ESP32 LED Eyes Help Keep Toddler In Bed

We’ve seen a lot of custom clocks here at Hackaday, many of which have pushed the traditional definition of the timepiece to its absolute limit. But for all their wild designs, most of them do have something in common: they assume you can actually read a clock and understand the concept of time. But what if you’re developing a clock for a toddler who’s only just coming to terms with such heady ideas?

The answer, at least for [Riley Parish] is a set of 3D printed eyes that are illuminated with either yellow or green LEDs depending on whether or not it’s time to get out of bed. More than just the color of the light, the eye design (which is embedded into the rear of the front panel) switches between wide-open and tightly shut depending on the time of day.

Internally the device is very simple, with the 5 mm LEDs and their associated resistors connected directly to the digital out pins on an ESP32 development board. While the dual-core microcontroller is admittedly pretty overkill for flipping some LEDs every 12 hours or so, the firmware does at least pull the current time from NTP — plus the powerful MCU offers plenty of room to grow. A web front-end to configure the device or check its current status would only be a few more lines of code.

As it so happens, this isn’t the first toddler timepiece to grace these pages. Perhaps unsurprisingly, those previous examples also used changing color to help indicate the passage of time.

Faceless Clock Makes You Think Twice About How It Works

We love projects that make you do a double-take when you first see them. It’s always fun to think you see one thing, but then slowly realize everything is not quite what you expected. And this faceless analog clock is very much one of those projects.

When we first saw [Shinsaku Hiura]’s “Hollow Clock 4,” we assumed the trick to making it look like the hands were floating in space would rely on the judicious use of clear acrylic. But no, this clock is truly faceless — you could easily stick a finger from front to back. The illusion is achieved by connecting the minute hand to the rim of the clock, and rotating the whole outer circumference through a compact 3D printed gear train. It’s a very clever mechanism, and it’s clear that it took a lot of work to optimize everything so that the whole look of the clock is sleek and modern.

But what about the hour hand? That’s just connected to the end of the minute hand at the center of the clock’s virtual face, so how does that work? As it is with most things that appear to be magical, the answer is magnets. The outer rim of the clock actually has another ring, this one containing a pair of neodymium magnets. They attract another magnet located in the very end of the hour hand, dragging it along as the hour ring rotates. The video below shows off the secrets, and it gives you some idea of how much work went into this clock.

We’re used to seeing unique and fun timepieces and other gadgets from [Shinsaku Hiura] — this up-flipping clock comes to mind, as does this custom RPN calculator — but this project is clearly a step beyond.

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Digital Hourglass Counts Down The Seconds

If someone asked you to build a digital hourglass, what would your design look like? [BitBlt_Korry] took on that challenge, creating a functional art piece that hits it right on the nose: an hourglass with a digital display

Iron filings fall between two pieces of plexiglass while ghostly numbers appear, counting down 30 seconds. Just as quickly as they appear, the numbers disappear – dropping down to the bottom of the enclosure. Each second is punctuated by what might be the loudest clock tick we’ve ever heard.

Of course, it’s not all magic. The hourglass is controlled by a Raspberry Pi Pico running code in MicroPython. The pico drives a series of transistors, which in turn are used to control 14 solenoids.  The solenoids serve double duty — first, they move pieces of flat “fridge magnet” material close enough to attract iron filings. Their second duty is of course provide a clock tick that will definitely get your attention.

Tilt sensors are the user input to the hourglass, letting the Pi Pico know which end is up when it’s time to start a new 30-second countdown.

[BitBlt_Korry] mentions that the hardest part of the project was setting the screws at the top and bottom of the hourglass to get the perfect uniform flow of iron filings. 

[BitBlt_Korry] calls his creation “「時場(じば)」”.  Google translates this to “Jiba”, which means “magnetic field”.  We’re not native speakers, but we’re guessing there is a double meaning there.

This isn’t the first time we’ve seen humble iron filings stand up and dance at our command. If iron dust is too dry a topic, we’ve got plenty of ferrofluid projects as well!

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A cyclotron clock display, mounted on a wooden base. There are two stepper motors exposed on either side. There is a panel installed in the wooden base with a red button on the left, two knobs and four smaller buttons in a two by two grid on the right.

A Flipping, Perpetually-Rotating Clock

Clocks are a mainstay of hackers and makers, as they provide a way to explore creative designs while still maintaining a functional aspect to the project. [Brett Oliver] follows this tradition in making a cyclotron clock that uses a perpetual rotating digit concept from a 1900s desk flip calendar.

An exploded view of one of the flip calendar digit display, showing how the tiles fit into the chamber.

Each digit of the clock has a rotating chamber that’s big enough to fit a group of tiles inside that have digits printed on either face. The tiles are sized and stacked in such a way that the rotation of the chamber allows the next tile to slide in front of the old one. Specific digits are revealed by rotating the chamber a number of times.

Each of the four digits positions has a 28BYJ-48 stepper motor to rotate the chamber, with each motor being driven by a ULN2003 driver module. The main microcontroller is a ESP32 WROOM, and an I2C compatible DS3231 real time clock (RTC) module keeps time. All of the motors are driven off of an LM2596 module that provides 7 V, while the ESP32 and RTC are powered from a USB connector.

The different modes and the ability to set time is done through a panel that has various buttons and knobs. The whole clock is mounted on a custom wooden base that has cutouts for the panels and cabling. [Brett Oliver] has done a great job of documentation, going into detail about the mechanics and electronics of the build. Design files, including STLs of the various components, are also available for download. Be sure to check out the video after the break.

We’ve featured a flip calendar with a similar operating principle before which clearly shows the inner workings of the mechanism.

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Building A Tessellated NeoPixel Clock

Anyone can buy a clock, but building your own lets you express your creative flair along the way. [Edison Science Corner] did just that with this neat sci-fi looking design.

The build relies on an Arduino Pro Mini to run the show, paired with a DS3231 real-time clock module. The latter part is of great importance, as without it, the Arduino would not keep accurate time. The 3D printed enclosure looks nondescript from the outside. However, inside, it’s got a neat triangular structure which allows the time to be displayed in that attractive tessellated triangular fashion. There’s a black plastic separator between all the segments which stop unattractive bleed-through and really help with the final effect. The individual triangles are each lit by a NeoPixel LED, which are both addressable and capable of lighting up in RGB colors. It makes for an attractive and colorful display.

If you want to try something more traditional yet challenging, consider whipping up your own 7-segment displays. Video after the break.

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battery powered wall mounted clock with LCD display and 10 capacitive touch buttons

A Peppy Low Power Wall Mounted Display

[Phambili Tech] creates a battery powered mountable display, called “the Newt”, that can be used to display information about the time, calendar, weather or a host of other customizable items.

The Newt tries to strike a balance between providing long operating periods while still maintaining high refresh rates and having extensive features. Many of the battery powered devices of this sort use E-Ink displays which offer long operating windows but poor refresh rates. The Newt uses an LCD screen that, while not being as low power as an E-Ink display, offers extended battery operation while still being daylight readable and providing high refresh rates.

The display itself is a 2.7 inch 240×400 SHARP “Memory In Pixel” LCD that provides the peppy display at low power. The Newt is WiFi capable through its ESP32-S2-WROVER module with a RV-3028-C7 Real Time Clock, a buzzer for sound feedback and capacitive touch sensors for input and interaction. A 1.85Wh LiPo battery (3.7V, 500mAh) is claimed to last for 1-2 months, with the possibility of using a larger battery for longer life.

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Digital Light Pipes Clock various view of seven-segment display using illuminated light-pipes

LED Clock Has Its Pipes On Display

For most hackers and makers, building a clock is a rite of passage. Few, though, will be as unusual and engaging as this design by [TerraG2].

By combining addressable LEDs, light pipes and 7-segment displays, [TerraG2] has built a timepiece that looks great and will surely be a great conversation starter as well. It’s packed full of features such as automatic brightness control, an accelerometer controlled user interface, and WiFi to make sure it’s always accurate.

partial rear view of the clock showing illuminated light pipes
Partial rear view of the clock showing illuminated light pipes

The decision to leave the light pipes visible behind the main display really makes the project stand out from other clock builds, and the methods [TerraG2] has used to achieve this look will no doubt be transferable to a host of other projects.

The LEDs are courtesy of a standard 8×8 RGB matrix, with a custom 3D-printed shroud to hold the light pipes in place and a clever connector at the other end to illuminate the segments. With two LEDs per segment, seven segments per digit, and four digits, there’s even room for some extra features down the line if you can think of a use for those eight spare LEDs.

The brain of the project is an ESP8266 D1 with an MPU6050 inertial measurement unit (IMU) to detect when it’s flipped over to change the color scheme.

Full documentation is on Github, and a video of the clock in use is after the break.

Light pipes have been used to great effect in some other clock projects we’ve seen, such as this modern Nixie clock and this “clock of clocks”, as well as in this light organ that we showed recently.

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