A new display wedged into a car-based fridge

New Brains Save 12 V Fridge From The Scrap Heap

March 14, 2024 by Dave Rowntree 17 Comments

Recently [nibbler]’s Evakool 55L vehicle fridge started to act strangely, reporting crazy temperature errors and had no chance of regulating. The determination was that the NTC thermistor was toast, and rather than trying to extricate and replace this part, it was a lot easier to add a new one at a suitable location

A straight swap would have been boring, so this was a perfect excuse for an overboard hack. Reverse engineering the controller wouldn’t be easy, as the data wasn’t available, as is often the case for many products of this nature.

While doing a brain transplant, the hacker way, we can go overboard and add the basics of an IoT control and monitoring system. To that end, [nibbler] learned as much as possible about the off-the-shelf ZH25G compressor and the associated compressor control board. The aim was to junk the original user interface/control board and replace that with a Raspberry Pi Pico W running CircuitPython.

For the display, they used one of the ubiquitous SH1106 monochrome OLED units that can be had for less than the cost of a McDonald’s cheeseburger at the usual purveyors of cheap Chinese electronics. A brief distraction was trying to use a DS18B20 waterproof thermometer probe, which they discovered didn’t function, so they reverted to tried and trusted tech — a simple NTC thermistor.

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Custom Mouse-Making: Clay Is The Way

March 10, 2024 by Kristina Panos 11 Comments

For something that many of us handle all day long, it sure would be nice if mice came in more sizes and shapes, wouldn’t it? Until that day, we’ll just have to find something passable or else design and build a custom-shaped mouse from scratch like [Ben Makes Everything] did.

First, [Ben] played around with some modelling clay until he had a shape he was happy with, then took a bunch of pictures of it mounted on a piece of wood for easy manipulation and used photogrammetry to scan it in for printing after cleaning it up in Blender. About six versions later, he had the final one and was ready to move on to electronics.

That’s right, this isn’t just mouse guts in an ergonomic package. Inside is Arduino Pro Micro and a PMW 3389 optical sensor on a breakout board. [Ben] was going to use flexible 3D printed panels as mouse buttons, but then had an epiphany — why not use keyboard switches and keycaps instead? He also figured he could have two buttons per finger if he wanted, so he went with Kailh reds for the fingers and and whites in the thumb.

Speaking of the thumb, there was no room for a mouse wheel in between those comparatively huge switches, so he moved it to the the side to be thumb-operated. [Ben] got everything working, and after all this, decided to make it wireless. So he switched to an Adafruit Feather S3 and designed his first PCB for both versions. Ultimately, he found that the wireless version is kind of unreliable, so he is sticking with the wired one for now.

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Educational Arduino Clock Uses Analog Meters For Display

March 1, 2024 by Lewin Day 13 Comments

When it comes to educational electronic projects, it’s hard to go past building a clock. You learn tons about everything from circuit concepts and assembly skills to insights about the very nature of time itself. And you get a clock at the end of it! [hamblin.joe] wanted to do a simple project for kids along these lines, so whipped up a neat design using analog meters to display the time.

The build relies on that old stalwart, the Arduino Uno, to run the show. It’s hooked up to a DS3231 real-time clock module so it can keep accurate time for long periods, as is befitting a clock. Displaying the time is done via the use of two analog meters, each fitted with a custom backing card. One displays hours, the other, minutes. The analog meters are simply driven by the PWM outputs of the Arduino.

It’s not a hugely complex project, but it teaches so much. It provides an opportunity to educate the builders about real-time clocks, microcontroller programming, and even the concepts behind pulse width modulation. To say nothing of the physical skills, like learning to solder or how to assemble the laser-cut enclosure. Ultimately, it looks like a really great way for [hamblin.joe] and his students to dive into the world of modern electronics.

Bringing Modern Technology To A Sled

February 12, 2024 by Bryan Cockfield 17 Comments

Street sledding, a popular pastime in Norway, is an activity that is slowly dwindling in popularity, at least as far as [Justin] aka [Garage Avenger] has noticed. It used to be a fun way of getting around frozen lakes and roads during winter, and while some still have their sleds [Justin] wanted to see if there was a way to revitalize one of these sleds for the modern era. He’s equipped this one with powerful electric turbines than can quickly push the sled and a few passengers around the ice.

Since this particular sled is sized for child-sized passengers, fuel-burning jet engines have been omitted and replaced with electric motors that can spin their turbine blades at an impressive 80,000 rpm. The antique sled first needed to be refurbished, including removing the rust from the runners and reconditioning the wood. With a sturdy base ready to go, the sled gets a set of 3D printed cowlings for the turbines, a thumb throttle on the upgraded handlebars, and a big battery with an Arduino to bring it all together.

With everything assembled and a sheet of ice to try it out on, the powerful sled easily gets its passengers up to the 20-30 kph range depending on passenger weight and size. There’s a brake built on an old ice skate for emergency stops, and the sled was a huge hit for everyone at the skating pond. There are plenty of other ways to spruce up old sleds, too, like this one which adds a suspension for rocketing down unplowed roads.

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Give Your Projects A Retro Tint With This 8051-based Arduino Uno

February 5, 2024 by Julian Scheffers 37 Comments

Most of us are familiar with the Arduino Uno, a starting place for electronics projects since 2010. But what if the Arduino Uno was released in 1980? You’d probably get something like [ElectroBoy]’s 8051-based Arduino Uno.

28-pin DIP integrated circuit with a window revealing the die — Close-up shot of the 87C752, an 8051 with EPROM

The Arduino Uno-compatible board has an MCS-51 (often called 8051 instead) instead of the usual ATmega328P/ATmega168. Specifically, [ElectroBoy] uses the AT89S52. Like the ATmega microcontrollers, the AT89S52 has an 8-bit CPU with a Harvard architecture and very similar GPIO capabilities. Unlike the ATmega, however, the original MCS-51 has a CISC CPU (as opposed to ATmega being RISC) and a release date about 36 years earlier.

The board itself also has some differences from the original Arduino Uno. First of all, it has a USB type-C port, which is definitely a bonus. Secondly, it’s simpler: No USB-UART (which also means no USB programming), a different pin layout (Arduino shields likely won’t fit) and more I/Os than the ATmegas have. Sure, it’s not as practical as an actual Arduino Uno, but it’s definitely cool for our retrocomputing nerds.

Learn Sailing Mechanics Without Leaving Dry Land

January 20, 2024 by Danie Conradie 31 Comments

The ancient art of sailing can be very intimidating for the uninitiated given the shifty nature of wind. To help understand the interaction of wind direction and board orientation, [KifS] designed a hands-on sailing demonstrator that lets students grasp the basics before setting foot on a real sailboat.

The demonstrator uses a potentiometer as a tiller to control a model sailboat’s angle, while another stepper motor adjusts the position of a fan to simulate changing wind directions. With an Arduino Uno controlling everything, this setup affords students the opportunity to learn about sail positioning and adjusting to shifting winds in an interactive way, without the pressures and variables of being on the water.

[KifS]’s creation isn’t just about static demonstrations. It features four modes that progressively challenge learners—from simply getting a feel for the tiller, to adjusting sails with dynamic wind changes, even adding a game element that introduces random wind movements demanding quick adjustments. [KifS] mentions there are potentials aspects that can be refined, like more realistic sail response and usability, but it already achieved the main project goals.

There are a myriad of potential ways to add new tech to the ancient art of sailing. We’ve seen a DIY autopilot system, full sensor arrays, and an open source chart plotter. It’s even been proven you can have a wind powered land vehicle that travels faster than the wind.

Don’t Panic: A Cooperative Bomb Defusing Game

January 18, 2024 by Kristina Panos 5 Comments

[Heath Paddock] wanted to confound his friends with a game that mimics an escape room in a box. About six months after starting, he had this glorious thing completed. It’s a hardware version of a game called Keep Talking and Nobody Explodes where players have five minutes to defuse a suitcase bomb. This implementation requires at least two players, one with the box-bomb itself, and one who holds all the knowledge but can’t see the box-bomb to defuse it.

[Heath]’s version has twice as many modules as the original game, each hand-wired one driven by an Arduino. One of the modules is an LED maze. There are two green anchor LEDs in one of six configurations, and and blue and a red LED.

The object is to move the blue LED next to the red one without touching any walls. Of course, the box-holder can’t see the walls and must describe the configuration of the anchor LEDs to their partner in order to get started.

All of the modules are quite different, which likely makes for an extremely fun and challenging five minutes. [Heath] reports that getting inter-module communication down was a long road. Eventually, [Heath] settled on a mesh network configuration and connected everything in a big loop. Be sure to check out the walk-through video after the break.

This isn’t the first time we’ve seen a hardware implementation of this game. Here’s one that uses a Raspberry Pi.

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