Baffle The Normies With This Binary Thermometer

June 8, 2024 by Dan Maloney 9 Comments

We think it’s OK to admit that when someone puts a binary display on a project, it’s just a thinly veiled excuse to get more blinkenlights into the world. That and it’s a way to flex a little on the normies; you’ve gone pretty far down the tech rabbit hole to quickly decipher something like this binary-display thermometer, after all.

Don’t get us wrong, we think those are both perfectly valid reasons for going binary. And all things considered, a binary display for a thermometer like [Clovis Fritzen]’s is much simpler to decode than, say, a clock. Plus, it seems a bit that this build was undertaken at least partially as an exercise in Charlieplexing, which [Clovis] uses to drive the six-bit LED display using only three lines of GPIO from the Digispark ATtiny85 board running the show.

The temperature sensor is a DHT11, whose output is read by the microcontroller before being converted to binary and sent to the six-bit display. The 64-degree range is perfect for displaying the full range of temperatures most of us would consider normal, although we’d find 63°C a touch torrid so maybe there’s a little too much resolution on the upper end of the scale. Then again, switching to Fahrenheit would shift it toward the hypothermia end of the scale, which isn’t helpful. And you can just forget about Kelvin.

Bug Zapper Counts And Serenades Its Victims

June 11, 2022 by Sven Gregori 10 Comments

Not many creatures are as universally despised as mosquitoes, whether it’s the harmless kind that, at worst, makes you miss winter, or the more serious ones that can be a real threat to your health. A satisfying way to deal with them is to send them off with a bang using one of those racket-shaped high voltage metal mesh bug zappers. [lmu34] saw big potential for some additional gamification here, and decided to equip his zapper with a kill counter and matching sound effects.

The initial thought was that there has to be a way to detect when a mosquito hits the mesh, and use that to trigger further events — in [lmu34]’s case play a sound file and increment a counter. After taking the zapper apart and doing a bit of research, he put theory into practice using a Digispark Pro board containing an ATtiny167, the DFPlayer module for playing a set of WAV files, and an ambitious four digit 7-segment display to keep track of the “score”. A new 3d-printed cover provided enough space to house all the components, including a charging circuit as he swapped the original two AAA batteries with a rechargeable one, which gave a bit more power for the display.

Of course, with these operation voltages, it would be difficult to detect activity on the high voltage side more than once, so [lmu34] went with current sensing instead. He distinguishes between two different levels here and maps them as normal kill and monster kill for the big zaps respectively, playing different sounds for each. Have a look at the video after the break for some quick demonstration.

All in all, this is a delightfully absurd modification that almost screams for an ESP32 to enable multiplayer mode as next iteration. But if chasing mosquitoes with low-tech gadgets isn’t for you, there’s always lasers and good old torture, although those can’t be repurposed to do some hardware fault injections during the winter months then.

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Build Your Own High-Temp Oven Thermometer

December 29, 2021 by Tom Nardi 9 Comments

Looking to keep an eye on the temperature inside his wood-fired pizza oven, [Giovanni Bernardo] decided to skip the commercial offerings and build his own high-temperature thermometer using a type-K thermocouple. The end result is a no-nonsense handheld unit with a surprisingly low part count that, at least in theory, can read temperatures as high as 1023.75°C. Though we hope he’ll be pulling the pizza out long before that.

Inside the 3D printed case we find just a handful of components. The 0.91″ OLED display mounted in the front panel is wired to a Digispark ATtiny85 development board, which in turn is connected to a MAX6675 breakout board. This takes the input from the thermocouple probe and converts it into a digital signal that can be read over SPI with an Arduino library from Adafruit. Rather than going through the added complication of adding a rechargeable pack, [Giovanni] is running this thermometer from a standard 9 V battery thanks to the 5 V regulator built into the Digispark.

We especially appreciate the attention to detail [Giovanni] put into his case design. Each component is nestled into a perfectly formed pocket in the bottom of the box, and he’s even gone through the trouble of using heat-set inserts for the front panel screw holes. It would have been quicker and easier to just model up a basic box and hot glue his components in place, but he took the long way around and we respect that.

This project is another example of an interesting principle we’ve observed over the years. Put simply, if somebody is going through this much trouble to check an object’s temperature, there’s a higher than average chance they intend on eating it at some point.

Low-Cost Computer Gesture Control With An I2C Sensor

November 12, 2021 by Tom Nardi 6 Comments

Controlling your computer with a wave of the hand seems like something from science fiction, and for good reason. From Minority Report to Iron Man, we’ve seen plenty of famous actors controlling their high-tech computer systems by wildly gesticulating in the air. Meanwhile, we’re all stuck using keyboards and mice like a bunch of chumps.

But it doesn’t have to be that way. As [Norbert Zare] demonstrates in his latest project, you can actually achieve some fairly impressive gesture control on your computer using a $10 USD PAJ7620U2 sensor. Well not just the sensor, of course. You need some way to convert the output from the I2C-enabled sensor into something your computer will understand, which is where the microcontroller comes in.

Looking through the provided source code, you can see just how easy it is to talk to the PAJ7620U2. With nothing more exotic than a switch case statement, [Norbert] is able to pick up on the gesture flags coming from the sensor. From there, it’s just a matter of using the Arduino Keyboard library to fire off the appropriate keycodes. If you’re looking to recreate this we’d go with a microcontroller that supports native USB, but technically this could be done on pretty much any Arduino. In fact, in this case he’s actually using the ATtiny85-based Digispark.

This actually isn’t the first time we’ve seen somebody use a similar sensor to pull off low-cost gesture control, but so far, none of these projects have really taken off. It seems like it works well enough in the video after the break, but looks can be deceiving. Have any Hackaday readers actually tried to use one of these modules for their day-to-day futuristic computing?

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Tiny pomodoro timer starts as soon as you plug it in.

Cherry Pomodoro Timer Forces You To Follow

October 31, 2021 by Kristina Panos 13 Comments

If you have trouble staying focused and getting work done, the Pomodoro Technique of working in 25-minute intervals with 5-minute breaks is pretty hard to beat. The only problem is that it requires a lot of input from the user, and all that timer-setting can get in the way of actually getting down to business. The absolute worst is when you find yourself working hard, but see that forgot to set the damn timer (ask us how we know). In essence, the tomato itself can only do so much — you have to actually use it and honor the timer, put in the work, and believe in the system.

But what if you didn’t have to do as much? With [Erfan Sn]’s design, all you have to do is plug it in to a USB port and the countdown starts automatically. Not only does this Pomodoro timer force you to get with the program, it also makes you take breaks from the screen by putting the computer into sleep mode when the 25 minutes (or whatever time you set in the software) are up. This thing even keeps track of your Pomodoro count.

At the heart of this build is the Digispark ATtiny85 dev board, which has a handy onboard USB plug. It can be built with or without the OLED screen, which is good if you are easily distracted by the timer itself. This cherry tomato only costs about $10 to make, it’s tiny, and you can take it anywhere.

As you will see in the gifs on GitHub, [Erfan Sn] has it plugged into a female USB-A to male USB-C, which is probably better for the computer long-term, what with all the plugging and unplugging. When we make ours, we’ll probably plug it into a hub that has power switches for each port.

If all of this sounds like too much work, check out this build that senses whether or not you’re in the chair.

Digispark Spoofs IR To Get Speakers Under Control

November 24, 2020 by Tom Nardi 12 Comments

The Microlab 6C are a pretty nice pair of speakers, but [Michał Słomkowski] wasn’t too thrilled with the 8 watts they consume when on standby. The easy fix is to just unplug them when they aren’t in use, but unfortunately the digital controls on the front panel mean he’s got to turn them on, select the correct input, and turn the volume up to the appropriate level every time they’re plugged back in. Surely there must be a better way.

His solution was to use a Digispark to fire off the appropriate IR remote codes so they’d automatically be put back into a usable configuration. But rather than putting an IR LED on one of the GPIO pins, he simply spliced it into the wire leading back from the speaker’s IR receiver. All his code needs to do is generate the appropriate pulses on the line, and the speaker’s electronics think its a signal coming in from the remote.

Distinctive patterns on the IR sensor wires.

Power for the Digispark is pulled from the speaker itself, so it turns on once [Michał] plugs them back in. The code waits five seconds to make sure the hardware has had time to start up, then proceeds with the “Power On”, “Change Input”, and “Volume Up” commands with a few seconds in between each for good measure.

Not only was it easier to skip the IR and inject the signals directly, but it also made for a cleaner installation. Since the microcontroller doesn’t need line of sight to the IR receiver, [Michał] was able to hide it inside the speaker’s enclosure. From the outside, the modification is completely invisible.

We’ve seen similar code injection tricks used before, and it’s definitely one of those techniques you should file away mentally for future reference. Even though more and more modern devices are embracing WiFi and Bluetooth control, the old school IR remote doesn’t seem like it’s going away anytime soon.

Door Mutes Microphone To Prevent Remote Learning Humiliation

November 8, 2020 by Chris Lott 16 Comments

In a kind of reverse twist on the doorbell, [TheStaticTurtle] whipped up a system to mute his computer’s microphone whenever someone opens the door to his room. He lives in France, where the government announced a strict lockdown last Friday. Like many university students around the world these days, he is now forced to take online classes. Even though he has his own room, occasionally someone will barge in and announce something, often to [TheStaticTurtle]’s embarrassment. When his classmates suddenly heard “Do you want some pie?” the other day, it was the last straw.

His first decision was to sense the door opening with a magnet and sensor, which he stuck to the door and frame with hot glue. He then ran a long cable to his desk, where it connected to an ATTiny 85 with a DigiSpark boot-loader. He wrote firmware to simulate special key combinations, which were then registered with his audio routing software Voicemeeter Potato. We presume he isn’t using an external mic, in which case muting might have been easier to accomplish with a hardware switch. All in all, this is a pretty clever and timely hack. Should you be in a similar predicament and want to try this out, he’s published the source code on GitHub.

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