2025 One-Hertz Challenge: Clock Calibrator

July 28, 2025 by Lewin Day 8 Comments

Wall clocks! Are they very accurate? Well, sometimes they are, and sometimes they lose minutes a day. If you’ve got one that needs calibrating, you might like this device from [Lauri Pirttiaho].

Most cheap wall clocks use very similar mechanisms based around the Lavet-type stepper motor. These are usually driven by a chip-on-board oscillator that may or may not be particularly accurate.

[Lauri] desired a way to tune up these cheap clocks by using GPS-level timing accuracy. Thus began a project based around a CY8KIT evaluation board from Cypress. The microcontroller is paired with a small character LCD as a user interface, and hooked up to a cheap GPS module with an accurate 1-pulse-per-second (1PPS) timing output. The concept is simple enough. Clock drift is measured by using counters in the microcontroller to compare the timing of the GPS 1PPS output and the pulses driving the Lavet-type stepper motor. The difference between the two can be read off the device, and used to determine if the wall clock is fast or slow. Then one need only use a trimmer capacitor to tweak the wall clock’s pulse rate in order to make it more accurate.

Few of us spend much time calibrating low-cost wall clocks to high levels of accuracy. If that sounds like a fun hobby to you, or your name is Garrus, you would probably find [Lauri]’s device remarkably useful. Believe it or not, this isn’t the first clock calibrator we’ve seen, either. Meanwhile, if you’ve brewed up your own high-accuracy timing hardware, feel free to let us know on the tipsline.

2025 One-Hertz Challenge: Shadow Clock

July 26, 2025 by Lewin Day No comments

You can buy all kinds of conventional clocks that have hands and numbers for easy reading. Or, like [Fabio Ricci], you could build yourself something a little more esoteric, like this neat shadow clock.

The heart of the build is an ESP8266 microcontroller, which gets the current time via Wi-Fi by querying an NTP time server. It also uses a DS3231 real-time clock module as a backup, keeping accurate time even when a network connection is unavailable.

Time is displayed via a 60-pixel ring of WS2812B addressable LEDs. These 60 LEDs correspond to the usual per-minute graduations that you would find on a regular clock. Current hour is displayed by lighting the corresponding LED red, while minutes are shown in blue and seconds in white. It’s called a “shadow clock” because of its method of activation. IR distance sensors are used to activate the time display when a hand or finger is placed near the clock. As Fabio puts it, “shadow play” will make the clock display the time. Otherwise, it switches to be a simple round device on the wall that displays colorful animations.

It’s a neat build that looks quite unassuming as a decor piece, and yet it also serves as an easy-to-read timepiece. We’ve seen LEDs put to all sorts of good uses in clock builds around these parts. Meanwhile, if you’ve found your own unique way to display the time—either in readable fashion, or totally oblique—don’t hesitate to let us know.

2025 One-Hertz Challenge: A Clock Sans Silicon

July 26, 2025 by Lewin Day 12 Comments

Just about every electronic device has some silicon semiconductors inside these days—from transistors to diodes to integrated circuits. [Charles] is trying to build a “No-Silicon digital clock” that used none of these parts. It looks like [Charles] is on the way to success, but one might like to point out an amusing technicality. Let’s dive in to the clock!

Instead of silicon semiconductors, [Charles] is attempting to build a digital clock using valves (aka tubes). More specifically, his design relies on seven dekatrons, which are the basic counting elements of the clock. By supplying the right voltages to the various cathodes of the dekatrons, they can be made to step through ten (or sometimes twelve) stable states, used as simple memory elements which can be used as the basis for a timepiece. [Charles] will set up the first dekatron to divide down mains frequency by 5 or 6 to get down to 10 Hz, depending on whether the supply is 50 Hz or 60 Hz. The next dekatron will step down 10 times to 1 Hz, to measure seconds. The next two will divide by ten and six to count minutes, while a further two will divide the same way to create an impulse per hour. A final dekatron will divide by 12 to count the hours in a day.

Naturally, time will be displayed on Nixies. While silicon semiconductors are verboten, [Charles] is also considering the use of some germanium parts to keep the total tube count down when it comes to supporting hardware. Also, [Charles] may wish to avoid silicon, but here’s the thing about tubes. They use glass housings, and glass is made of silicon.

Cheeky technicalities aside, it’s a great project that promises to create a very interesting clock indeed. Progress is already steaming along and we can’t wait to see the finished product. We’ve seen dekatrons put to good use before, too. If you’re cooking up your own practical projects with mid-century hardware, don’t hesitate to let us know!

Listening To Ethernet Via Eurorack

July 26, 2025 by Lewin Day 9 Comments

Ethernet is how we often network computers together, particularly when they’re too important to leave on a fussy WiFi connection. Have you ever thought about listening to Ethernet signals, though? Well, you totally could, with the NSA selector from [wenzellabs].

The NSA selector is a Eurorack module, designed for use as part of a larger modular synthesizer. There are lots of fun jokes and references on the PCB, but the front panel really shows you what this module is all about. It’s got a pair of RJ45 jacks, ready to receive your Ethernet cables through which data is flowing. They’re paired with a single audio output jack. “Any bit on the network will be sent to the audio output,” [wenzellabs] explains.

The device operates in a relatively simple fashion. Network traffic from one jack is forwarded to the other, unmodified. However, it’s also spat out to a simple digital-to-analog converter and turned into audio. This thing doesn’t play digital audio formats or anything like that—it just turns raw Ethernet signalling into audible noise.

Raw signal noises might not sound very appealing, but let’s be real here. If you liked nice sounds, you wouldn’t be into Eurorack. Skip to 25:46 in the video below if you just want to hear the final product.

Continue reading “Listening To Ethernet Via Eurorack” →

Building A Color Teaching Toy For Tots

July 25, 2025 by Lewin Day No comments

Last year, [Deep Tronix] wished to teach colors to his nephew. Thus, he built a toy to help educate a child about colors by pairing them with sounds, and Color Player was born.

The build is based around the TCS34725, an off-the-shelf color sensor. It’s paired with an ESP32, which senses colors and then plays sounds in turn. [Deep Tronix] made this part harder by insisting on creating their own WAV playback system, using the microcontroller, an SD card, and its on-board digital-to-analog hardware.

The toy operates in three primary modes. Color-to-tone, color-to-sound, color-to-voice. Basically, a color is scanned, and then the Color Player creates a tone, plays back a pre-recorded audio sample, or spells out the name of the color that was just scanned.

[Deep Tronix] also included jolly mode, which just color cycles a few RGB LEDs. However, there’s a game inside jolly mode as well, created for an older nephew to play with. Enter the right button combination, and you unlock it. Then, the device suggests a color and you have to run around, find it, and scan it to score.

We love a good color game; somehow this build seems even more compelling than Milton Bradley’s classic Simon toy.

Continue reading “Building A Color Teaching Toy For Tots” →

Massive Aluminum Snake Casting Becomes Water Cooling Loop For PC

July 25, 2025 by Lewin Day 5 Comments

Water cooling was once only the preserve of hardcore casemodders and overclockers. Today, it’s pretty routinely used in all sorts of performance PC builds. However, few are using large artistic castings as radiators like [Mac Pierce] is doing.

The casting itself was inspired on the concept of the ouroboros, the snake which eats its own tail if one remembers correctly. [Mac] built a wooden form to produce a loop approximately 30″ tall and 24″ wide, before carving it into the classic snake design. The mold was then used to produce a hefty sand cast part which weighed in at just over 30 pounds.

The next problem was to figure out how to create a sealed water channel in the casting to use it as a radiator. This was achieved by machining finned cooling channels into the surface of the snake itself. A polycarbonate face plate was then produced to bolt over this, creating a sealed system. [Mac] also had to work hard to find a supply of aluminum-compatible water cooling fittings to ensure he didn’t run into any issues with galvanic corrosion.

The final product worked, and looked great to boot, even if it took many disassembly cycles to fix all the leaks. The blood-red coolant was a nice touch that really complemented the silvery aluminum. CPU temperatures weren’t as good as with a purpose-built PC radiator, but maxed out at 51 C in a heavy load test—servicable for [Mac]’s uses. The final touch was to simply build the rest of the PC to live inside the ouroboros itself—and the results were stunning.

We’ve featured a few good watercooling builds over the years. If you’ve found your own unique way to keep your hardware cool and happy, don’t hesitate to notify the tipsline!

Transparent PCBs Trigger 90s Nostalgia

July 25, 2025 by Lewin Day 42 Comments

What color do you like your microcontroller boards? Blue? Red? Maybe white or black? Sadly, all of those are about to look old hat. Why? Well, as shared by [JLCPCB], this transparent Arduino looks amazing.

The board house produced this marvel using its transparent flexible printed circuit (FPC) material. Basically, the stuff they use for ribbon cables and flex PCBs, just made slightly differently to be see-through instead of vaguely brown.

The circuit in question is a Flexduino, an Arduino clone specifically designed to work on flexible substrates. It looks particularly good on this transparent material, with the LEDs glowing and the white silkscreen for contrast. If you like what you see, you can order your own circuits using this material directly from JLCPCB’s regular old order form.

Most of all, this project reminds us of the 1990s. Back then, you could get all kinds of games consoles and other electronics with transparent housings. There was the beloved PlayStation Crystal, while Nintendo did something similar with the N64 while adding a whole line of tinted color and charcoal versions too. Somehow seeing a bit of the inside of things is just cool. Even if, in some cases, it’s just to avoid smuggling in prisons.

It took decades before you could get custom PCBs quickly and easily. Now, board houses are competing for the enthusiast (consumer?) market, and competition is spurring development of crazy stuff like transparent and even glow in the dark PCBs. What next? We’re thinking edible, ROHS and WEEE be damned. Drop your thoughts in the comments.

Thanks to [George Graves] for the tip!