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.
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.
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?
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.
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.
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.
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.
To be clear, of course there’s a blade. They aren’t magic, obviously. The fan is just small, and hidden inside the base. Air is pulled from the sides and bottom, and into the ring mounted to the top of the unit. When the air eventually exits the thin slit in the ring, it “sticks” to the sides due to the Coandă effect and produces a low pressure zone in the center. That’s all a fancy way of saying that the air flow you get from one of these gadgets is several times greater than what the little dinky fan would be capable of under normal circumstances. That’s the theory, anyway.
We can’t promise that all the physics are working as they should in this 3D printed version, but in the video after the break it certainly appears to be moving a considerable amount of air. It’s also quite loud, but that’s to be expected given it’s using a brushless hobby motor. To get it spinning, [Elite Worm] is using a Digispark ATtiny85 connected to a standard RC electronic speed control (ESC). The MCU reads a potentiometer mounted to the side of the fan and converts that to a PWM signal required by the ESC.
Beyond the electronics, essentially every piece of this project has been printed on a standard desktop 3D printer. An impressive accomplishment, though we probably would have gone with a commercially available propeller for safety’s sake. On the other hand, the base of the fan should nicely contain the shrapnel created should it explode at several thousand RPM. Probably.