BLE Rain Gauge Sips Water And Batteries

February 3, 2025 by Al Williams 24 Comments

It isn’t that hard to make an electronic rain gauge if you have a steady source of power or you don’t mind changing batteries often. But [Matthew Ford] offers a third option: a simple device with a Bluetooth Low Energy (BLE) module that can get a few years of a pair of AA batteries.

The approach has several advantages. Batteries make the device self-contained, and changing them infrequently is an obvious win. In addition, the BLE allows the device to be wireless and send data directly to an Android device. Thanks to a WH-SP-RG rain gauge, there’s not much to that part. The smart part is an nRF52832 module and some minor parts. The phone side uses an off-the-shelf Android app.

In a project like this, it is critical to have timers that really put the CPU to sleep. [Matthew] had to modify the Arduino libraries to allow the lp_timer objects to make it to an hour. Without the modifications, the timer can only reach 8.5 minutes. Sure, you could stack them, but that means taking a power hit multiple times an hour which would affect battery life.

Not the most complex project, but more complexity would mean lower battery life, so — as they say — less is more. We couldn’t help but think that with rechargeable batteries and a small solar panel, this could last a very long time.

LoRa, of course, is another choice. You can make 3D print a tipping bucket device, too.

Antique-Style GPS Looks Like Steampunky Fun

February 1, 2025 by Zoe Skyforest 14 Comments

These days, turn-by-turn GPS navigation isn’t considered special anymore. It’s in every smartphone and most cheap rental cars, and thus everybody expects you to figure out where you’re going. If you want a simpler and less robust navigation experience, you might like to try the rather fancy RadioScout.

The RadioScout is a build from [hardlyhumanfx]—a group of engineers and artists that collaborate on fun and whimsical projects. It looks like some kind of steampunk compass, and it kind of is—but at heart, it’s powered by GPS.

You program the RadioScout using the buttons on the front panel and a rotary phone dial to enter the latitude and longitude of your destination. It then uses an internal GPS receiver to compare that with your current location, and calculates a direct bearing to where you want to go. This bearing is displayed with a large compass-like needle run by a stepper motor, and you you can use it to guide yourself onwards.

It’s an attractive build that uses lots of neat parts. The team interfaced a microcontroller with a GPS receiver, a rotary dial, and 7-segment LEDs for the latitude and longitude display. The very real bell is neat, too. The whole thing is wrapped up in a brass and wooden case that would make you a star at just about any sci-fi convention. The build video is a little vague on the finer details, but experienced makers will be able to figure out how it all works.

You can actually buy a RadioScout if it’s something you must have, but one suspects the Hackaday set would probably prefer the homebrew route.

Continue reading “Antique-Style GPS Looks Like Steampunky Fun” →

A light-up clock displays the day of the week.

What Day Is It Again? Check The Clock

January 22, 2025 by Kristina Panos 7 Comments

If you’re lucky enough to work from home, you’ll soon find that it presents its own set of challenges, mostly related to work/life balance. It can get so bad that you don’t know what day of the week it is. Really. Ask us how we know.

Rather than miss a meeting (or a day off), prolific hacker [Arnov Sharma] created this day of the week clock. It uses a customized LED driver board with seven sets of three LEDs, each driven by a MOSFET. Each MOSFET is controlled by a DFRobot Mini Beetle ESP32-C3. It runs on a 2200 mAh, 3.7 V lithium-ion battery.

While this is mostly PCBs, there are three printed parts that turn it into a displayable object. We really like the look of this clock — it has just the right amount of pizazz to it and reminds us of a and old movie marquee. Be sure to check out the great build instructions.

We love a good clock around here. In case you missed it, here is the latest from [Moritz v. Sivers] that uses a caustic lens to display the time.

Cyber Walkman Does It In Style

January 21, 2025 by Kristina Panos 20 Comments

One of the best things about adulthood is that finally we get to, in most cases, afford ourselves the things that our parents couldn’t (or just didn’t for whatever reason). When [Yakroo108] was a child, Walkmans were expensive gadgets that were out of reach of the family purse. But today, we can approximate these magical music machines ourselves with off-the-shelf hardware.

Besides the cyberpunk aesthetic, the main attraction here is the UNIHIKER Linux board running the show. After that, it’s probably a tie between that giant mystery knob and the super-cool GUI made with Tkinter.

We also like the fact that there are two displays: the smaller one on the SSD1306 OLED handles the less exciting stuff like the volume level and the current time, so that the main UNIHIKER screen can have all the equalizer/cyberpunk fun.

Speaking of, this user-friendly GUI shows play/stop buttons and next buttons, but it looks like there’s no easy way to get to the previous track. To each their own, we suppose. Everything is enclosed in a brick-like 3D-printed enclosure that mimics early Walkmans with orange foam headphones.

If you want an updated Walkman with keyboard switches (who wouldn’t?), check this out.

Time-of-Flight Sensors: How Do They Work?

January 20, 2025 by Al Williams 15 Comments

With the right conditions, this tiny sensor can measure 12 meters

If you need to measure a distance, it is tempting to reach for the ubiquitous ultrasonic module like an HC-SR04. These work well, and they are reasonably easy to use. However, they aren’t without their problems. So maybe try an IR time of flight sensor. These also work well, are reasonably easy to use, and have a different set of problems. I recently had a project where I needed such a sensor, and I picked up a TF-MiniS, which is a popular IR distance sensor. They aren’t very expensive, and they work serial or I2C. So how did it do?

The unit itself is tiny and has good specifications. You can fit the 42 x 15 x 16 mm module anywhere. It only weighs about five grams — as the manufacturer points out, less than two ping-pong balls. It needs 5 V but communicates using 3.3 V, so integration isn’t much of a problem.

At first glance, the range is impressive. You can read things as close as 10 cm and as far away as 12 m. I found this was a bit optimistic, though. Although the product sometimes gets the name of LiDAR, it doesn’t use a laser. It just uses an IR LED and some fancy optics.

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Stealth AirTag Broadcasts When Moved: An Experiment

January 18, 2025 by Heidi Ulrich 43 Comments

A simple yet intriguing idea is worth sharing, even if it wasn’t a flawless success: it can inspire others. [Richard]’s experiment with a motion-powered AirTag fits this bill. Starting with our call for simple projects, [Richard] came up with a circuit that selectively powers an AirTag based on movement. His concept was to use an inertial measurement unit (IMU) and a microcontroller to switch the AirTag on only when it’s on the move, creating a stealthy and battery-efficient tracker.

The setup is minimal: an ESP32 microcontroller, an MPU-6050 IMU, a transistor, and some breadboard magic. [Richard] demonstrates the concept using a clone AirTag due to concerns about soldering leads onto a genuine one. The breadboard-powered clone chirps to life when movement is detected, but that’s where challenges arise. For one, Apple AirTags are notoriously picky about batteries—a lesson learned when Duracell’s bitter coating blocks functionality. And while the prototype works initially, an unfortunate soldering mishap sadly sends the experiment off the rails.

Despite the setbacks, this project may spark a discussion on the possibilities of DIY digital camouflage for Bluetooth trackers. By powering up only when needed, such a device avoids constant broadcasting, making it harder to detect or block. Whether for tracking stolen vehicles or low-profile uses, it’s a concept rich with potential. We talked about this back in 2022, and there’s an interesting 38C3 talk that sheds quite some light on the broadcasting protocols and standards. Continue reading “Stealth AirTag Broadcasts When Moved: An Experiment” →

A PDA From An ESP32

January 18, 2025 by Jenny List 17 Comments

The ESP32 series of microcontrollers have been with us for quite a few years now and appeared in both Tensilica and RISC-V variants, both of which deliver an inexpensive and powerful device. It’s thus shown up in quite a few handheld computers, whether they be conference badges or standalone devices, and this is definitely a field in which these chips have more to give. We’re pleased then to see this e-ink PDA from [ashtf8], which we think raises the bar on this type of device.

At its heart is an ESP32-S3, on the back side of a QWERTY keyboard PCB, and for a display it has an e-ink screen. To get over the annoying e-ink refresh when typing text it uses a hybrid of e-ink and OLED, with a small OLED holding the current line which can be periodically sent to the e-ink. Perhaps the nicest thing about the hardware though is the clear resin printed clamshell case, and a hand-cast silicone membrane for the keyboard. That has always been a part considered difficult to produce, and here he is making one from scratch. Take a look at the video below the break.

Software-wise it has a range of apps with more promised, but even as it stands it looks useful enough to work with. If that’s not enough, then perhaps an ESP32 operating system would help.

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