Infrared headphones can be used for listening to music or television cordlessly. The headphones utilize a transmitter that connects with audio cables to the audio source, such as a home entertainment center. The transmitter utilizes light-emitting diodes (LEDs) to direct a focused beam of invisible pulsating light towards a receiver built into the headphone set. The pulsations act as ON/OFF signals that are translated digitally by the receiver into audible sound waves. Most infrared headphones have an effective range of about 30 feet (~10 meters) or less, and require a clear line of sight between transmitter and receiver.
The headphones pick up the light with a receiver and turn it back into sound. The receiver has an infrared CDS cell, which produces a pulse of electricity every time infrared light lands on it. The cell is designed to pick up the particular frequency of light produced by the transmitter, so it is not disturbed or thrown off by other light. A small computer inside of the receiver takes these pulses of electricity and turns them into an audio signal. This audio signal is then amplified and sent to the headphones themselves, which play the sound.
For the receiver side, a photodiode D1 feeds high gain IR remote control preamp IC, a CA3237E. U2 is a PLL FM detector tuned to around 100 kHz. The detector output is amplified by U3 and it can drive a speaker or a set of headphones.
Wireless IR Headphone Receiver - [Link]
The most legendary PIN-diode which is also used as a nuclear radiation detector is the BPW34. It is available from several semiconductor manufacturers in different variants and was originally designed for visible and invisible wavelength up to the IR wavelength region. Since such a diode is sensitive to light the use as a nuclear radiation detector requires proper shielded against light. The cost of a BW34 diode is generally below 1 Euro.
Do-it-yourself PIN-diode counter - [Link]
by Jordan Dimitrov @ edn.com:
While most carbon dioxide sensors use IR technology, electrochemical sensors are a serious competitor because of their high sensitivity, wide measurement range, and low price. As a rule, electrochemical sensors connect to a microcontroller through a buffer amplifier with an extremely low bias current (<1pA). The micro is needed to linearize the logarithmic response of the sensor. A good example of this approach is the SEN-000007 module from Sandbox Electronics, which uses an MG-811 CO2 sensor from Hanwei Electronics. Reference 1 reveals the circuits and the code, but does not specify accuracy.
Antilog converter linearizes carbon dioxide sensor - [Link]
by Martin Jagelka , Martin Daricek & Martin Donoval :
Continuous monitoring of heart activity permits measurement of heart rate variability (HRV), a basic parameter of heart health and other diseases.
This Design Idea is a new design of pulse oximetry that excels in its simplicity and functionality. Due to its capabilities, it can be used as a standalone device, able to monitor heart rate and oxygen saturation.
The core of the system is composed of the ultra-bright red LED (KA-3528SURC), infrared LED (VSMB3940X01-GS08), and a photodiode (VBP104SR) sensitive to both wavelengths of light at the same level.
Simple pulse oximetry for wearable monitor - [Link]
by Jose Daniel Herrera:
Here I present another project based on a addressable LEDs strip, based on WS2812b leds.
It consists of an ‘electronic’ candle, which lets you select set colors, adjust the intensity, and have different effects like rainbow, fade and fire. The project arose from the purchase of an IKEA lantern model BORBY … the idea was to replace a candle of considerable size, for something more … modern.
Candle with remote control and Arduino Pro Mini - [Link]
by Vadim Panov:
Back when I was only starting to dabble in electronics, I needed a project that would meet the following requirements:
simple to make;
original (i.e. done entirely by myself from scratch);
containing a microcontroller;
and maybe the most important of all, useful. I’ve had enough devices I assembled just to dismantle the whole thing a month later.
The thing I came up with at the time was a light swich for my room controlled over an IR remote from TV. Remote that I had used RC-5 protocol, hence the firmware is suited for any RC-5 compatible remote.
Everyone is familiar to the everliving problem with switching the lights off in your room before going to bed and stumbling back across the room. The IR switch I describe here solves that problem, and I can definitely tell that this project was a success – I am still using it with no regret.
Infrared remote controlled light switch with ATTiny2313 - [Link]
Infrared remote control for home appliances is a popular project among hobbyists and students. Smart Outlet is a similar project that provides an infrared controlled AC outlet to connect any electric appliance and has an integrated timer in it. The appliance can be turned on and off from several feet away using an IR remote. The device is Arduino-controlled and has a LCD display to provide a menu based interface to the user for its operation and settings.
Infra-red controlled smart AC outlet - [Link]
Here’s a proximity-sensing LEDs project by Will_W_76. He writes a complete step-by-step instructions:
So how does this all work? What makes it proximity-sensing? Remember in the explanation above that the photo-transistor acts like a switch. So when the photo-transistor is off, no current is flowing across it to our blue LED and the LED is off as well. Now look at the other side of our circuit. That’s where the IR LED is connected, and it is connected such that it is always on and emitting 880nm infrared waves. Remember that I also mentioned the photo-transistor is set to respond best to wavelengths of 880nm? That’s how the proximity-sensing works! When an object (such as your hand) goes over this little “cluster”, IR light of 880nm is emitted from the IR LED. This light reflects off of your hand and back to the circuit. When the photo-transistor picks it up, it turns on allowing current to flow through from the source to our blue LED lighting it up!
Proximity sensing LEDs - [Link]
Discovering of overheating and joints with a high resistance has never been easier and safer. With the type Flir i3 now moreover price-affordable.
Thermal cameras, i.e. cameras sensitive in infrared range bring a useful information – picture with virtual colors responding to a temperature of a scanned surface. Maybe, at the word “thermal camera” you too get an idea about a well known usage in buildings – inspection of a heat leakage (thermal bridges) = status of a thermal insulation of buildings. But that´s only one of many ways to use these devices. In electronics and power engineering it´s far more interesting for example:
- searching for faults on a PCB, optimizing of layout in respect to an even heat distribution
- inspection of distribution boxes with cables, terminal blocks and circuit breakers
- inspection of motors and transformers
- inspection of cables interconnections (overheating caused by a high resistance)
- inspection of cooling efficiency – heatsinks, fans, …
- inspection of solar panels
…and all this at full operation and under (often high) voltage.
„I have an infrared thermometer, thus I need no camera” – this is a frequent opinion – until the time, you once try working with a camera. The joke is, that one picture from for example camera Flir i3 with resolution of “only” 60×60 pixels equals to 3600 measurements of an IR thermometer. It can be said, that one picture taken by the camera even exceeds 3600 measurements (done by an IR thermometer), because a spatial resolution of the thermal camera is usually better (surface measured by one pixel is smaller) than that of IR thermometers. This way it can happen, that a small source of heat (for example a small overheated component) can´t be discovered by an IR thermometer, while with a camera it will be clearly visible. Naturally, there are many applications where only an IR thermometer is sufficient, but cameras are far better for a professional usage and a maximum work efficiency.
That´s why we decided to incorporate into our offer the world renowned cameras from company FLIR, which is on the edge of development in this segment. As a standard stock item can be found type Flir i3 (3600 px) with resolution of 0.15°C and a viewing angle 12,5°x 12,5°. Big 2,8“ TFT display shows all necessary information and settings. Very advantageous is a possibility to store up to 5000 snapshots into a uSD card (2GB, jpg) and a consequent transfer of files into a PC through a USB. Further detailed information will provide you the Flir i3 datasheet.
Upon order we´re able to supply you any other type from company FLIR in a short leadtime..
Even hidden faults can be found with FLIR thermal cameras - [Link]
OK, this isn’t very innovative, but it’s still a fun weekend project. The setup starts with a transfer pipette, with a tiny hole made on top so that any water inside will slowly drip. This is followed by a jury-rigged optointerrupter: a fairly standard IR diode, a matched phototransistor, two 5 mm nylon spacers, top half of a polypropylene beaker, and copious amounts of hot-melt glue. The diode is connected to +5V through a 220 Ω resistor; the phototransistor uses a 10 kΩ one, in the usual topology. That’s good enough to detect the light that gets refracted by a passing drop of water.
Catching Drops of Water - [Link]