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How to simply check the performance of infrared diodes. IR LEDs: scope, types and main technical characteristics Diode on the control panel

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! Using video cameras is the easiest way to check.

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 a camera, for example through a 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 illumination;
  • 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 any problems; they are sold in abundance on the market and in specialized stores.

Conclusion

Today there is no doubt about the effectiveness of high-power infrared LEDs. 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.

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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 itself. 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 the deterioration (over service life) of the electrical characteristics of the batteries (loss of battery capacity and decrease in battery current and voltage), effective operation requires a proportionally closer proximity of the remote control 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.

There is no need to increase the supply voltage of the electronic circuit of the 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 audio frequency signal (with a frequency of approximately 400 Hz) will be heard in the radio receiver if any button is pressed on a nearby (at a distance of up to 1 m) button. 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 of radio receiver, 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.

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 (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 in general, all IR semiconductor diodes 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

In electrical diagrams, IR emitting diodes are designated in the same way as LEDs, with which they have much in common. Let's look at their main technical characteristics.

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– direct current, 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

The remote control for consumer electronic equipment is usually a small, battery-powered device with buttons that sends commands via infrared radiation with a wavelength of 0.75-1.4 microns. This spectrum is invisible to the human eye, but is recognized by the receiver of the receiving device. Most remote controls use one specialized command-former chip with a quartz resonator, packaged or unpackaged (placed directly on the printed circuit board and filled with compound to prevent damage), a signal amplifier consisting of one or two transistors, and an IR emitting diode (or two) range. Additionally, some remote controls also install an LED to indicate the sending of commands.

Scheme of the EUR51971 remote control for TV.

IP-Q remote control diagram 1 on the Chip SAA /7 with its own command protocol (number 448), developed byThomson with the assistance of Philips, these TVs can be classified as Saba T6301/FF345. TS342/365/440/460, Telefunken Chassis 418A, FB-180, Thomson Chassis ICC7.


All over the world, the RC-5 remote control system is the most widely used for household radio equipment. This system was developed by Philips for the needs of controlling household equipment and is used in many televisions. A specialized transmitter chip is available for remote controls SAA3010 ( Integral software produces an analogue INA3010 ). The use of a specialized transmitter chip dramatically reduces the required number of components and allows the IR transmitter to be placed in a small package. In addition, such microcircuits solve the issue of low consumption in standby mode, which makes operating the remote control very convenient: there is no need for a separate power switch. The circuit goes into active mode when any button is pressed and returns tomicroconsumptionwhen releasing it. Currently, different manufacturers produce a large number of modifications of RC-5 remote controls, and some models have quite a decent design. Industrial remote controls are usually designed to control televisions. Therefore they use RC-5 code system 0. It’s not at all difficult to switch to a different system number, and then the mutual influence of different remote controls will be eliminated.

When we press the remote control button, the transmitter chip is activated and generates a sequence of pulses that have a filling frequency of 36 KHz. LEDs convert these signals into infrared radiation. The emitted signal is received by a photodiode, which again converts the IR radiation into electrical impulses. These pulses are amplified and demodulated by the receiver chip. They are then fed to the decoder. Decoding is usually done in software using a microcontroller. The RC5 code supports 2048 commands. These teams make up 32 groups (systems) of 64 teams each. Each system is used to control a specific device such as a TV, VCR, etc. One of the most common transmitter chips is the SAA3010 chip. The SAA3010 transmitter chip allows power supply voltage +5V.

· Supply voltage – 2...7V

· Current consumption in standby mode – no more than 10 µA

· Maximum output current - ±10 mA

· Maximum clock frequency – 450 KHz

The block diagram of the SAA3010 chip is shown in Figure 1.

Figure 1. SAA3010 IC structure.

The description of the pins of the SAA3010 chip is given in the table:

Designation

Button matrix input lines

Operating mode selection input

Button matrix input lines

Modulated output data

Output

Scan outputs

Scan outputs

Generator input

Test input 2

Test input 1

Button matrix input lines

Supply voltage

The transmitter chip is the basis of the remote control. In practice, the same remote control can be used to control several devices. The chip can address 32 systems in two different modes: combined and single system mode. In combined mode, the system is selected first, and then the command. The number of the selected system (address code) is stored in a special register and a command related to this system is transmitted. Thus, to transmit any command, successive pressing of two buttons is required. This is not entirely convenient and is only justified when working simultaneously with a large number of systems. In practice, the transmitter is more often used in single system mode. In this case, instead of the matrix of system selection buttons, a jumper is mounted, which determines the system number. In this mode, transmitting any command requires pressing only one button. By using the switch, you can work with multiple systems. And in this case, only one button press is required to transmit the command. The command transmitted will be related to the system currently selected using the switch.

To enable the combined mode, a low level must be applied to the SSM (Single System Mode) transmitter output. In this mode, the transmitter IC operates as follows: During rest, the X and Z lines of the transmitter are driven high by internal p-channel pull-up transistors. When a button in the X-DR or Z-DR matrix is ​​pressed, the keyboard debounce cycle is initiated. If the button is closed for 18 clock cycles, the “generator enable” signal is fixed. At the end of the debouncing cycle, the DR outputs are turned off and two scan cycles are started, turning on each DR output in turn. The first scan cycle detects the Z address, the second scan detects the X address. When the Z-input (system matrix) or X-input (command matrix) is detected in the zero state, the address is latched. When you press a button in the system matrix, the last command (i.e., all command bits are equal to one) in the selected system is transmitted. This command is transmitted until the system select button is released. When a button is pressed in the command matrix, the command is transmitted along with the system address stored in the latch register. If the button is released before transmission begins, a reset occurs. If the transfer has begun, then regardless of the state of the button, it will be completed completely. If more than one Z or X button is pressed at the same time, the generator will not start.

To enable single system mode, the SSM pin must be high and the system address must be set with the appropriate jumper or switch. In this mode, the X-lines of the transmitter are in a high state during rest. At the same time, the Z-lines are turned off to prevent current consumption. In the first of two scan cycles, the system address is determined and stored in a latch register. In the second cycle, the command number is determined. This command is sent along with the system address stored in the latch register. If there is no Z-DR jumper, then no codes are transmitted.

If the button is released between code transmissions, a reset occurs. If the button is released during the debounce procedure or while the sensor is being scanned, but before a button press is detected, a reset also occurs. Outputs DR0 – DR7 have an open drain, and the transistors are open at rest.

The RC-5 code has an additional control bit that is inverted each time the button is released. This bit informs the decoder whether the button is being held down or a new press has occurred. The control bit is inverted only after a completely completed transmission. Scanning cycles are performed before each sending, so even if you change the pressed button to another during the sending of a parcel, the system number and commands will still be transmitted correctly.

The OSC pin is a 1-pin oscillator input/output and is designed to connect a ceramic resonator at a frequency of 432 KHz. It is recommended to connect a resistor with a resistance of 6.8 Kom in series with the resonator.

Test inputs TP1 and TP2 must be connected to ground during normal operation. When the logic level on TP1 is high, the scanning frequency increases, and when the logic level on TP2 is high, the frequency of the shift register is increased.

At rest, the DATA and MDATA outputs are in the Z-state. The pulse sequence generated by the transmitter at the MDATA output has a filling frequency of 36 kHz (1/12 of the clock generator frequency) with a duty cycle of 25%. The same sequence is generated at the DATA output, but without padding. This output is used when the transmitter chip acts as a controller for the built-in keyboard. The signal at the DATA output is completely identical to the signal at the output of the remote control receiver microcircuit (but unlike the receiver, it does not have inversion). Both of these signals can be processed by the same decoder.

The transmitter generates a 14-bit data word, the format of which is as follows:

· 2 start bits.

· 1 control bit.

· 5 bits of system address.

· 6 bit commands.

Figure 2. RC-5 code data word format.

The start bits are for setting the AGC in the receiver IC. The control bit is a sign of a new press. The clock duration is 1.778 ms. As long as the button remains pressed, a data word is transmitted at intervals of 64 clock cycles, i.e. 113.778 ms (Fig. 2). To ensure good noise immunity, two-phase coding is used (Fig. 3).

Figure 3. Coding "0" and "1" in RC-5 code.

When using the RC-5 code, you may need to calculate the average current draw. This is quite easy to do if you use Fig. 4, which shows the detailed structure of the parcel.

Figure 4. Detailed structure of the RC-5 package.

To ensure the equipment responds equally to RC-5 commands, the codes are distributed in a very specific way. This standardization allows transmitters to be designed to control a variety of devices. With the same command codes for the same functions in different devices, a transmitter with a relatively small number of buttons at a time can control e.g. audio complex, TV and VCR.

System numbers for some types of household equipment are given below:

0 - Television (TV)
2 - Teletext
3 - Video data
4 - Video Player (VLP)
5 - Video cassette recorder (VCR)
8 - Video tuner (Sat.TV)
9 - Video camera
16 - Audio preamp
17 - Tuner
18 - Tape recorder
20 - Compact player (CD)
21 - Turntable (LP)
29 - Lighting

The remaining system numbers are reserved for future standardization or experimental use. The correspondence of some command codes and functions has also been standardized.

Command codes for some functions are given below:

0-9 - Digital values ​​0-9
12 - Standby mode
15 - Display
13 - mute
16 - volume +
17 - volume -
30 - forward search
31 - search back
45 - ejection
48 - pause
50 - rewind
51 - fast forward
53 - playback
54 – stop
55 - entry

In order to obtain a complete IR remote control based on the transmitter chip, you also need an LED driver that is capable of providing a large pulse current. Modern LEDs operate in remote controls at pulse currents of about 1A.

It is very convenient to build an LED driver on a low-threshold (logic level) MOS transistor, for example, KP505A.

An example of a circuit diagram of the remote control is shown in Fig. 5.

Figure 5. Schematic diagram of the RC-5 remote control.

The system number is specified by a jumper between pins Zi and DRj.

The system number will be as follows: SYS = 8i + j

The command code that will be transmitted when a button is pressed that closes line Xi with line DRj is calculated as follows: COM = 8i + j


Common malfunctions.

Problems with wireless remote controls

  • dead batteries (the most common fault);
  • the remote control is filled with some kind of liquid and the buttons either stick or won’t release;
  • the quartz resonator or IR LED fell off (or was damaged) due to the impact;
  • from frequent use, the conductive coating on the buttons themselves (or the conductors under the buttons) wears out;
  • Dirt from hands that gets inside the remote control and accumulates over time.


There is no signal from the remote control.

First, check the health of the batteries. If the voltage on the element is less than 1.3V, it must be replaced. An ammeter measures the “short circuit” current of an element. If it is less than 300 mA, the element must also be replaced.

You can check the functionality of the remote control using any IR photodiode. Under the influence of IR radiation, a voltage appears at the photodiode terminals, which is recorded by an oscilloscope. The photodiode is placed opposite the remote control window. When you press the remote control buttons, pulses with a swing of 0.2...0.5V should appear on the oscilloscope.

Checking the remote control without special tools.
You can turn on the receiver to the “AM” band and press the button on the remote control, bring it close to the receiver, sounds (pulse packets) will be clearly audible from the speaker.
Another simple way to check the functionality of the remote control is as follows: turn on the camera on your mobile phone, point the remote control at the camera and press any button; if the remote control is working, the glow of the infrared emitter will be visible on the phone’s display.

If there is no signal, the remote control is faulty. They open it up. This operation requires certain skills and care so as not to leave scratches on the case or break the latches.

The printed circuit board is inspected, and the keyboard contacts remove traces of dried liquid in the form of a whitish coating from the printed circuit board and the contact field with a cotton swab moistened with alcohol. Cracks on printed conductors are eliminated by soldering jumpers made of tinned wire on top.

They control the quality of the soldering, and the absence of breakage of the leads of the parts, first of all this concerns the IR emitting diode and the quartz resonator. Then the operating modes are checked.

Measure the supply voltage (usually +3V) on the microcircuit. An oscilloscope is used to monitor the operation of the generator when a pair of button contacts is closed. If there is no generation, check the DC voltage +1...1.5V on the quartz resonator. If there is voltage, replace the resonators. If there is no constant voltage, check the serviceability of the microcircuit (by replacing it).

If generation is present, the following malfunctions are possible:

1. A leak appears in one of the pairs of keyboard contacts. Check with an ohmmeter. The resistance between the contacts of a working pair must be at least 100 kOhm. Otherwise, wipe the contacts with a cotton swab moistened with alcohol.

2. There is a leak from the graphite jumpers onto the printed conductors passing under the jumpers. To troubleshoot, the pins of the microcircuit connected to the keyboard contacts are unsoldered one by one. If generation stops when the next pin is unsoldered, check the circuits suitable for this pin. The printed conductor located under the graphite jumper is cut off on both sides and restored with a piece of insulated wire.

3. Dust, dirt, tin and rosin particles get in between the terminals of the microcircuit. Using a hard bristle brush and alcohol, wash the board between the terminals.

4. Microcircuit defect. If, after unsoldering its leads, the resistance of a pair of contacts increases to normal, the microcircuit is faulty. It needs to be replaced.

There is no signal from the remote control, but there is a pulse signal at the output of the microcircuit.

1. There is no supply voltage to the amplifier.

2. One of the amplifier transistors or the IR diode is faulty.

Troubleshooting begins by checking with an oscilloscope the presence of a pulse signal at the cathode of the IR radiation diode. If there is no signal and the DC voltage is zero, check the health of the diode. If it is working properly, and there is a constant voltage, but there is no signal, check the passage of the signal from the output of the microcircuit to the IR radiation diode, the serviceability of the transistors, and the presence of supply voltage.

The most common defects are: a malfunction of the amplifier's output transistor, a violation of the soldering of the terminals of the elements.

There is no signal from the remote control. There is a constant voltage across the IR diode. The batteries are quickly discharged.

The nature of the malfunction indicates that the IR diode is constantly open and a significant current flows through it, leading to the discharge of the elements.

Possible causes of the malfunction:

Breakdown of one of the amplifier transistors. Check with an ohmmeter.

The presence of two or more pairs of closed keyboard contacts. Check with an ohmmeter.

The microcircuit is defective. Check by replacement.

When the keyboard buttons are not pressed, a command is constantly received from the remote control.

Possible causes of the malfunction:

1. Reducing the insulation resistance between the terminals of the microcircuit or the contacts of the contact field. Eliminate by washing with alcohol.

2. Leakage from the graphite jumper onto the printed conductor running underneath it. The defective conductor is cut off at both ends and a piece of insulated wire is soldered on top.

3. The microcircuit is defective. Check by replacement.

One or more commands are not received from the remote control.

The cause of the defect may be an increase in the resistance of the closing contacts of the keyboard, dirt on the contact field, cracks on the board, or a malfunction of the microcircuit.

Use an ohmmeter to check the resistance of the conductive rubber contacts on the keyboard. For serviceable contacts it should be in the range from 2 to 5 kOhm. If the resistance exceeds 10 kOhm, the contacts are faulty. Before changing the entire rubber, you can try to restore the faulty contacts. To do this, the rubber keyboard is first cleaned of dirt by washing it under running hot water with soap and a brush. The faulty contact is then applied to a piece of writing paper and rubbed across it with a little force. Due to the roughness of the paper, a thin layer of dirt and oxides is removed from the contact. It is possible to use fine-grained sandpaper.

Another way to restore functionality is to stick circles of conductive rubber onto the faulty contacts. They are included in special repair kits for remote control units available for sale. Good results are obtained by gluing circles made of metal foil (from cigarettes). The paper-based foil provides a reliable adhesive connection to the rubber. Breaks in the conductors are eliminated by soldering jumpers. Cracks in the contact field are repaired by applying a layer of conductive adhesive (commercially available).

The remote control emits a command, but the TV does not respond to it. The TV is working fine.

Possible causes of the malfunction: a defect in the quartz resonator or microcircuit.

Check by replacement.

Common chipsP DU

8U5800

М3005А8

M708

RC005HC

SAF1039

U327

With LA 3117

M3006LAB

M709

SAA1 124

SKC5401

UM400

DMC6003

M50115

M710

SAA1 250

SL490

mPD660

DYC-R02

M50119

MS144105

SAA3004

SN76881

IX0733PA

M50460

MS14497

SAA3006

STV3021

KS51800

M50461

MN6027

SAA3007

T8909

KS51810

M50462

MN6030B

SAA3008

T8813

LC7462

M50560

NEC1986

SAA3010

TC9012F-011

M3004AV

N58484P

RSA8521

SM3021

U321


Story

One of the earliest remote control devices was invented and patented by Nikola Tesla in 1893.
In 1903, the Spanish engineer and mathematician Leonardo Torres Quevedo presented the Telekino at the Paris Academy of Sciences, a device that was a robot that carried out commands transmitted via electromagnetic waves.


Remote control Zenith Space Commander 500, 1958
The first remote control for controlling a television was developed by the American company Zenith Radio Corporation in the early 1950s. It was connected to the TV with a cable. In 1955, the Flashmatic wireless remote control was developed, based on sending a beam of light towards a photocell. Unfortunately, the photocell could not distinguish the light from the remote control from light from other sources. In addition, it was necessary to point the remote control precisely at the receiver.

Remote control Zenith Space Commander 600
In 1956, Austrian-American Robert Adler developed the Zenith Space Commander wireless remote control. It was mechanical and used ultrasound to set the channel and volume. When the user pressed the button, it clicked and struck the plate. Each plate produced noise of a different frequency, and the television circuitry recognized this noise. The invention of the transistor made it possible to produce cheap electric remotes that contain a piezoelectric crystal that is powered by an electric current and oscillates at a frequency exceeding the upper limit of human hearing (though audible to dogs). The receiver contained a microphone connected to a circuit tuned to the same frequency. Some problems with this method were that the receiver could be triggered by natural noise and that some people could hear high-pitched ultrasonic signals.

In 1974, GRUNDIG and MAGNAVOX released the first color TV with an infrared microprocessor control. The TV had an on-screen display (OSD) - the channel number was displayed in the corner of the screen.
The impetus for more sophisticated types of remote controls came in the late 1970s when Teletext was developed by the BBC. Most remote controls sold at the time had a limited set of functions, sometimes only four: next channel, previous channel, volume up or down. These remote controls did not meet the needs of teletext, where pages were numbered with three-digit numbers. The remote control, which allowed you to select a teletext page, had to have buttons for numbers from 0 to 9, other control buttons, for example to switch between text and image, as well as regular television buttons for volume, channels, brightness, color. The first televisions with teletext had wired remotes for selecting teletext pages, but the growth in the use of teletext showed the need for wireless devices. And BBC engineers began negotiations with television manufacturers, which led in 1977-1978 to the appearance of prototypes that had a much wider range of functions. One of the companies was ITT, the infrared communication protocol was later named after it.
Apple's Stephen Wozniak founded CL9 in the 1980s. The company's goal was to create a remote control that could control multiple electronic devices. In the fall of 1987, the CORE module was introduced. Its advantage was the ability to “learn” signals from different devices. It also had the ability to perform certain functions at designated times thanks to a built-in clock. It was also the first remote that could be connected to a computer and loaded with updated software code. CORE hasn't had much of an impact on the market. It was too difficult to program for the average user, but it received rave reviews from people who were able to figure out its programming. These obstacles led to the dissolution of CL9, but one of its employees continued the business under the Celadon brand.
By the early 2000s, the number of household electrical appliances increased dramatically. To control a home theater, you may need five or six remote controls: from a satellite receiver, VCR, DVD player, television and sound amplifier. Some of them need to be used one after the other, and due to the fragmentation of control systems, this becomes cumbersome. Many experts, including renowned usability expert Jakob Nielsen and the inventor of the modern remote control, Robert Adler, have noted how confusing and clunky it can be to use multiple remotes.
The advent of PDAs with an infrared port made it possible to create universal remote controls with programmable control. However, due to its high cost, this method has not become very widespread. Special universal learning control panels have not become widespread due to the relative complexity of programming and use.



Sources.

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 previously higher quality electronic components were used in household appliances. 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.


For example, we take the T2 digital television set-top box, controlled by a 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.