An infrared (IR) emitting diode is a semiconductor device whose operating spectrum is located in the near-infrared region: from 760 to 1400 nm. The term “IR LED” is often used on the Internet, although it does not emit light visible to the human eye. That is, within the framework of physical optics this term is incorrect, but in a broad sense the name is applicable. It is worth noting that during operation of some IR emitting diodes, a weak red glow can be observed, which is explained by the blurring of the spectral characteristics at the border with the visible range.

IR LEDs should not be confused with infrared laser diodes. The operating principle and technical parameters of these devices are very different.

Application area

Let’s take a closer look at what infrared LEDs are and where they are used. Many of us encounter them every day without knowing it. Of course, we are talking about remote controls. remote control(RC), one of the most important elements of which is the IR emitting diode. Due to its reliability and low cost, the method of transmitting a control signal using infrared radiation has become widespread in everyday life. These remote controls are mainly used to control the operation of televisions, air conditioners, and media players. When you press a button on the remote control, the IR LED emits a modulated (encrypted) signal, which is received and then recognized by a photodiode built into the body of the household appliance. In the security industry, video cameras with infrared illumination are very popular. Video surveillance, supplemented with IR illumination, allows you to organize round-the-clock monitoring of the protected facility, regardless of weather conditions. In this case, IR LEDs can be built into the video camera or installed in its working area in the form of a separate device - an infrared spotlight. The use of high-power IR LEDs in the floodlights allows for reliable control of the surrounding area.

Their scope of application is not limited to this. The use of IR emitting diodes in night vision devices (NVDs), where they perform the function of illumination, has proven to be very effective. With the help of such a device, a person can distinguish objects at a fairly large distance in the dark. Night vision devices are in demand in the military sphere, as well as for covert night surveillance.

Types of IR Emitting Diodes

The range of LEDs operating in the infrared spectrum includes dozens of items. Each individual specimen has certain characteristics. But overall, everything semiconductor diodes The IR range can be divided according to the following criteria:

• radiation power or maximum forward current;
• purpose;
• form factor.

Low-current IR LEDs are designed to operate at currents of no more than 50 mA and are characterized by a radiation power of up to 100 mW. Imported samples are manufactured in an oval 3 and 5 mm housing, which exactly replicates the dimensions of a conventional two-terminal indicator LED. Lens color ranges from transparent (water clear) to translucent blue or yellow. Russian-made IR emitting diodes are still produced in miniature packages: 3L107A, AL118A. High-power devices are produced both in DIP housing and using SMD technology. For example, SFH4715S from Osram in an smd housing.

Specifications

On electrical diagrams IR emitting diodes are designated in the same way as LEDs, with which they have much in common. Let's consider their main specifications.

Operating wavelength– the main parameter of any LED, including infrared. The passport for the device indicates its value in nm, at which the highest radiation amplitude is achieved.

Since an IR LED cannot operate at only one wavelength, it is customary to indicate the width of the emission spectrum, which indicates a deviation from the declared wavelength (frequency). The narrower the radiation range, the more power is concentrated at the operating frequency.

Rated forward current – D.C., at which the declared radiation power is guaranteed. It is also the maximum permissible current.

Maximum pulse current– current that can be passed through the device with a fill factor of no more than 10%. Its value can be ten times higher than direct direct current.

Forward voltage– voltage drop across the device in the open state when the rated current flows. For IR diodes, its value does not exceed 2V and depends on the chemical composition of the crystal. For example, UPR AL118A=1.7V, UPR L-53F3BT=1.2V.

Reverse voltage– the maximum voltage of reverse polarity that can be applied to the p-n junction. There are instances with a reverse voltage of no more than 1V.

IR emitting diodes of the same series can be produced with different scattering angles, which is reflected in their markings. The need for similar devices with a narrow (15°) and wide (70°) radiation flux distribution angle is caused by their different scope of application.

In addition to the basic characteristics, there are a number of additional parameters that should be taken into account when designing circuits for operation in pulsed mode, as well as in environmental conditions other than normal. Before carrying out soldering work, you should familiarize yourself with the manufacturer’s recommendations on observing the temperature regime during soldering. You can find out about the permissible time and temperature intervals from the datasheet for the infrared LED.

Read also

Today in radio electronics there are a wide variety of products used to create high-quality and effective lighting. One such product is an infrared diode type.

To use it to create backlighting, you need to know not only where they are used, but also their features. This article will help you understand this issue.

Features of diodes operating in the infrared range

Infrared LEDs (abbreviated as IR diodes) are semiconductor elements of electronic circuits, which, when current passes through them, emit light in the infrared range.

Note! Infrared radiation is invisible to the human eye. This radiation can only be detected by using stationary video cameras or mobile phone video cameras. This is one way to check whether a diode operates in the infrared spectrum.

High-power LEDs (for example, laser type) in the infrared spectral range are produced on the basis of quantum-sized heterostructures. An FP type laser is used here. As a result, the LED power starts at 10 mV, and the limiting threshold is 1000 mV. Housings for this type of product are suitable for both 3-pin and HHL types. As a result, the radiation appears in the spectrum from 1300 to 1550 nm.

IR Diode Structure

As a result of this structure, a high-power laser diode serves as an excellent source of radiation, due to which it is often used in fiber-optic information transmission systems, as well as in many other areas, which will be discussed below.
The infrared laser diode type is a source of powerful and concentrated laser radiation. In its work, the laser principle of operation is used.
Power diodes (laser type) have the following technical characteristics:

Note! Due to the fact that the product emits light in the infrared range, such familiar characteristics as illumination, power of emitted light flux, etc. don't fit here.

Graphic display of solid angle in 1 sr

• such LEDs are capable of generating waves in the range of 0.74-2000 microns. This range serves as the limit when radiation and light have a conventional division;
• power of generated radiation. This parameter reflects the amount of energy per unit time. This power is additionally tied to the dimensions of the emitter. This parameter is measured in W per unit of available area;
• intensity of the emitted flux within the frame of the volumetric angle segment. This is a rather conditional characteristic. It is due to the fact that, with the help of optical systems, the radiation emitted by the diode is collected and then directed in the required direction. This parameter is measured in watts per steradian (W/sr).

In some situations, when there is no need for a constant flow of energy, but pulsed signals are sufficient, the above-described structure and characteristics make it possible to increase the power of energy emitted by a radio circuit element several times.

Note! Sometimes in the characteristics of infrared diodes, indicators for continuous and pulsed operating modes are distinguished.

How to check functionality

Checking the IR diode

When working with this element of the electrical circuit, you need to know how to check its operation. So, as already mentioned, you can visually check the presence of this radiation using video cameras. Here you can evaluate performance using conventional mobile phone video cameras.
Note! The use of video cameras is the most in a simple way checks.

This IR element in the remote control is easy to check; you just need to point it at the TV and press the button. If the system is working properly, the diode will flash and the TV will turn on.
But you can empirically check the performance of such an LED using special equipment. A tester is suitable for these purposes. To test an LED, the tester should be connected to its terminals and set to the mOm measurement limit. After that, we look at it through the camera, for example through mobile phone. If a beam of light is visible on the screen, then everything is in order. That's the whole test.

Scope of application of IR diodes

At this point in time, infrared LEDs are used in the following areas:

• in medicine. Such elements of radio circuits serve as a high-quality and effective source for creating directional illumination for a variety of medical equipment;
• in security systems;
• in an information transmission system using fiber optic cables. Due to their special structure, these products are capable of working with multimode and single-mode optical fiber;
• research and scientific spheres. Such products are in demand in the processes of pumping solid-state lasers during scientific research, as well as backlighting;
• military industry. Here they have the same wide application as illumination as in the medical field.

In addition, such diodes are found in various equipment:

• devices for remote control of equipment;

IR diode in the remote control

• various control and measuring optical instruments;
• wireless communication lines;
• switching optocoupler devices.

As you can see, the scope of application of this product is impressive. Therefore, you can purchase such diode components for your home laboratory without special problems, they are sold in abundance on the market and in specialized stores.

Conclusion

Today in the effectiveness of infrared powerful LEDs there is no need to doubt. This is confirmed by the fact that such elements of electrical systems have a wide range of applications. Due to their structure, IR LEDs are distinguished by impeccable performance characteristics and high-quality work.

How to make a ceiling wooden chandelier with your own hands
LED color temperature indicator
Why you should pay attention to lamps on rods

remote control (RC)

90% of remote controls are defects of two types:

1) some buttons do not work (usually those that were frequently pressed). In this case, you need to cut out a piece of foil and glue it to the rubber base on the contact side. To do this, use silicone glue;

2) often the defect occurs as a result of the remote control falling. Quartz fails. Any remote control can be tested on a portable receiver that has KB and CB waves. You need to bring the front of the remote control closer to the receiver and press any button. Noise will be heard from the emitter (see below).

Restoring the conductive surface of buttons

You need to take polyethylene from fonts (and the like), the tougher the better. Cut a rectangle according to the format of the printed circuit board. Mark on it the centers of the holes corresponding to the centers of the buttons. Next, drill or punch holes with a diameter equal to the diameter of the contact pad.

It is necessary to make all the holes that are on the printed circuit board. We make a conductive layer. Take baking foil (new, not wrinkled), and stick tape on it. We cut out a rectangle according to the format of the board, make technological holes, as on the board (you need to cut a hole under the LED). We assemble it - put foil on the buttons (adhesive tape on the buttons), and a board on top. Then close the remote control.

The secret to restoring conductivity

graphite layer on remote controls

For this, a graphite emulsion is prepared: “earplugs” are dissolved in any solvent for nitro paints. After this, graphite is gradually added to the solution - the finer the better. For this you can use a regular pencil.

This solution should be used to cover the torn section of the graphite conductor.

Option to check remote controls

For faulty video units and TVs, there are always IR signal receiver units in stock. They are soldered into the screen and usually have 3 pins.

The LED is connected directly to the terminals of the block: “+” - to the “+” power supply, “-” - to the output. Stabilized power supply - 3…9 V.

The quartz in the remote control can also be assessed by the blinking frequency of the LED (they “glitch” quite often).

How to increase the efficiency of remote control

With deterioration (over service life) of the electrical characteristics of batteries (loss of battery capacity and decrease in battery current and voltage) for efficient work the remote control is required to be proportionally closer to the IR signal receiver. This is the first sign of the need to replace batteries.

The operating range of a conventional remote control with one IR emitting diode, which usually does not exceed 5-6 m in open areas (unfocused flow), and in conditions of interior obstacles, 10-12 m can be increased 2 times by installing in series with the standard one, a similar IR diode. In this case, the additional IK diode must be turned on in the forward direction and installed next to the first one. To do this, you will need to carefully disassemble the remote control housing, and depending on the design features of the installation of the basic IR diode (behind a protective glass screen or in an open state with a protruding working surface of the diode outside the remote control housing), drill a hole to accommodate another IR diode.

If a similar IR emitting diode is not available or, as often happens, it is impossible to determine exactly the type of standard IR diode used in the remote control (for remote controls with a circuit supply voltage of up to 6 V), it is allowed to switch on AJI156A, AJI147A, AJI164A9, AL164A91 (foreign analogs of L -315EIR, L-514CIR). They have a transparent bulb color, forward current reaches 100 mA, wavelength 920-940 nm, radiation power 8-10 mW.

Increase supply voltage electronic circuit There is no need for a remote control pulse shaper, just as there is no need for other intervention in the standard circuit. Increasing the range of the remote control has been tested with the Setro STV-2080MH models, the remote control of the MAX-930 minisystem manufactured by Samsung, the remote control of the W131W video player and others.

The easiest way to check the remote control

This method can be used to quickly check the remote control anywhere, even in the field, if necessary.

To do this, you will need a simple radio receiver with a medium wave range, for example, “0lympic-402” or “Selga-401-405”, produced by the domestic industry. Today, there are many such radio receivers that receive radio waves in the medium wave range, and their “Chinese” names make one’s eyes dazzle.

When testing the remote control using the proposed method, it is not the presence of IR radiation that is checked, but radio interference created by the electronic components of the remote control is recorded. It is known that each radio element is, to one degree or another, a source of electromagnetic interference “noise” and weak radiation of radio waves. At a short distance from the radiation source, these “noises” are recorded by a “Selga” radio receiver.

Throughout the entire medium wave range, an intermittent signal will be heard in the radio receiver audio frequency(with a frequency of approximately 400 Hz) if a button is pressed on a nearby (at a distance of up to 1 m) remote control (with batteries inserted). While the button is pressed, the radio emits an audio frequency signal through the speaker. Using the same method, you can control the effectiveness of pressing all the buttons on the remote control, because it is important that they are all pressed with approximately the same force. This method is especially important when the remote control, for example, for a TV in the kitchen, is bought at the market or “from hand”. Everything is possible here.

In order not to buy a “pig in a poke”, it is wise to take with you a portable radio receiver with the ability to receive medium waves and, when checking, insert the batteries into the remote control and check the pressing of each button on the remote control. Each press of a working remote control will certainly be accompanied by a sound signal in the radio receiver (over the entire medium wave broadcast range) from a distance of up to 1 m.

The second life of radios like “Selga-404” and similar ones does not end with this recommendation. This type radio receivers configured to receive medium waves can also effectively control the operation (from a short distance of up to 1-2 m) of IR transmitting devices of various security systems, for example, alarms or the operation of remote transmitting devices (bugs) that transmit information via IR LEDs.

In addition to the Selga radio receiver of various modifications, any (including modern) radio receiver that works reliably in the medium wave range is suitable for checking the remote control and performing related tasks.

You will have to check the serviceability of the IR emitting diode in the remote control using another method (for example, the first one recommended in this article), however, for checking the operation of the remote control electronics, this method has no analogues in its simplicity.

Sometimes, in order to make some switches with the remote control, you need to get up and come almost close to the device being controlled. And sometimes, you have to rotate the remote control and frantically, pressing buttons, try, like a shooter, to get into the infrared radiation receiver of the device.
In such cases, you want to run the remote control to hell and manually switch the desired mode.

Why is this happening?

The fact is that earlier in household appliances used higher quality electronic components. Now they are trying to save on everything by using parts at a lower price. It is the use of a cheap infrared LED with low radiation power and a low-quality lens that leads to the above problems.
What can be done in cases where the remote control does not function at all or works at close range?
Below in the article, a method for repairing and increasing the range of the remote control will be described. It won’t take much time, much less money.

Remote control diagnostics

You can check whether the remote control works or not in a simple way.
To do this, firstly, you need to insert new batteries into it. Secondly, turn on the phone camera and point the remote control at it and press the “ON” button. You should see the infrared diode light up on the phone screen.

The human eye does not see this radiation spectrum, but the phone’s camera records it, and on the display this glow is similar to the indication of a regular LED.
If this does not happen, then the remote control is faulty.
In such cases, replacing the infrared diode may help.
The method for repairing and upgrading the remote control is similar, so the modernization will be described below.

The prefix is ​​taken as an example digital television T2, controlled by remote control.
The console itself has no complaints about its operation, but the control panel leaves much to be desired. Even with new batteries, a person who wants to make some switches must approach the device at a distance of less than two meters, which is not entirely convenient. If you are further than this distance, the remote control becomes simply invisible and impossible to control.

Modernization - repair

The modernization itself consists of replacing the infrared LED with another, more powerful one.
You can take such an LED from the remote control of an old VCR, faulty DVD player, air conditioner or music center.

If you don’t have one at home, then a similar remote control can be purchased at flea markets for pennies. The main thing is that it is working and is powered by two batteries with a total voltage of three volts.
When going to the market, you need to take two AA batteries to check the remote control, and a mobile phone, which, in principle, should always be nearby.
Having found a suitable remote control, insert the batteries into it and turn on the phone camera. Point the remote control LED at it and press any button. A working remote control should emit infrared light, which will be visible on the phone screen, in the form of a burst of pulses.

If this is not visible, then the remote control is most likely faulty, and there is no point in buying one.
In the photo, the remote control is unknown, either from the air conditioner or from the heater, but it is definitely working, and with a powerful infrared diode. The air conditioner itself has been gone for a long time; it was broken and could not be repaired. He will be the donor.

Usually the two halves of the remote control body are held together with a latch, but there are times when there is also a fastening screw that is located under the batteries in the battery compartment. If there is one, then unscrew it, and then, using a knife to pick out the junction of the two parts, we separate them.

When the case is disassembled, inside it we find a control board on which there are electronic components, a button pad and the infrared LED itself.

Next, we put the old remote control aside and disassemble the one we want to upgrade. In our case, this is the remote control for the T2 set-top box.
The principle of disassembly is the same as in the first case. We unscrew the fastening screw - if there is one, and use a knife or screwdriver to separate the halves of the case.

In the photo, a board with an infrared diode.

Next, take a 25 or 40 W soldering iron and solder the diode from the donor board.
It is very important not to overheat the device with a soldering iron, because semiconductor devices need to be soldered for no more than two seconds, otherwise they may be destroyed. Also, you need to be careful with the legs of the diode so as not to bend them again and not break them.

Before soldering the diode, you need to determine the polarity - where is the anode and where is the cathode, or the positive and negative terminals.

It happens that the polarity is indicated on the board, but most often there is no marking, so you should immediately determine where the positive terminal is and mark it on the board.

You can determine the output in a simple way. You need to carefully look at the diode with a magnifying glass, and the terminal in the housing that is shorter is the anode (plus), and the one that is larger and wider is the cathode or minus.

Having determined on the board of the T2 remote control where the positive terminal is, we make a mark by scratching it with something sharp, for example an awl.
Now you can desolder the diode from the board.

Since the soldered donor diode has shorter legs than the one that should be replaced, there is no need to solder the diode from the T2 board. It must be bitten off with pliers, leaving small conclusions. We will solder the donor diode to them. Thus, the length must be sufficient for the diode lens to extend beyond the closed housing.
We tin the leads on the diode and the ends on the board, and carefully - observing the polarity - solder them to each other.

We check the strength of the soldering by tugging on the diode.

We insert the board into the lower part of the case and snap it into place at the top.

At the end of the USSR, domestic semiconductor televisions of the USCT series appeared and were very popular. Some of them are still in service. TVs with a screen size of 51 cm diagonally were especially durable (the kinescope was very reliable). Of course, they no longer meet modern requirements at all, but as a “dacha option” they are still quite suitable.

How to make a simple IR remote control for TV

Somehow, out of nothing to do, a desire arose to improve the old, already “dacha” “Raduga-51ТЦ315”, adding a remote control system to it. Now it is impossible to purchase a “native” module, so it was decided to make a simplified single-command system that allows at least switching programs “in a ring”. Microcontrollers and special microcircuits were immediately rejected due to unprofitability, and the system was made from what was available.

Namely, integrated timer 555, IR LED LD271, integrated photodetector TSOP4838, counter K561IE9 and plus more little things. The diagram of the IR control panel is shown on the website. It is a pulse generator with a frequency of 38 kHz, at the output of which an infrared LED is switched on. The generator is built on the basis of the “555” microcircuit, the so-called “integrated timer”. The generation frequency depends on the C1-R1 circuit; when setting up, by selecting resistor R1, you need to set the frequency at the output of the microcircuit (pin 3) to 38 kHz.

Rectangular pulses with a frequency of 38 kHz are supplied to the base of transistor VT1 through resistor R2. Diodes VD1 and VD2 together with resistor R3 form a current control circuit through the IR LED HL1. With increased current, the voltage on R3 increases, and the voltage on the emitter VT1 increases accordingly. And when the voltage at the emitter approaches the drop voltage across the diodes VD1 and VD2, the voltage at the base of VT1 decreases relative to the emitter, and the transistor closes.

Scheme of the receiving unit using IR radiation

Pulses of IR light, following with a frequency of 38 kHz, are emitted by the HL1 infrared LED. Control by one button S1, which supplies power to the remote control circuit. While the button is pressed by the remote control, infrared pulses are emitted. The circuit diagram of the receiving unit is shown in Figure 2. It is installed inside the TV, it is supplied with + 12V power from the TV’s power supply, and the cathodes of the VD2-VD9 diodes are connected to the contacts of the buttons of the USU-1-10 program selection module. IR pulses emitted by the remote control are received by an integrated photodetector HF1 type TSOP4838.

This photodetector is widely used in remote control systems for various household electronic equipment. When a signal is received, there is a logical zero at its pin 1, and a logical one when there is no received signal. Thus, when the remote control button is pressed, its output is zero, and when not pressed, its output is one. TSOP4838 should be powered with a voltage of 4.5-5.5V. and no more. But, to control the TV program selection module, you need to apply 12V voltage to the buttons of the transistor 8-phase trigger. Therefore, a voltage of 12V is supplied to the D1 chip, and a voltage of 4.7-5V is supplied to the photodetector HF1 through a parametric stabilizer on the zener diode VD10 and resistor R4.

Transistor VT1 serves as a cascade matching the levels of logical units. In doing so, it inverts the logic levels. The voltage from the collector VT1 through the circuit R3-C2 is supplied to the counting input of the counter D1, designed to receive positive pulses. The R3-C2 circuit is used to suppress errors from bouncing contacts of the S1 button on the control panel. Counter D1 K561IE9 is a three-digit binary counter, with a decimal decoder circuit at the output.

It can be in one of eight states from 0 to 7, while a logical one is present at only one output corresponding to its state. The remaining outputs are zeros. Each time you press or release the remote control button, the counter moves one state up, and the logical one of its outputs switches. If the countdown started from zero, then after eight presses of the button, on the ninth, the counter will return to the zero position. And then, the process of switching the logical unit along its outputs will be repeated. The LD271 IR LED can be replaced with any IR LED. applicable for remote controls for household appliances. The TSOP4838 photodetector can be replaced with any complete or functional analogue.

The K561IE9 chip can be replaced with a K176IE9 or a foreign analogue. You can use the K561IE8 (K176IE8) chip, and there will be 10 control outputs. To limit them to 8, you need to connect output number “8” to input “R” (in this case, input “R” should not be connected to a common negative, as is shown in the diagram). 1N4148 diodes can be replaced with any analogues, for example. KD521, KD522. The remote control is powered by Krona. Placed in a toothbrush case. Installation - volumetric on the terminals of the A1 chip.

The receiver circuit is also assembled using three-dimensional installation and glued with BF-4 glue to the wooden body of the TV from the inside. For the eye of the photodetector, I used the hole for the connector for connecting headphones (the hole in the TV was empty, closed with a plug, there was no connector). By selecting R1 (Fig. 1), you need to adjust the remote control to the frequency of the photodetector. This can be seen from the longest reception range. If you are interested in the circuit, but there is no old “Rainbow”, it can also be used to switch something more modern. Transistor switches, with electromagnetic relays on collectors or LEDs of powerful optocouplers can be connected to the outputs of the D1 microcircuit through resistors.