7-Segment Digits Slide Stylishly on This OLED Clock

Over at Sparkfun, [Alex] shared an OLED clock project that’s currently in progress but has a couple interesting twists. The first is the use of a small OLED screen for each digit, to which [Alex] added a stylistic touch. Digits transition by having segments slide vertically in a smooth animated motion. It’s an attractive effect, and the code is available on his github repository for anyone who wants to try it out.

[Alex] also found that by using an ESP32 microcontroller and synchronizing the clock via NTP over WiFi, the added cost of implementing a real-time clock in hardware becomes unnecessary. Without an RTC, time would drift by a few seconds every day and require a reset. At the moment the clock requires the SSID and password to be hardcoded, but [Alex] would prefer to allow this to be configured via a web page and could use some help. If you have implemented a web server on the ESP32, [Alex] would like to know how you handled multiple pages. “I’ve been scratching my head throughout the build on how to get this done,” he writes. “With the ESP8266, there’s on(const String &uri, handler function), but that seems to have been removed on the ESP32.” If you can point [Alex] in the right direction, be sure to pipe up.

OLED displays and clocks often go together, as we have seen with projects like the DIY OLED Smart Watch, but it’s nice to see someone using the OLED’s strengths to add some visual flair to an otherwise plain display.

Word Clock Five Minutes At A Time

As this clock’s creator admits, it took far more than five minutes to put together, but it does display the time in five minute increments.

After acquiring five 4-character, 16 segment display modules that were too good to pass up, they were promptly deposited in the parts pile until [JF] was cajoled into building something by a friend. Given that each display’s pins were in parallel, there was a lot of soldering to connect these displays to the clock’s ATMega328P brain. On the back of the clock’s perfboard skeleton, a DS1307 real-time clock and coin cell keep things ticking along smoothly. The case is laser cut out of acrylic with an added red filter to up the contrast of the display, presenting a crisp, crimson glow.

Troubleshooting — as well as procrastination — proved to be the major stumbling block here. Each of the displays required extensive troubleshooting because — like Christmas lights of yore — one bad connection would cause all the other displays to fail. Furthermore, there isn’t any easy way to change the time, so the clock needs to be reprogrammed once in a while

We love word clocks because there are so many ways to configure them and for the oddities. That isn’t to say radial clocks are any less creative.

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Spell Out the Time with Frickin’ Laser Beams

Clocks are a never-ending source of fascination to hackers. We get all kinds around here, from Steampunk Nixie clocks to retro cool flip clocks to clocks that don’t even look like clocks. But this is something new — a glow-in-the-dark laser tracing clock.

What [tuckershannon]’s clock lacks in practicality it makes up for in the gee-whiz department. The idea is simple: trace the characters out on a phosphorescent screen using a laser. To accomplish this, [tuckershannon] adapted the design of this whiteboard marker robot clock, replacing the drawing surface with glow-in-the-dark stickers. A 405 nm laser diode module is traced over the surface by the two-servo pantograph plotter, charging up the phosphors. He offers no clue as to how long the ghostly image lingers, but from the look of it, we’d bet that it lasts for a good fraction of a minute, especially in a dark room. Then again, you’d want the image totally faded before the next write cycle comes up, to prevent overwriting the previous time.

All in all, it’s a nice design and a clever new clock display modality. And who knows — maybe this whole glowing phosphor display thing could really catch on.

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Get Inside a TCXO Clock Chip

[Pete] wondered how real-time clock modules could be selling on eBay for $1.50 when the main component, the Maxim DS3231 RTC/TCXO chip, cost him more like $4 apiece. Could the cheap modules contain counterfeit chips?

Well, sure they could. But in this case, they didn’t, and [Pete] has the die shots to prove it. He started off by clipping the SOIC leads rather than desoldering — he’s not going to be reusing this chip after he’s cut it in half. Next was a stage of embrittling the case by heating it up with a lighter and dunking it in water. Then he went at it with sandpaper.

It’s cool. You can see the watch crystal inside, and all of the circuitry. The DS3231 includes a TCXO — temperature-corrected crystal oscillator — and it seems to have a bank of capacitors that it connects and disconnects depending on the chip’s temperature to keep the oscillator running at the right speed. [Pete] used one in an offline situation, and it only lost sixteen seconds over a year, so we’d say that they work fine.

If you’d like to know more about how crystals are used to keep time, check out [Jenny]’s excellent article. And if sixteen second per year is way too much for you, tune up your rubidium standard and welcome to the world of the time nuts.

A New Battery For A Potted Clock Module

If you did much dismantling of PCs back in the 1980s and 1990s, you might be familiar with the Dallas Semiconductor range of potted real-time clock modules. These were chunky dual-in-line devices containing clock and non-volatile RAM chips, a crystal, and a lithium battery. The battery was good for about a decade, which was fine for most PCs of the day because the majority of desktop computers are replaced long before that deadline.

[Glitch], however has an industrial single-board computer with a 486 processor that has had a life much more prolonged than its desktop siblings due to its application. The battery in the onboard Dallas DS1387 has long ago expired, and since these devices are so long out of production to be unavailable, he’s had to improvise.

Improving on some previous documented projects he found through an internet search, he carefully ground away the potting compound to reveal a couple of the battery conductors, cut them with a PCB drill, and mounted a lithium cell holder on the top of the device with some tidily soldered Kynar wires to bring in the power. A CR1225 cell was used rather than the ubiquitous CR2032, as space was at a premium in the width of the ISA card form factor.

The potted RTC module is something of a rare device these days, but if you have a retro computer containing one this seems to be a very useful piece of work to bring it back to life. We’ve covered another similar one with a slightly larger battery in the past.

Linear Clock Slows the Fugit of the Tempus

We feature a lot of clocks here on Hackaday, and lately most of them seem to be Nixie clocks. Not that there’s anything wrong with that, but every once in a while it’s nice to see something different. And this electromechanical rack and pinion clock is certainly different.

[JON-A-TRON] calls his clock a “perpetual clock,” perhaps in a nod to perpetual calendars. But in our opinion, all clocks are perpetual, so we’ll stick with “linear clock.” Whatever you call it, it’s pretty neat. The hour and minute indicators are laser cut and engraved plywood, each riding on a rack and pinion. Two steppers advance each rack incrementally, so the resolution of the clock is five minutes. [JON-A-TRON] hints that this was a design decision, in part to slow the perceived pace of time, an idea we can get behind. But as a practical matter, it greatly simplified the gear train; it would have taken a horologist like [Chris] at ClickSpring to figure out how to gear this with only one prime mover.

In the end, we really like the look of this clock, and the selection of materials adds to the aesthetic. And if you’re going to do a Nixie clock build, do us a favor and at least make it levitate.

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Power Sipping Master Keeps Slave Clock on Time

Few things are as infuriating as clocks that are not synchronized. It’s frustrating when the clock on the range and the clock on the microwave act like they’re in time zones that are one minute apart. Now picture that same issue over dozens of clocks in a train station, or hundreds in a school or factory. It’s no wonder that slave clocks, which advance on signals from a master clock, were developed.

When a pair of vintage Lepaute slave clocks made their way to [melka], he knew just what to do – build his own master clock to keep the slave on track. This particularly stylish slave clock uses pulses of alternating polarity every 30 seconds and will work on 1.5-volt pulses, which let [melka] meet his design goal of running for a year off a single AA battery. To keep the power needs low, [melka] relies on the RTC to wake up the MSP430 every second to increment a counter. When it hits 30, a pulse is sent to the clock’s motor through an H-bridge; the MCU alternates the polarity of every other pulse to advance the clock.

It’s not immediately clear how the clock is set; we recall the slave clocks in high school rapidly advancing for Daylight Saving adjustments, so we assume [melka] has provided some way of pulsing the clock quickly to set the time. Regardless, it’s a good lesson in low-power design. And be sure to check out this PIC-based master clock replacement, too.