IR control of models with your own hands, power section. IR receiver circuit for remote control of electrical appliances

Integrated infrared radiation receivers are widely used in household electronic equipment. In another way they are also called IR modules.

They can be found in any electronic device that can be controlled using a remote control.

Here, for example, is an IR receiver on a TV circuit board.

Despite the apparent simplicity of this electronic component, it is a specialized integrated circuit designed to receive an infrared signal from remote controls. As a rule, an IR receiver has at least 3 pins. One pin is common and is connected to minus «-» food ( GND), the other serves as positive «+» output ( Vs), and the third is the output of the received signal ( Out).

Unlike a conventional infrared photodiode, an IR receiver can receive and process an infrared signal, which is an IR pulse of a fixed frequency and a certain duration - a burst of pulses. This technological solution eliminates random activations that can be caused by background radiation and interference from other devices emitting in the infrared range.

For example, fluorescent lighting lamps with electronic ballast can cause strong interference to the IR signal receiver. It is clear that using an IR receiver instead of a conventional IR photodiode will not work, because the IR module is a specialized microcircuit tailored for specific needs.

In order to understand the principle of operation of the IR module, let’s look at its structure in more detail using a block diagram.

The IR receiver chip includes:

PIN photodiode

Adjustable amplifier

Bandpass filter

Amplitude detector

Integrating filter

Threshold device

PIN photodiode is a type of photodiode in which between the regions n And p there is a region of its own semiconductor ( i-area ). The intrinsic semiconductor region is essentially a layer of pure semiconductor without impurities introduced into it. It is this layer that gives the PIN diode its special properties. By the way, PIN diodes (not photodiodes) are actively used in microwave electronics. Take a look at your mobile phone, it also uses a PIN diode.

But, let's return to the PIN photodiode. In the normal state, no current flows through the PIN photodiode, since it is connected to the circuit in the opposite direction (in the so-called reverse bias). Since under the influence of external infrared radiation in i-areas electron-hole pairs arise, and as a result, current begins to flow through the diode. This current is then converted into voltage and supplied to adjustable amplifier.

Next, the signal from the adjustable amplifier goes to band pass filter. It serves as protection against interference. The bandpass filter is tuned to a specific frequency. Thus, IR receivers mainly use bandpass filters tuned to a frequency of 30; 33; 36; 36.7; 38; 40; 56 and 455 kilohertz. In order for the signal emitted by the remote control to be received by the IR receiver, it must be modulated at the same frequency to which the IR receiver's bandpass filter is set. This is, for example, what a modulated signal from an infrared emitting diode looks like (see figure).

And this is what the signal looks like at the output of the IR receiver.

It is worth noting that the selectivity of the bandpass filter is low. Therefore, an IR module with a 30 kilohertz filter can easily receive a signal with a frequency of 36.7 kilohertz or more. True, at the same time, the distance of reliable reception is noticeably reduced.

After the signal has passed through the bandpass filter, it is sent to amplitude detector And integrating filter. An integrating filter is needed to suppress short single signal bursts that may be caused by interference. Next, the signal goes to threshold device, and then on output transistor.

For stable operation of the receiver, the gain of the adjustable amplifier is controlled by an automatic gain control system ( AGC). Since the useful signal is a packet of pulses of a certain duration, due to the inertia of the AGC, the signal has time to pass through the amplification path and the remaining nodes of the circuit.

In the case when the duration of a burst of pulses is excessive, the AGC system is triggered and the receiver stops receiving the signal. This situation can arise when the IR receiver is illuminated by a fluorescent lamp with an electronic ballast that operates at frequencies of 30 - 50 kilohertz. In this case, the modulated infrared radiation of the lamp’s mercury vapor can pass through the protective bandpass filter of the photodetector and trigger the AGC. Naturally, the sensitivity of the IR receiver decreases.

Therefore, you should not be surprised when the TV photoreceiver does not accept commands from the remote control well. Perhaps he is simply disturbed by the illumination of fluorescent lamps.

Automatic threshold adjustment ( ARP) performs a similar function as the AGC, controlling the threshold of the threshold device. The ARP sets the response threshold level in such a way as to reduce the number of false pulses at the module output. In the absence of a useful signal, the number of false pulses can reach 15 per minute.

The shape of the IR module body helps focus the received radiation onto the sensitive surface of the photodiode. The material of the housing transmits radiation with a wavelength from 830 to 1100 nm. Thus, the device implements an optical filter. To protect the receiver elements from external electric fields, an electrostatic shield is installed in the module. The photo shows IR modules of the brand HS0038A2 And TSOP2236. For comparison, conventional IR photodiodes are shown nearby. KDF-111V And FD-265.

IR receivers

How to check if the IR receiver is working properly?

Since the IR signal receiver is a specialized microcircuit, in order to reliably check its serviceability it is necessary to apply supply voltage to the microcircuit. For example, the nominal supply voltage for “high voltage” IR modules of the TSOP22 series is 5 volts. The current consumption is a few milliamps (0.4 - 1.5 mA). When connecting power to the module, it is worth considering the pinout.

In a state when no signal is supplied to the receiver, as well as in pauses between bursts of pulses, the voltage at its output (without load) is almost equal to the supply voltage. The output voltage between the ground pin (GND) and the signal output pin can be measured using a digital multimeter. You can also measure the current consumed by the module. If the current consumption exceeds the typical one, then the module is most likely faulty.

Read about how to check the serviceability of the IR receiver using a power supply, multimeter and remote control.

As you can see, IR signal receivers used in infrared remote control systems have a fairly sophisticated design. These photodetectors are often used by microcontroller technology enthusiasts in their homemade devices.

A single-channel receiver module with a relay, to be triggered by any standard infrared remote control, provides remote control of any load via an invisible IR channel. The project is based on PIC12F683 microcontroller and TSOP1738 is used as the infrared receiver. The microcontroller decodes the RC5 serial design data coming from the TSOP1738 and provides output control if the data is valid. The output can be set to various desired states using a jumper on the board (J1). There are 3 LEDs on the printed circuit board: power indicator, transmission presence and relay activation. This circuit works with any RC5 remote control for a TV, center, etc.

Features of the circuit

• Receiver power supply 7-12V DC
• Receiver current consumption up to 30 mA
• Range up to 10 meters
• RC5 signal protocol
• Board dimensions 60 x 30 mm

Although it has recently become fashionable to use a radio channel, including Bluetooth, making such equipment yourself is not at all easy. In addition, radio waves are subject to interference, and it’s easy to intercept them. Therefore, the IR signal will be preferable in some cases. Firmware, printed circuit board drawings and full description in English -

Among devices designed for remote control and monitoring, devices using infrared (IR) radiation have a long-standing and honorable place.

For example, the first infrared remote controls appeared in 1974 thanks to Grundig and Magnavox, which released the first TV equipped with such control. Sensors using infrared radiation are widely used in automation.

The main advantage of IR control devices is their low sensitivity to electromagnetic interference and the fact that these devices themselves do not interfere with other electronic devices. As a rule, IR remote control is limited to residential or industrial premises, and the emitter and receiver of IR radiation must be in direct line of sight and directed towards each other.

These properties determine the main scope of application of the devices in question - remote control of household appliances and automation devices over short distances, as well as where non-contact detection of intersection of the linear propagation line of radiation is required.

Even at the dawn of their appearance, devices using IR rays were very simple to develop and use, but nowadays, with the use of a modern electronic base, such devices have become even simpler and more reliable. As you can easily see, even mobile phones and smartphones are equipped with an infrared port for communication and control of household appliances via the infrared channel, despite the widespread use of wireless technologies such as Bluetooth and Wi-Fi.

Master Kit offers several infrared modules designed for use in DIY projects.

Let's consider three devices of varying degrees of complexity and purpose. For convenience, the main characteristics of all devices are summarized in a table located at the end of the review.

1. The infrared barrier is intended for use as a sensor for security systems, during sports competitions as a photo finish, and also for remote control of automation devices at a distance of up to 50 meters.

The device consists of two modules – a transmitter and a receiver. The transmitter is assembled on a dual integrated timer NE556 and generates rectangular pulses with a filling frequency of 36 kHz. The timer has a sufficiently powerful current output to directly control the infrared LEDs connected to it.

A single analogue of the NE556 is the famous integrated timer NE555, which has faithfully served an entire army of radio amateurs for the development of electronic devices for many decades. You can study the timer using examples of 20 electronic circuits developed on the basis of this timer using the “Classics of Circuit Design” design kit from their ABC of an Electronics Engineer series. When assembling the circuits, you don't even need a soldering iron; they are all assembled on a solderless breadboard.

The emitted signal is received by a receiver, the basis of which is a specialized microcircuit, is detected by a peak detector and goes to a current amplifier on a transistor, to which a relay is connected, which allows switching current up to 10A.

The infrared barrier, despite its simplicity, is a fairly sensitive device, and allows you to work with both “transmission” and “reflection” and requires the manufacture of hoods for the transmitter and receiver, eliminating the influence of reflected signals.

An example of using an infrared barrier in conjunction with the “Digital Laboratory” set from the already mentioned ABC of an Electronics Engineer series can be viewed.

1. - This is a light switch controlled by any infrared remote control.

The module allows you to control lighting or other electrical appliances using any button on the remote control.

Typically, every remote control has buttons that are rarely used or not used at all. By using this switch, you can turn on and off a chandelier, fan, etc. from the same remote control with which you control your TV or stereo system.

When power is applied, the module “wait” for 10 seconds to receive a signal corresponding to the selected button on the remote control, and after this time “remembers” the button pressed. After this, to activate the module relay, it is enough to press this button once; when pressed again, the relay will turn off. Thus, a “trigger” type control mode is implemented. The module remains programmed even if its power is turned off.

It should be noted that the module “remembers” its last state when the power is turned off.

The device has an automatic load shutdown mode approximately 12 hours after it is turned on in case you forgot to turn off the load.

The module relay can switch power up to 1500 W.

1. The IR wireless control kit has its own remote control with 4 buttons and 4 control channels of 2000 W each.

Each of the 4 remote control channels operates in “button” mode, i.e. The channel relay is closed while the corresponding button on the remote control is pressed.

Using the module, it is possible to organize reversible control of two brushed electric motors, since each relay has one normally closed (NC) and one normally open (NO) contacts with a common wire.

For ease of use, each channel is equipped with an LED indicating relay activation.

The kit's remote control is powered by a CR2032 element.

Load control with higher power for all devices considered can be achieved using expansion modules:

Up to 4000 W: expansion module will do;

Up to 8000 W: expansion module will do.

Infrared controlled modules

This article provides a diagram of a device for remote lighting control. This device is very convenient because it allows you to control, for example, the lighting in a room without getting up from your chair. The presence of a controller allows you to use the RC5 IR protocol and any combination of remote control buttons for control.

The device consists of a transformerless power supply, microcontroller, and IR receiver. The power part is made of a relay. The brain of the entire design is the PIC12F675 microcontroller. It reads the IR signal received by the TSOP1736 photodetector, decodes it and controls relay P1 through transistor VT1, which in turn switches the light source. The choice of relay type depends on the load power and its supply voltage. KD208 can be used as VD2. To indicate operation, a low-power LED HL1 with a current-limiting resistor R2 is used. The value of resistor R2 is calculated based on the voltage drop across HL1 and the operating current. Again, based on minimizing power consumption, a larger resistor was taken. SB1 is a small-sized button. It is necessary for recording IR commands into the controller memory of any unused IR remote control button and indicating that the lamps are turned on.

After installing the circuit, the printed circuit board must be washed with alcohol and dried. Without inserting the controller into the panel, check the required supply voltages. If everything is fine, remove the voltage and insert the previously programmed microcontroller. Apply the supply voltage again and press the SB1 button, the circuit is ready to receive IR code. Next, press any unused button on the remote control, the HL1 LED should light up (the command has been accepted and decrypted) and immediately press SB1 again - the command code is written into the controller’s memory. The interval between turning on the LED and pressing the button to record the code should be short. All. Now, when you press the button you selected, the light should turn on and off.

Attention! Since the circuit uses a transformerless power supply, touching any part of the circuit may cause electric shock. All connections can be made only after making sure that both power wires are disconnected from the device.

Having assembled the JDM programmer, we begin to search for some easy-to-replicate circuit. Quite often these are banal flashing lights on an LED or a clock on LED indicators, but the first option has almost no practical application, and the second is often not suitable, not because it is undesirable, but because a radio amateur, especially a beginner or living in the outback, does not always have the necessary components (for example, a quartz resonator or LED indicators).

I replaced the TSOP1738 photosensor with a TSOP1736, but you can experiment with similar parts removed from faulty equipment.

The microcontrollers indicated in the diagram are flashed with different firmware - both firmware versions can be downloaded from the site mentioned above.

You can use any relay with a winding voltage of 12 volts.

A little about the remaining details, since the values ​​of some of them are not very clear in the diagram:
C1 - 220 µF 25 V;
C2 - 220 µF, at least 10 V;
C3 - 0.1 μF (here a typo crept into the author’s diagram - the next capacitor, electrolytic, must have serial number 4);
C4 - 4.7 µF 10 V;
R1 - 330 Ohm;
R2 - 1K;
R3 - 4.7 K;
T1 - BC547, KT315 or other similar transistors of the N-P-N structure;
LED - LED of any type and color of your choice;
D1 - 1N4148, 1N4007 or analogues;
Button - without fixation.
Stabilizer - any 5 volt.