Author: Zoe Skyforest

3683 Articles

A More Convenient IButton Reader

June 24, 2026 by 3 Comments

iButtons are microchips housed in small, round, metal containers, and are similar to coin cell batteries in appearance. Among other things, they’re used for logging data in industrial contexts, particularly where it’s desirable to track parameters like temperature over time. [Geoffrey Wells] has worked with these sensors, and decided that the aging solutions for reading these devices are too cumbersome and out-of-date. Thus, he designed ChillPoint as a more modern solution.

As you might have guessed by the name, [Geoffrey] was inspired to build a rig specifically for inspecting iButton data loggers in cold chain logistics applications. It’s built around an ESP32-C6, which has a 1-Wire probe on the front for communicating with the target device. On contact, the reader dumps all the data, storing it on its own flash storage. The data can then further be accessed by connecting to the ChillPoint handheld device over its own WiFi access point, upon which it hosts a web UI for access. The handheld can be used for scanning iButtons single-handed, while a smartphone, tablet, or laptop can be used as a screen to monitor the results live.

The project is nearing completion, and [Geoffrey] says both the hardware and software will be open source once it’s all said and done. Anyone interested in adding a ChillPoint to their toolbox should keep an eye out for its upcoming CrowdSupply campaign.

If you find yourself working with these devices on the regular, this project may be appealing to you. We’ve looked at iButtons many times over the years. The Java Ring was probably the coolest.

Laser Scanning A Cave With Homebrew Gear

June 24, 2026 by 10 Comments

How do you measure the inside of a cave? You could do a bunch of hard work with classic surveying gear… or you could just use a laser scanner. [9nl] did the latter, with a scanning rig of his own creation.

The build is based around an Ouster VLP-16 mid-range lidar sensor. It shoots out pulses of light and measures how long it takes them to bounce back in order to determine the range of objects in the vicinity, and thus can be used to great effect for 3D scanning tasks. For [9nl], though, the sensor had a serious limitation. Since it only had a 40-degree field of view, it wasn’t ideal for the desired application of scanning a cave. However, by building a custom rig that could rotate the sensor, [9nl] ended up with a rig that could 3D scan an area through a full 360 degrees. There’s nothing wildly complex involved, just some good old mechanical engineering—putting the sensor on a shaft and spinning it with a belt drive. Then it’s just a matter of processing the data correctly. The hard part is then getting the rig in and out of the cave without breaking anything.

There are plenty of off-the-shelf 3D scanning solutions that can do this work, but few of them come cheap. Plus, rolling your own teaches you a great many things as you hone your solution to your particular needs. Video after the break.

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VFD Clock Runs On A Single AA

June 24, 2026 by 3 Comments

There are lots of different ways to build a clock. [Sciter_] came into the possession of some old calculator parts, and decided to reuse them for just such a project.

The heart of the build is an ATmega328P microcontroller, running off of a 32.768 kHz crystal. This allows the chip’s counters to neatly divide down the frequency to get a steady 1 Hz pulse for accurate timekeeping. Time is displayed on a vacuum fluorescent display (VFD) harvested from an old calculator. These displays need rather high voltages to run, which in this case are produced by a HV5812 driver chip and supporting circuitry. The display itself is neatly cradled in a pair of copper pipe elbows for a stylish look, with some addressable RGB LEDs present to provide some charming underglow.

Power for the device comes from a single AA battery, using a transformer-based low voltage converter. Alternatively, it can run off a USB 5 V power supply, which also charges the NiMH AA cell while available with the aid of an LM2576-ADJ buck converter.

Overall, it’s a neat homebrew clock that taught [Sciter_] plenty during its construction, and not the first time we’ve seen somebody put together a clock with second-hand VFDs. If you’re finding fun ways to reuse old display tech, don’t hesitate to let us know on the tipsline.

The Trains With Rubber Tires

June 24, 2026 by 37 Comments

The train was one of the game-changing inventions that defined the Industrial Age. No more would humanity rely on tempestuous animals to haul goods and passengers great distances across the land. Fire and steam came along to rapidly increase the speed of travel and transformed the very fabric of society itself.

To this day, the vast majority of train networks rely on the same basic principle—heavy locomotives and carriages running steel wheels on steel tracks. Yet, there is a curious alternative twist on this concept that sees trains of carriages riding on tires instead. But what would possess anyone to build a rubber tired train?

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A T9 Keyboard For Your Smartphone

June 24, 2026 by 15 Comments

These days, most of us are fortunate enough to use smartphones with decent touchscreen keyboard capabilities. However, once upon a time, if you wanted to type something on a phone, you had to tap it out on the number keys instead. [Jarrett] is bringing that back with a custom T9 keyboard for modern phones. 

The build is designed around the keypad of the Nokia E52, a Symbian smartphone released in 2009—two years after Apple changed the game with the first iPhone. The phone keypad itself is laid over a custom PCB with Alps SKRK tactile switches corresponding to each individual key. Each is wired with a diode and the switches are scanned as a row/column array as is typical for keyboards. Reading the matrix is an ESP32-C6 microcontroller, which counts the keypresses and spits out the right letters over its Bluetooth connection to an attached smartphone or other device. Power is via a small lithium-ion battery, looked after by a TP4200 charger chip.

Overall, the keyboard works as you’d expect, allowing T9-style input to any compatible device that works with Bluetooth keyboards. [Jarrett] does have one regret, with the 0.98 N actuation force switches used leaving he keypad feeling a little mushy. The firmer 1.57 N switches were suspected to give a more satisfying response under thumb, which was a nice upgrade in the second revision build.

We’ve seen other builds in this vein before, too, albeit with bigger keys. If you’re coming up with your own esoteric input methods, don’t hesitate to notify the tipsline.

Tricking A Bike Counter

June 20, 2026 by 84 Comments

Some municipalities implement bike counters on cycling routes in order to monitor traffic. [nullpxl] recently investigated how these counters work, and explored methods that can be used to trick the counter into thinking a bike passed over it.

A great many of these devices are built using inductive loop sensors. This involves passing a current through a loop of wire embedded in the ground. When a conductive item such as the metal wheel of a bike passes through the electric field, eddy currents are generated in the item, creating their own magnetic field which reacts with the loop’s field itself. This creates a change in inductance which can be measured, and thus used to log the number of times a conductive item has passed over the sensor. By looking at the signature of the inductance change, a system can be tuned to detect specific objects—for example, two bicycle wheels passing over a sensor will create a signal that varies over time in a characteristic way.

[nullpxl] first tried to recreate a “bike” signal for the inductive loop by running over the area holding two metal pans. This wasn’t close enough, so a new idea was needed. Experiments with a scrap bike then indicated that there was a speed gate involved, and that wheeling one wheel over the sensor and back again could trick the sensor into thinking a bike had passed by. Eventually, [nullpxl] distilled all this learning down to create “the BIKE BASKET.” It’s simply a bag with a bike wheel in it, and swinging it over the sensor twice makes the counter tick up.

Is there any money in tricking the average municipal bike counter in your local city? We doubt it, unless Big Bike is getting increasingly filthy in its lobbying efforts. In any case, we love to see weird sensor hacks around these parts. Continue reading “Tricking A Bike Counter” →

Making Old Computers Count To A Million

June 19, 2026 by 10 Comments

How fast can you count to a million? It would probably take you a while. A computer could certainly do it faster. Indeed, the The National Museum of Computing figured it could actually prove to be a simple but useful benchmark for comparing computers over many eras and architectures. Thus was born the Million Measure.

The intention was to develop a benchmark that could run on just about anything considered a “computer.” As explained in a recent talk, the Million Measure can be run quite simply on anything from an ancient World War II computer like Colossus, to a modern Raspberry Pi. There are no complicated algorithms that need optimization, nor architecture-specific code required to do the job. The museum also found it to be a useful way to figure out which computers in their collection were actually working at any given time. Early computers from the mid-20th century reported benchmark times in minutes, while a 1995 BeBox is the fastest machine tested so far at 0.004 seconds.

It’s not a particularly useful measure for modern machines, which are so fast as to make the test difficult to parse in an intuitive way. But if you’re working with today’s hardware, there are other techniques you can use. Video after the break.

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