How Much Is That Shirt In The (Atmospheric) Window?

October 26, 2021 by Kristina Panos 41 Comments

Summer is fading into a memory now, but as surely as the earth orbits the sun, those hot and sweaty days will return soon enough. And what can you do about it at the level of a single, suffering human being? After all, a person can only remove so much clothing to help cool off. Until someone figures out a way to make those stillsuits from Dune, we need an interim solution in which to drape ourselves.

We’ve seen the whitest paint possible for cooling buildings, and then we saw a newer, whiter and more award-winning paint a few months later. This paint works by the principle of passive cooling. Because of its color and composition, it reflects most light and absorbs some heat, which gets radiated away into the mid-infrared spectrum. It does this by slipping out Earth’s atmospheric window and into space. Now, a team based in China have applied the passive cooling principle to fabric. Continue reading “How Much Is That Shirt In The (Atmospheric) Window?” →

World’s Cheapest And Possibly Worst IR Camera

October 7, 2021 by Al Williams 16 Comments

Don’t blame us for the title. [CCrome] admits it may well be the cheapest and worst IR camera available. The concept is surprisingly simple. Mount a cheap Harbor Freight non-contact thermometer on a 3D printer carriage and use it to scan the target. The design files are available on GitHub.

There is, of course, an Arduino to grab the data and send it to the PC. Some Python code takes care of converting it into an image.

Perhaps you don’t need a camera, but having a way to communicate with an $11 IR temperature sensor might come in handy someday. You do have to mash the measurement button down, so [CCrome] used the 3D printer to make a clamp for the button that also holds the POGO pins to the PCB. We would have been tempted to solder across the switch and also solder the wires to the pad. But, then again, you need a 3D printer for the project anyway.

Don’t expect the results you would get from a real thermal sensor. If you want that, you may have to build it yourself or open your wallet wide. If you need some inspiration for a use case, look at the thermal camera contest from a few years back.

Is Your Movie Too Loud? Can’t Hear The Dialogue? This Circuit Can Help.

September 29, 2021 by Jim Heaney 67 Comments

Everyone loves watching movies, that is, so long as you can hear what the characters on screen are saying. [GreatScott] found this second part difficult while watching through BladeRunner 2049, so he designed an automatic volume adjuster to assist.

At a high level, the solution is fairly straightforward; when there is loud music playing in a movie, turn the volume down. The challenge is how to actually achieve that. The first step was controlling the volume. To avoid having to modify or damage his sound system, [GreatScott] opted instead to mimic the volume up and down signals of his remote over IR. Using the very handy IRremote library for Arduino and its built-in decoding functionality, he was able to identify and replicate the signals with his own IR LED.

The second step in this process was measuring the volume of the movie. [GreatScott] achieved this with a microphone and amplifier circuit, that was then piped into one of the analog pins of the Arduino Pro Micro at the heart of the build. Since the audio being sampled could have a frequency as high as 20 kHz, the ADC Prescaler had to be adjusted from its standard value, which would have only permitted measurements at less than 5 kHz.

The third step was writing the algorithm to detect loud music and adjust the volume accordingly. The Arduino will measure the audio until a sound greater than the dead band value, set with one of the two onboard potentiometers, is detected. This then triggers the Arduino to start a timer, to see how frequently the upper limit is being surpassed. If it is just one or two occasionally loud noises (like a scream, a clap, whistling, etc.) the Arduino will not take any action, but multiple loud noises in rapid succession will then trigger the volume down command over the IR LED. A second potentiometer allows for adjustment of this timer’s critical value, so that you can make the system respond faster or slower depending on the movie.

Once the sound has been detected to have dropped down below a critical vaue, the Arduino assumes that the movie is back to dialog and will increase the volume by the number of times it decreased it before, leaving you back at the perfect volume.

Maybe you’re the type that cares more for the visuals of a movie, rather than the audio. In that case, this e-paper movie display will be perfect for giving you time to appreciate every frame!

Continue reading “Is Your Movie Too Loud? Can’t Hear The Dialogue? This Circuit Can Help.” →

An OSHW IR Remote Control Powered By The ATtiny13A

July 2, 2021 by Tom Nardi 15 Comments

The new hotness in consumer electronics might be RF remotes based on protocols like Bluetooth Low Energy, but there’s still plenty of life left in the classic infrared remote. Especially with projects like TinyRemoteXL from [Stefan Wagner], which let you build and program an IR “clicker” of your own. Whether you want to spin up your own custom universal remote or create a beefed up version of the TV-B-Gone, this open source effort is a great place to start.

As you might have guessed from the name, this project is actually a larger version of the TinyRemote that [Stefan] put together previously. The documentation for that project goes a bit more into the nuts and bolts of talking IR, and is definitely worth a read if you’re into the low level stuff. For the original five button TinyRemote, the hardware consists of little more than a ATtiny13A microcontroller, a pair of IR LEDs, and the transistors to drive them.

But on the XL, things are a bit trickier as there are now twelve buttons for the ATtiny13A to read. Obviously there aren’t enough pins to read so many buttons directly, but with a combination of BAS16TW diode arrays and resistors, [Stefan] is able to detect what button was pressed using the chip’s interrupt pin and ADC. Certainly a handy trick to have in the back of your mind, and the open source nature of this project gives you a great chance to see how it’s implemented.

Between this project and the impressive development board [Djordje Mandic] released recently, it seems we’re looking at something of an infrared hacking revival. Earlier this year we even saw the commercial release of an IR-equipped ESP8266 board.

Arduino Compatible IR Blaster Keeps TVs At Bay

June 8, 2021 by Tom Nardi 39 Comments

The TV-B-Gone is a well known piece of kit in hacker circles: just point it at a noisy TV in a public space, hit the button, and one of the hundreds of IR remote codes for “Power Off” that it blinks out in rapid succession is more than likely to get the intended response. Unfortunately, while a neat conversation starter, its practical use is limited to a single function. But not so with this programmable IR development board that creator [Djordje Mandic] describes as a “TV-B-Gone on steroids”.

Sure you can point it at a random TV and turn it off with a single button press, but you can also plug the board into your computer and control it directly through the serial connection provided by its CP2104 chip. Using a simple plain-text control protocol, the user can modify the behavior of the device and monitor its status. [Djordje] imagines this feature being used in conjunction with a smartphone application for covert applications. To that end, the device’s support for an onboard battery should keep it from draining the phone during extended operations.

Of course you could do something else entirely with it simply by firing up the Arduino IDE and writing some new code for the device’s ATmega328P microcontroller. As with the IR-enabled ESP8266 development board we looked at a few months ago, there are plenty of applications for an all-in-one board that allows you to communicate with the wide world of IR devices.

Continue reading “Arduino Compatible IR Blaster Keeps TVs At Bay” →

The False Alarm That Nearly Sparked Nuclear War

April 16, 2021 by Lewin Day 54 Comments

The date was September 26, 1983. A lieutenant colonel in the Soviet Air Defence Forces sat at his command station in Serpukhov-15 as sirens blared, indicating nuclear missiles had been launched from the United States. As you may have surmised by the fact you’re reading this in 2021, no missiles were fired by either side in the Cold War that day. Credit for this goes to Stanislav Petrov, who made the judgement call that the reports were a false alarm, preventing an all-out nuclear war between the two world powers. Today, we’ll look at what caused the false alarm, and why Petrov was able to correctly surmise that what he was seeing was an illusion.

Continue reading “The False Alarm That Nearly Sparked Nuclear War” →

Adding Remote Control To An Old Stereo

January 29, 2021 by Lewin Day 17 Comments

Sometimes, the best hifi gear is the gear you’ve already got. This is particularly the case in the cassette world, as high quality decks are long out of production. [Nick] liked his current rig, but wanted to be able to use it with a remote from across the room. Naturally, he set to hacking the feature in.

The cassette deck in question, a Yamaha K-220, was old enough to lack a remote, but thankfully new enough to use a computer-controlled tape transport. This meant that the basic features of play, stop, rewind and fast forward can all be controlled with simple digital buttons rather than mechanical ones. This made it easy to interface an ATmega328P to the stereo’s original circuitry. Digital IO pins are hooked up to the buttons, held as high-impedance inputs most of the time, only toggling to ground when necessary to trigger a button press. It was then a simple job to hook up an IR receiver to the chip and program it with some Arduino libraries to work with a typical stereo remote control [Nick] had laying around.

It’s a tidy build, and with more cool cassette releases coming out every year, we’re sure [Nick]’s going to put some miles on the setup. If you find IR too cumbersome though, you can go a step further and replace it with a web app instead. If you’ve been tinkering with similar things in your own workshop, be sure to drop us a line!