that lights up the whole LCD. It makes a great watch extremely usable at night. I'd also recommend the Casio G-Shock GWM5610 which admittedly is about 5 times more expensive at $111 but it has UTC time and is absolutely bulletproof, along with radio sync and solar with solar charge indicator. It's currently my favorite among…

[deleted]

Re: Casio-F-91W die-shot

#57

Post by dekhn »

Tor3 wrote: post #25
vasqw wrote: post #12

I bought one of those recently and I was surprised by how inaccurate it was. It drifted like 15 seconds every month. From what I've been reading, that is normal, but I was surprised - with all the technological advances that we have it is odd to think that cheap timekeeping is not a solved problem yet! Also: how is the software of these watches without a CPU designed? Is it something like Verilog or whatever?

At around 1976-1977 I bought one of those fancy new LED wristwatches, where you pressed a button and the time lit up in red. Straight out of James Bond, as I recall. As I was studying electronics at the time I brought the watch to the lab and opened it and connected a frequency counter to the oscillator, you could clearly see the crystal and a little trimming pot (I don't remember by now if that was a pot or somethin…

People who are curious about this, it's worth reading about quartz oscillators in watches and in particular, methods of calibrating them: https://en.wikipedia.org/wiki/Quartz_clock#Inhibition_compen...

Re: Casio-F-91W die-shot

#58

Post by myself248 »

vasqw wrote: post #33
sn_master wrote: post #22

Earlier quoted context omitted.

> all the technological advances that we have This is 34 years old technology. You can get GPS watches relatively cheap and they'd sync with satellites automatically and always remain accurate.

Yes. I ended up buying a GWM5610 which synchronises through radio. It's cool. But still I would have hoped there would be a better "local" (i.e. self-reliant) solution.

There's software for the Beaglebone PRU so you can generate your own WWV signal, for receivers buried too deep into buildings or otherwise suffering from poor signal.

Of course, with any HackRF you can also generate GPS signals.

But it would be a lot less necessary if the watches had reasonable temperature compensation. Obviously the crystal frequency shifts with temperature, and they're typically adjusted to achieve best accuracy when at "wrist temperature" for 16 hours a day, and "nightstand temperature" for 8. Any deviation from that, routine, and crystal accuracy gets terrible.

Temperature-compensated crystal oscillators (TCXOs) switch tiny capacitors in and out of (or bias a varicap in) the crystal loading circuit to "rockbend" its response and keep it nearly flat across a wider range of temperature, but this requires extra power. A minuscule amount, but it adds up quickly when your budget is nanowatts.

However, there's another way to do it, which I'm astonished not to see: You don't need to alter the crystal's actual frequency if you can just adjust the number of counts that represent a second. Every once in a while (every few minutes would be plenty), take a temperature reading, look it up in your calibration table, and stuff or steal a few cycles from the counter register.

This takes basically no additional power, adds one more calibration step at the factory, and should bring drift down by an order of magnitude, into TCXO territory. Seconds per year, not seconds per month. That would be something to crow about, and it baffles me that Casio and others never went that route.

Re: Casio-F-91W die-shot

#59

Post by smackeyacky »

Tor3 wrote: post #25
vasqw wrote: post #12

I bought one of those recently and I was surprised by how inaccurate it was. It drifted like 15 seconds every month. From what I've been reading, that is normal, but I was surprised - with all the technological advances that we have it is odd to think that cheap timekeeping is not a solved problem yet! Also: how is the software of these watches without a CPU designed? Is it something like Verilog or whatever?

At around 1976-1977 I bought one of those fancy new LED wristwatches, where you pressed a button and the time lit up in red. Straight out of James Bond, as I recall. As I was studying electronics at the time I brought the watch to the lab and opened it and connected a frequency counter to the oscillator, you could clearly see the crystal and a little trimming pot (I don't remember by now if that was a pot or somethin…

Get a Casio G-Shock. The 800 models can sync with your phone and the time is auto corrected. I bought a GBA-800 from a pawn broker - out of the dozen or so watches in my box it's the one I reach for if I have to know what time it is accurately.

Re: Casio-F-91W die-shot

#60

Post by dekhn »

kens wrote: post #39
aliljet wrote: post #28

This is a remarkably interesting image. How do these guys even get these shots? I'd love to do this on all kinds of things at home..

For die photos, you want a metallurgical microscope, one that shines light down through the lens. A typical microscope shines the light from underneath, which works well for biological samples, but not so well for chips. The tricky part is decapping the chip. The easy way is to get a ceramic package, which you can decap with a chisel. Or a metal can, which you can open with a hacksaw. With a standard epoxy package, y…

Have you tried ImageJ, specifically the Grid/Collection Stitching? I use it for microscope stitching and it works pretty well.
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