Just How Water Resistant Is The Casio F91W?

June 18, 2021 by Lewin Day 25 Comments

Water resistance is an important feature of a modern watch. It makes wearing the watch far more practical in this modern world of sudden rainstorms and urban water balloon ambushes. The Casio F91W, one of the company’s most popular watches, is claimed to be water resistant to “30 meters”, which in ISO parlance, means it is suitable for splashes and rain resistance only. [Rostislav Persion] wanted to get a better idea of what this really meant, so set about investigating for himself.

The first step was to simply immerse the watch under 5.5″ of cold tap water while pressing the buttons and observing for any signs of water ingress. Already, the watch proved it is far more than just rain resistant, so [Rotislav] decided to disassemble the watch and learn how it achieved this.

Disassembly revealed that the watch’s case was entirely sealed, except for three buttons. The buttons, however, are specially designed in order to seal with the plastic case of the watch. Each button consists of a stainless steel pin, machined to be larger on the outside-facing side than the inside. The buttons also have a rubber O-ring seal to allow them to move in the case without allowing water to leak inside. [Rotislav] then compares the simple design to buttons used on watches with higher water resistance ratings, which boast multiple O-ring seals and more complex designs.

Given [Rotislav’s] results, we’d be far more confident getting our affordable Casio watches a little wet. Obviously, we wouldn’t expect to make a warranty claim if damage occurred from use outside the specs, but it’s clear the watch is far more capable than standards might suggest. If that’s not enough though, you can always set about modifying the watch to improve its water resistance even further.

Using Heaters To Display Time

June 17, 2021 by Bryan Cockfield 9 Comments

We’re always fans of interesting clock builds around here, whether it’s a word clock, marble clock, or in this case a clock using a unique display method. Of course, since this is a build by Hackaday’s own [Moritz v. Sivers] the display that was chosen for this build was a custom thermochromic display. These displays use heat-sensitive material to change color, and his latest build leverages that into one of the more colorful clock builds we’ve seen.

The clock’s display is built around a piece of thermochromic film encased in clear acrylic. The way the film operates is based on an LCD display, but using heat to display the segments. For this build, as opposed to his previous builds using larger displays, he needed to refine the method he used for generating the heat required for the color change. For that he swapped out the Peltier devices for surface mount resistors and completely redesigned the drivers and the PCBs around this new method.

Of course, the actual clock mechanism is worth a mention as well. The device uses an ESP8266 board to handle the operation of the clock, and it is able to use its wireless capabilities to get the current time via NTP. All of the files needed to recreate this are available on the project page as well, including code, CAD files, and PCB layouts. It’s always good to have an interesting clock around your home, but if you’re not a fan of electronic clocks like this we can recommend any number of mechanical clocks as well.

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Sunlight-Based Life Clock Predicts Your Darkest Hour

June 16, 2021 by Kristina Panos 9 Comments

The past year has been quite a ride for everyone on Earth. But you never know which day is going to be your last, so you might as well live a little, eh? This clock doesn’t actually know when you’ll kick off, either. But just for fun, it predicts the number of years remaining until you go to that hackerspace in the sky by hazarding a guess that’s based on your current age and the latest life expectancy tables. Don’t like the outcome? It’s completely randomized, so just push the button and get a set of numbers: the age you might die, and the percentage of life elapsed and remaining.

We love the design of this calculated doom clock, and it’s quite simple inside — an Arduino Pro Mini outputs the graph on an 2.9″ e-paper display, and both are powered with a 5.5 V solar panel. Just suction cup that puppy to the window and you’ll get automatic updates about your impending demise on sunny days, and none on cloudy days.

Want a more realistic picture of your mortality? Here’s a clock that counts down to your 80th birthday.

Historical Hackers: Ctesibius Tells Time

June 9, 2021 by Al Williams 11 Comments

People are obsessed with the time and the weather. We’ve talked about the weather since we were all cave dwellers hunting with spears. But the time is a different matter. Sure, people always had the idea of the passage of time. The sun rising and setting gives a natural sense of days, but daylight and dark periods vary by the time of year and to get an accurate and linear representation of time turns out to be rather difficult. That is unless you are a Greek engineer living in Alexandria around 250 BC.

Legend has it that and engineer working in his father’s barbershop led him to discover not only the first working clock, but also the pipe organ, launching the field of pneumatics in the process. That engineer was named Ctesibius and while his story is mostly forgotten, it shows he has a place as a historical hacker.

You might think there were timekeeping devices before 250 BC, and that’s sort of true. However, the devices before Ctesibius had many limitations. For example, a sundial can tell time, but only if the sun is shining. At night or during a storm it is worthless.

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Do Wristwatches Get Any Better Than A Cuckoo Clock?

June 5, 2021 by Jenny List 10 Comments

There are few better ways of asserting your independent spirit as a hardware hacker than by creating your own special timepiece. Even more so if the timepiece is a watch, particularly in this era of smartwatches. Few home-made timepieces though have come as near to wristwatch Nirvana as the cuckoo clock wristwatch from [Kiyotaka Akasaka], which we would venture to name as having won wristwatches. Nobody will top this one in the field of home-made clocks!

Superlatives aside, this is an electronic cuckoo clock on the wrist, with an LED ring dial and a motorised cuckoo, all clothed in an authentically rustic tiny wooden cuckoo clock case. It communicates via BLE with a smartphone, and even has a sound channel for a cuckoo sound. Frustratingly there’s little in the way of detail about the electronics themselves, but we’re guessing that almost Bluetooth-capable microcontroller could be pressed into service. Take a look at the video below the break.

So we’ve established that it’s a cuckoo clock wristwatch, and that we like it, a lot. It is however not the only novelty cuckoo clock we’ve brought you.

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Retro Useless Clock Eventually Shows You The Time

June 3, 2021 by Kristina Panos 8 Comments

It’s true; hackers like clocks. And hackers like useless machines. But would they like an intersection of the two? We’re thinking yes, probably, though we would argue that this QR clock was at no point fully useless. Yes, a QR clock as in, whip out your phone and, ignoring the conveniently-available phone time, open the bar code reader so you can check the time on this thing. So, it’s semi-useless. But at least it doesn’t detect cameras and then hide the QR code. That would be evil.

This project started life as a display piece for the hex wall down at [megardi]’s hackerspace, but, state of the world being what it is, [megardi] hasn’t made it down there yet. And meanwhile this little guy was looking cuter and cuter, so [megardi] decided to make him more useful and freestanding. The ESP32 inside gets the official time from NIST and displays it on the 1.5″ OLED screen. It also has a single alarm now, along with some other non-QR code clock faces that display the time in various ways.

We really like the look of this clock. Honestly, with those uniform tics around the edge, it sort of reminds us of the doomsday clock — you know, the ‘minutes to midnight’ quarter clock face that shows the current perceived threat level of how close we are to destroying the world with the technologies we’ve created. That clock is kind of cute, too, which is a little bit weird considering what it represents.

Speaking of our delicate planet, here’s a gorgeous little Earth clock that casts a shadow on whatever slice of the planet is currently shrouded in darkness.

Persistent Displays With UV Light

May 24, 2021 by Jenny List 52 Comments

This year’s Hackaday Prize has “Rethink Displays” as one of its first theme, and [Tucker Shannon] has given us his best shot on that subject with a set of impressive displays that “write” on glow-in-the-dark material using ultra-violet light. These materials glow for a while after UV illumination, so moving a light source like a UV LED over the surface draws glowing text or simple graphics which can be readily consumed.

One of the examples this a clock we were first smitten with back in 2018. It is a rather attractive 3D-printed affair with those servos mounted below the screen that moves a UV LED through a pair of linkages. Other offerings that play on the same UV stylus medium include a laser on an az-el mount controlled by a Raspberry Pi Zero. It’s a neat idea very effectively done, and we can see it has a lot of potential.

But the most impressively advanced so far is the model shown in the image at the top of the article and the demo video at the bottom. A loop of phosphorescent material is the display surface itself. This one moves that loop with two rollers to make up the X axis, and moves the UV source up and down for the Y axis. As with all of these designs, whatever is written will soon fade, leaving the surface ready for the next bit of information.

Interested in this project and think you could do a display of your own? The Hackaday Prize 2021 is live, and we’d love to see you enter it!

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