While they’re probably rare as hen’s teeth in the US, there have been a few major stores around the world that have started rolling out electronic shelf labels for every item in the store. These labels ensure every item on a shelf has the same price as what’s in the store’s computer, and they’re all controlled by an infrared transceiver hanging on the store’s ceiling. After studying one of these base stations, [furrtek] realized they’re wide open if you have the right equipment. The right equipment, it turns out, is a Game Boy Color.
The shelf labels in question are controlled by a base station with a decidedly non-standard carrier frequency and a proprietary protocol. IR driver chips found in phones are too slow to communicate with these labels, and old PDAs like Palm Pilots, Zauruses, and Pocket PCs only have an IrDA chip. There is one device that has an active development scene and an IR LED connected directly to a CPU pin, though, so [furrtek] started tinkering around with the hardware.
The Game Boy needed to be overclocked to get the right carrier frequency of 1.25 MHz. With a proof of concept already developed on a FPGA board, [furrtek] started coding for the Game Boy, developing an interface that allows him to change the ‘pages’ of these electronic labels, or display customized data on a particular label.
There’s also a much, much more facepalming implication of this build: these electronic labels’ firmware is able to be updated through IR. All [furrtek] needs is the development tools for the uC inside one of these labels.
There’s a great video [furrtek] put together going over this one. Check that out below.
Continue reading “Game Boy vs. Electronic Shelf Labels”
The Raspberry Pi board camera has a twin brother known as the NoIR camera, a camera without an infrared blocking filter that allows anyone to take some shots of scenes illuminated with ‘invisible’ IR light, investigate the health of plants, and some other cool stuff. The sensor in this camera isn’t just sensitive to IR light – it goes the other way as well, allowing some investigations into the UV spectrum, and showing us what bees and other insects see.
The only problem with examining the UV spectrum with a small camera is that relatively, the camera is much more sensitive to visible and IR than it is to UV. To peer into this strange world, [Oliver] needed a UV pass filter, a filter that only allows UV light through.
By placing the filter between the still life and the camera, [Oliver] was able to shine a deep UV light source and capture the image of a flower in UV. The image above and to the right isn’t what the camera picked up, though – bees cannot see red, so the green channel was shifted to the red, the blue channel to the green, and the UV image was placed where the blue channel once was.
Continue reading “Using the Raspberry Pi To See Like A Bee”
[Noe] over at Adafruit has a really great build that combines the Internet’s love of blinkey LEDs and rayguns with the awesome technology behind extraordinarily expensive thermal imaging cameras. It’s a light painting infrared heat gun, used for taking long exposure photographs and ‘painting’ a scene red or blue, depending on the temperature of an object.
While this isn’t a proper FLIR camera, with a DSLR and a wide open shutter, it is possible to take pseudo-thermal images by simply ‘painting’ a scene with the light gun. This is an absurdly clever technique we’ve seen before and has the potential to be a useful tool if you’re looking for leaks around your windows, or just want to have a useful cosplay prop.
The circuit inside this raygun is based on a contactless infrared sensor connected to an Adafruit Gemma, with the LEDs provided by a NeoPixel ring. There are two 3D printable cases – your traditional raygun/blaster, and a more pragmatic wand enclosure. With either enclosure, it’s possible to take some pretty heat map pictures, as seen in the video below.
Continue reading “A Light Painting Infrared Ray Gun”
[Brian] started out with a clear and concise goal, “allow a regular human to associate an audible tone with a temperature from an infrared contactless thermometer.” With his latest project, the ESPeri.IRBud, he has achieved this goal.
One of our favorite parts of [Brian’s] post is his BOM. Being able to easily see that the IR temperature sensor costs $26 at DigiKey is unbelievably helpful to readers. This specific sensor was chosen because others have successfully interfaced it with the Arduino. Not having to reinvent the wheel is good thing! For the build, [Brian] decided to hook up the IR temperature sensor to a re-purposed flexible iPhone headset wire. Having used headphone sockets to connect to the sensor and speakers, the actual device is quite modular. Hearing this thing in action is quite cool, it almost sounds like old-school GameBoy music! Check it out after the break.
Have you used an IR temperature sensor in one of your projects? Let us know.
Continue reading “Modular Arduino Based Infrared Thermometer”
We love writing up projects that re-use lots of old parts. In fact, we save the links and use them as defense when our significant other complains about the “junk” in the basement. No, that tactic hasn’t ever worked, but we’re going to keep trying. Case in point, [Wotboa] needed a non-contact tachometer. There are plenty of commercial products which do just that. After consulting his parts bin, [wotboa] realized he had everything he needed to hack out his own. An IR break beam sensor from an old printer was a perfect fit in an aluminum tube. With the outer shell removed, the emitter and detector were mounted in the nylon shell of an old PC power supply connector, effectively turning them pair into a reflective sensor. To amplify the circuit, [wotboa] used a simple 2n2222 transistor circuit. The key is to keep the voltage seen by the sound card the range of a line level signal. This was accomplished by adding a 2.2 Megohm resistor in line with the output. [wotboa] drew his schematic in eagle, and etched his own PCB for the project. Even the tachometer’s case came from the parts bin. An old wall wart power supply gave up its shell for the cause, though [wotboa] is saving the transformer for another project.
For sensing, [wotba] used [Christian Zeitnitz’s] Soundcard Oscilloscope software. Measuring the RPM of the device under test is simply a matter of determining the frequency of the signal and multiplying by 60. A 400 Hz signal would correspond to a shaft turning at 24,000 RPM. The circuit performs well in the range of RPM [wotboa] needs, but using a sound card does have its limits. The signals on the scope look a bit distorted from the square waves one would expect. This is due to the AC coupled nature of sound cards. As the signal approaches DC, the waveform will become more distorted. One possible fix for this would be to remove the AC coupling capacitor on the sound card’s input. With the capacitor removed, an op amp buffer would be a good idea to prevent damage to the sound card.
[Saulius] couldn’t find a cost-effective wireless scale that did what he wanted, so he reverse engineered the communication protocol for an off the shelf model to get weight data himself.
[Saulius] bought a cheap Maxim 29-66SH scale that uses infra-red to communicate to a detachable digital readout. Using the USB IR toy, [Saulius] intercepted the messages that were broadcast. After a little reverse engineering and with the help of some Python scripts, he soon discovered the protocol his scale was using to encode weight messages.
Since all the communication is through IR, there is no need to do any invasion of the scale as the receiver can be placed anywhere in line of sight from the transmitter on the scale itself.
Check out the demo video for the whole thing in action. If patching into the scale isn’t hard enough, you should just build one from scratch.
Continue reading “Listening to a Smart Scale”
At the end of every semester, we get a bunch of cool and well-documented student projects from Cornell’s ECE4760 class. [Scott] and [Alex]’s infrared theremin is no exception.
The classic theremin design employs each of the player’s hands as the grounded plate of a variable capacitor in an LC circuit. For the pitch antenna, this circuit is part of the oscillator. For the volume antenna, the hand capacitor detunes another oscillator, changing the attenuation in the amplifier.
[Scott] and [Alex] put a twist on the theremin by using two IR sensors to control volume and pitch. The sensors compute the location of each hand and output a voltage inversely proportional to its distance from the hand. An ATMega1284P converts the signal to an 8-bit binary number for processing. They built four voices into it that are accessible through the push-button switch. The different voices are created with wave combinations and modulation effects. In addition to Classic Theremin, you can play in pure sine, sawtooth, and FM modulation.
If you’re just not that into microcontrollers, you could build this digital IR theremin instead. If you find IR theremins soulless or plebeian, try this theremincello.
Continue reading “IR Theremin Speaks In Four Voices”