IR remote control has invaded everyday life and saves us a lot of time. Unfortunately, far from all electrical appliances are equipped with remote control, in particular, light switches. The proposed device will help make their management more convenient.
The switch is controlled by an IR pulse transmitter (remote control), at the command of which the lighting lamp turned off at the moment it is applied will be turned on, and vice versa. An additional IR transmitter is built into the device, which eliminates the need to constantly carry the remote control with you or spend time looking for it. It is enough to bring your hand to the switch at a distance of about ten centimeters and it will work.
The switch responds to pulsed IR radiation without deciphering the code contained in it. Therefore, any remote control from an imported or domestic electronic device (for example, a TV) is suitable, and you can press the button of any command. You can also make a home-made remote control, for example, according to the scheme given in the article by Yu. Vinogradov "IR sensor in a security alarm" ("Radio", 1996, No. 7, p. 42, Fig. 2). There you can also find a drawing of the printed circuit board and recommendations for the manufacture of the device.
The diagram of the simplest version of the control panel is shown in fig. 1. This is a pulse generator on transistors of various structures, the load of which is the radiating diode IR of the AL147A range. The generator is powered by three or four galvanic cells, the command is given by briefly pressing the SB 1 button.
The switch circuit is shown in fig. 2. The IR pulse receiver is assembled according to a scheme similar to that used in the control units of the Rubin and Temp TVs. On transistors VT1 - VT4, a pulse amplifier is assembled, into which the received IR radiation is converted by the photodiode VD1 - FD265 or any other sensitive to IR rays. Further, the received signal passes through an active filter with a double T-bridge, assembled on a VT5 transistor. The filter eliminates interference from lighting lamps, the radiation of which captures the IR region of the spectrum and is modulated by twice the frequency of the AC mains. The sometimes possible self-excitation of this filter is eliminated by replacing the transistor with another one with a lower h21E value.
(click to enlarge)
The filtered signal, passing through the limiting amplifier on the VT6 transistor and the DD1.1 element, enters the drive (VD4 diode and R19C12 circuit). The parameters of the storage elements are chosen in such a way that the capacitor C12 has time to charge up to the level of operation of the element DD1.2 only in three to six received pulses. This prevents the switch from being triggered by single light pulses: photographic flash lamps, lightning discharges. The discharge of the capacitor C12 takes 1 ... 2 s.
The node on the logical elements DD1.2, DD1.3, DD1.6, thanks to the feedback through the capacitor C13, generates pulses with steep level drops coming to the counting input of the trigger DD2. With each of them, the trigger changes state. At log. 1 at pin 1 of the trigger open transistors VT9, VT10 and trinistor VS1. The EL1 lamp circuit is closed, the lighting is on. The glow of the two-color LED HL1 is green. Otherwise (log. 1 at pin 2 of the trigger), the lighting is off, the glow of the HL1 LED is red. The trigger pulse generated by the C19R24 circuit leads to the same state. This eliminates the spontaneous switching on of lighting after a power outage.
The built-in IR transmitter - assembled on the elements DD1.4, DD1.5 pulse generator with a frequency of 30 ... 35 Hz - allows you to use the switch without having a remote control in your hands. The emitting diode BI1 is installed next to the photodiode VD1, but is separated from it by an opaque partition. The radiation of the diode BI1 is directed in the direction from which the photodiode receives it. The switch must operate from the IR pulses of the built-in transmitter, reflected from the palm, brought to a distance of 5 ... 20 cm. The power of the emitted pulses required for this is set by changing the value of the resistor R20.
(click to enlarge)
Brief summary.
Arduino + Bp + Relay + photodetector = control of the light in the room from any remote control that is at hand with minimal labor and money.
Chapter 1. As an introduction.
What will be discussed below was conceived a year ago, done six months ago and has not been brought to its logical conclusion so far due to elementary laziness:
waiting for repairs in the room,
every thing must be aged before use,
whoever understands life is in no hurry.
So, after understanding what was planned a year ago, the necessary components and a soldering iron were ordered for Ali. When everything arrived, I ordered more tin and flux in order to delay the start of work thoroughly to prepare with a clear conscience. Having received them, I realized that I simply needed a “third hand” with a magnifying glass for the comfortable implementation of a great idea. When I received this as well, I remembered in time that I would need a pull-up resistor and a set of resistors was ordered for all occasions. After receiving the resistors, my conscience firmly pinned me to the wall - it's time, brother, to do the job, half a year has already passed.
Everything is ready to start work
I needed:
Here I would like to caution. Do not buy any type, the circuit will not work. Due to poor-quality power, the codes will not be recognized, checked. Look for the recommended PSU, this one works great.
This is about consumables. And I also bought:
(It heats up quickly, there is a regulator, a ceramic heater and does not slip in the hand and from the stands due to the rubber spacer worn on the middle part)
(Tinned, works well. Too bad there is no sting with a groove inside)
(Very liked when soldering)
(Works well and, finally, almost the same smell of rosin from childhood)
(I checked selectively a couple of dozen - the deviation from the nominal value is no more than 2%)
(Great soldering help!)
P.S. I bought all this, except for the correct PSU, from these sellers, but a year ago and at completely different prices.
Chapter 2 Implementation.
The material I offer is based on two powerful philosophical principles: Laziness is the engine of progress and Occam's Razor, which stands for something like “do not multiply the essence beyond what is necessary” or translated into folk “the simpler the better”. Having summed up such a powerful scientific foundation, I will begin my story.
Considering various crafts such as “Smart Home”, I was surprised to find that the most archaic (yes, simply the most necessary!) Solution for me, a true lazy associate of progress, is not. All the proposed solutions, alas, contradict one of the above principles or both at once.
So, we will talk about turning on and off the light in the room using the remote control. Wait a minute to raise a cry - "Like, there are as many such decisions as you want." Now I will explain why none of them suited me.
The decision to buy a switch with a radio channel and a special remote control is simply ridiculous. Sometimes I can’t find a normal remote here, and this one, milipestric, will be lost instantly. Mounting on the wall of a backup switch with a radio channel for the main one did not work due to the presence of a carpet on the wall and the second philosophical principle.
That's why first task it will sound like this for me - the light control should occur from ANY available remote control that is at hand (from a TV, receiver, kondeya, etc.). There are always consoles and AT LEAST ONE OF THEM is at hand.
Task two- the usual switch should remain in place and perform its functions in the same way as before, since, when entering a dark room, we still do not have a remote control in our hands. I don’t want to install capacitive and other stray things, let the switch remain what it was, I’m used to this. In the end, this is the fulfillment of both fundamental principles and elementary savings.
The tasks have been set. We decide.
For those who did not open the first spoiler, I repeat.
We will need:
1. IRDA receiver;
2. Brain (Arduino Nano);
3. Actuator (Relay);
4. Power supply for all of the above.
Due to their size, all modules will fit in the switch box (if there is not enough space, we will hollow out as much more as necessary in the wall, having straightened the box). There was one ambush here - in the switch box I didn’t have a “zero” wire to power the PSU (it happens like that :)). But, since repairs are still expected in the room - it doesn’t matter, the necessary wire will be connected in due time (reinforced concrete argument for conscience!). I didn’t make a hole for the phototransistor in the switch, because I chose the right switch, which has “neon inside”. Accordingly, there is a window with an orange piece of glass. Here, in front of this window, I glued a phototransistor from the inside. You can also bring out the LED from the relay there, which will completely replace the functionality of the neon, which I threw out as unnecessary.
The logic of operation will be as follows: clicking the switch will invert the state of the lamp in the chandelier. Those. if the lamp was off, it will turn on and vice versa. Pressing a programmed button on one of the available remotes will also invert the lamp state. The fact that now the position of the switch key does not depend on the state of lighting does not bother me, I still never remember these positions. What is important - if there is a sudden power outage, then when it resumes, the switch will be in a guaranteed off state, because. the Arduino will reset and initialize when power is applied.
We begin to collect the scheme. Now the switch will only supply one or zero to the Arduino digital input, and the relay will produce its own power phase switching. On the other input of the Arduino, we will start a scarf with a phototransistor.
We write an intermediate sketch to determine the codes of the desired remote control buttons, press the selected button on each remote control, get the codes and write these codes into the final sketch.
Having assembled the circuit, we make sure that it works, we isolate all the components (heat shrink, epoxy, blue electrical tape ... (underline as necessary)) and place it all in the switch box.
Photo, sketches, scheme, video
Let's assemble a temporary hut on a breadboard for reading codes from remotes and debugging the final sketch. It makes no sense to draw a diagram for connecting a computer to Arduino because of the huge variety of USB_to_COM adapters, everyone will find their own version on the internet. And connecting the photodetector to the same legs as in the diagram below. 
There is no switch in this circuit yet, but it is not needed now. We write a sketch, upload and catch button codes from different remotes. I chose the RECORD button that I did not use everywhere. It is she who will control the light from each of the remotes. 
We catch the result in our virtual Com port. 
Yes, there are codes. Now let's write the final sketch, upload it to Arduino, remove the already unnecessary USB_to_COM adapter and add a switch to the circuit. It should be clarified here that in one of its positions, the switch will supply 5v to leg #2 of the Arduino. But in order not to catch a false signal, you must use a pull-up resistor. The theory tells us that this is implemented in the Arduino itself and in the sketch I give the command to turn it on, but I played it safe and added a real 10k resistor, it won’t get worse, but I’m calmer. And I also unsoldered the phototransistor from his handkerchief and lengthened his legs with wires, since the handkerchief did not fit into the place of the torn neon, but one phototransistor stood up perfectly. I grabbed it with superglue. 
And here is the scheme of this economy, where Grd is the earth: 
And this is the final sketch for 4 of my consoles: 
And this is what a switch with a neon window looks like. 
As you can see, the window is built into the movable part of the switch, namely the key, and the phototransistor is fixed to the frame. However, this does not in any way affect the stability of the circuit in operation.
And finally, a video of the circuit in action:
In the video, the operation of the circuit can be determined by turning on the LED on the relay. I did not connect the lamp to the relay, because. earlier I checked that these relays hold 300 watts perfectly. I've been using them for many years and they work great.
In conclusion, I want to note that the remotes work confidently from any distance in the room. It makes no sense to solder the Arduino tightly, because. the filling will be motionless in the wall - i.e. no vibration. But remotes don't last forever. Some may change, new ones may be added. Therefore, I leave the opportunity to correct the sketch code, connect a laptop to the Arduino and upload the code in a new way. And yet, in the video, the LED with the relay is not soldered, but in general it can be unsoldered, the legs lengthened and glued together with a phototransistor to imitate neon. But I'm not sure yet that I want another indicator to glow at night, and the beam of the remote control will find the switch even without backlighting.
Chapter 3 Ready!
Now, before going to bed, turning off the TV, I do not need to get out from under the covers and go turn off the light, but just press the magic button on the same remote control. It is much more pleasant to get up in the morning for work by turning on the light from the remote control, and not to wander in the dark to the switch, risking stepping on something.
This is how my story should have ended, but everything is still on the shelf. Because now I'm waiting for the repair. With a completely clear conscience.
P.S. I may not know how long all this may lie, but I did not wait for the repair, but decided to publish the material now. Suddenly someone will be interested ...
I plan to buy +89 Add to favorites Liked the review +72 +162The proposed device is designed to turn on and off (including remote) incandescent lamps, heaters and other devices powered by a 220 V household network and representing a purely active load with a power of up to 500 W. The switch circuit is shown in Fig.1.
An alternating voltage of 220 V through the fuse FU1 is supplied to the power unit, assembled from the elements VD3, VD4, C3, C5, C7, R7 and R9. A stabilized voltage of 5 V from the capacitor C5 feeds the microcontroller DD1 and the photodetector B1. The microcontroller, working according to the program written to it, analyzes the signals coming from the photodetector to the RB5 input and from the SB1 button to the RB1 input, as well as from the network voltage zero-phase sensor (resistor R6, diodes VD1, VD2) to the RA1 input. The signals generated at the outputs RB0 and RB4, the microcontroller controls the triac VS1 and the LED HL1, respectively. The switch changes its state to the opposite each time you press the SB1 button or the button on the remote control. Two program options are offered. Working on the first of them (file irs_v110.hex), the microcontroller remembers the current state of the switch and, in the event of a temporary power outage, restores this state when it is resumed. When using the second version of the program (file irs_v111.hex), restoration of the mains voltage always switches the circuit breaker to the off state. LED HL1 lights up when the load circuit is open. This is useful when controlling lighting fixtures. The scheme of the remote control switch is shown in Fig.2.
It is powered by two AAA galvanic cells. When you press the SB1 button, a pulse generator with a duration of about 18 ms, assembled on logical elements DD1.1 and DD1.2, starts working. These pulses control the 36 kHz pulse generator on the elements DD1.3, DD1.4. Packets of pulses from the output of this generator are fed to the gate of the transistor VT1, in the drain circuit of which an IR emitting diode VD1 is connected. Establishing the remote control comes down to setting the generator on the elements DD1.3, DD1.4 to a frequency of 36 kHz (the resonant frequency of the photodetector B1 in the switch) by selecting resistor R4. When properly configured, the maximum remote control range of the circuit breaker is achieved. The circuit board of the switch is shown in fig. 3.
The triac VT137-600 is mounted on a heat sink made of an aluminum plate measuring 65x15x1 mm. A replacement for this triac can be selected from among similar devices of the VT136, VT138 series. The BZV85C5V6 zener diode is replaced by another small-sized one with a stabilization voltage of 5.6 V, for example, KS156G. Instead of the TSOP1736 photodetector, another of the TVs and other household electronic devices used in remote control systems will do. The center frequency of the passband of such a photodetector may lie in the range of 30...56 kHz, so the remote control will have to be tuned to this frequency. If it is necessary to expand the sensitivity zone of the switch in the horizontal plane, instead of one photodetector, two can be installed, pointing them in different directions. In this case, conclusions 1 and 2 of two photodetectors are connected in parallel directly, and conclusion 3 is connected through resistors with a nominal value of 1 kOhm. The common point of the resistors is connected to pin 3 of block X1, and the resistor R3 in the switch is replaced with a jumper. The printed circuit board of the remote control is made according to the drawing shown in fig. 4.
Here, as VD1, you can use any IR emitting diode from the remote control of a household appliance. It is undesirable to replace the HEF4011 chip with a similar domestic K561LA7. When the supply voltage is low, it works unstably. On fig. 5 shows the appearance of the switch boards and the remote control.
Radio №5, 2009
List of radio elements
| Designation | Type | Denomination | Quantity | Note | Shop | My notepad | |
|---|---|---|---|---|---|---|---|
| Circuit breaker | |||||||
| DD1 | MK PIC 8-bit | PIC16F628A | 1 | To notepad | |||
| VD1, VD2 | Diode | KD522B | 2 | To notepad | |||
| VD3 | rectifier diode | 1N4007 | 1 | To notepad | |||
| VD4 | zener diode | BZV85-C5V6 | 1 | KS156G | To notepad | ||
| VS1 | Triac | BT137-600 | 1 | To notepad | |||
| C1 | 47uF 10V | 1 | To notepad | ||||
| C2 | Capacitor | 0.022uF | 1 | To notepad | |||
| C3 | Capacitor | 0.1uF | 1 | To notepad | |||
| C4, C6 | Capacitor | 22 pF | 2 | To notepad | |||
| C5 | electrolytic capacitor | 470uF 16V | 1 | To notepad | |||
| C7 | Capacitor | 0.47uF 630V | 1 | To notepad | |||
| R1, R5 | Resistor | 10 kOhm | 2 | To notepad | |||
| R2 | Resistor | 220 ohm | 1 | To notepad | |||
| R3 | Resistor | 1 kOhm | 1 | To notepad | |||
| R4, R8 | Resistor | 100 ohm | 2 | To notepad | |||
| R6 | Resistor | 4.7 MΩ | 1 | 0.5W | To notepad | ||
| R7 | Resistor | 47 ohm | 1 | 1 W | To notepad | ||
| R9 | Resistor | 300 kOhm | 1 | 0.5W | To notepad | ||
| IN 1 | Photodetector | TSOP1736 | 1 | To notepad | |||
| HL1 | Light-emitting diode | AL307BM | 1 | To notepad | |||
| ZQ1 | Quartz | 4 MHz | 1 | To notepad | |||
| FU1 | Fuse | 5 A | 1 | To notepad | |||
| SB1 | Button | 1 | To notepad | ||||
| X1 | Connector | 1 | To notepad | ||||
| X2 | Connector | 1 | To notepad | ||||
| Circuit breaker remote control | |||||||
| DD1 | Chip | HEF4011 | 1 | To notepad | |||
| VT1 | Field-effect transistor | KP505A | 1 | To notepad | |||
| C1 | electrolytic capacitor | 100uF 6.3V | 1 | To notepad | |||
| C2 | Capacitor | 0.047uF | 1 | To notepad | |||
| C3 | Capacitor | 47 pF | 1 | ||||
This type of lighting is actively used in residential, office and even industrial premises. The most popular today are control systems implemented using radio switches, motion sensors, controllers with control panels, smartphones and computers. Modern technologies allow you to manage or on the adjacent plot, being hundreds of kilometers away from them. Some of them will be discussed in the article.
Remote Control Advantage
The use of remote control devices allows you to solve a number of problems:
- Save energy;
- Make the process of turning on / off lamps as comfortable as possible;
- Protect your home or apartment from intruders (presence effect).
Types of remote control
Remote turning on of light can be wired and wireless, manual and automatic, with the ability to manipulate light from devices operating on the principle of emitting and receiving waves of certain frequencies: infrared, microwave, radio frequency, sound, ultrasonic, voice (control of specific commands). In this article, we will dwell on lighting control using various types of radiation, voice and sound commands.
Infrared and radio wave control of light from the remote control
Infrared lighting control using a remote control is extremely rare. Basically, such systems operate on the principle of signal transmission over a radio channel. To be able to manipulate light devices using an IR beam, a lighting remote control unit, for example BM8049M, is connected to the circuit break. It allows you to turn on the lamp switch with a regular TV remote control. To do this, point the remote control at the unit, press any key (which is not used to switch channels), after which the command is recorded in memory and now you can control the inclusion of the light without getting up from the sofa.
The main disadvantages of using IR light remote controls are the need for their accurate aiming at the signal receiver, since they only work within the line of sight, and the short range of the beam, but in this case repeaters can be used.
Much more widespread are light control systems using a remote control, in which a signal is transmitted from a control device to a controller that regulates the process of turning on / off the light at a certain radio frequency.
Radio control of light is more in demand for several reasons:
- The ability to control the light not only with the remote control, but also with a computer, smartphone and other devices;
- Signal range - about 100 meters in the absence of obstacles, 15-25 meters in the presence of obstacles;
- The possibility of installing signal amplifiers and repeaters for better transmission of commands from the control device.
Remote lighting control system via radio channel using a remote control consists of:
- Console;
- battery;
- Remote control controller connected to the network and load.
Install the controller into the wall or glass of the chandelier (see photo). It can control incandescent lamps, compact and conventional fluorescent, halogen, LED lamps, and not only single lamps, but also their group.
Overview of lighting remote control units, made in China, using a remote control, via radio, video:
Remote control of light with infrared and radio switches
Infrared switches are a rarity in the lighting market, as it is more reasonable to control the light using radio devices. One of the most popular switches is "Sapphire" by Nootekhnika (Belarus). The same company produces a variety of radio lighting control devices, including those mentioned below. The switch is controlled by any remote control, for example, television or manually. The signal is received by a receiver located inside the device on the touch panel. A light switch with a remote control is shown in the photo.
Overview of the IR switch "Sapphire", video:
A light switch with a remote control is placed in any place convenient for them, power units - in a junction box or a glass of a chandelier.
An example of "binding" a lighting control unit to a radio switch, video:
Using sensors to control lighting
In the lighting market, various motion sensors are widely represented for remote control of lighting. The most common of these are infrared. They are devices that close or open the lighting circuit with an increase in the level of infrared radiation in their "visibility" zone. As soon as a person or animal enters the field of action of the sensor, whose body temperature is higher than the background temperature, the light turns on. As soon as a person leaves the sensor's coverage area or is in a stationary position for several seconds, the light turns off. Motion sensors are mounted most often in the entrances, above the front door, less often - inside the apartment.
Disadvantages and advantages of infrared sensors
The disadvantages of using motion sensors include the possibility of false positives (reaction to warm air, sunlight), deterioration of outdoor performance due to precipitation, lack of operation of the device in the case when a person’s clothing does not transmit infrared radiation, constant switching off of the light after 10-15 seconds, as soon as motor activity decreases.
The advantages of sensors include the ability to control the consumption of electrical energy and, as a result, reduce cash costs, safety for human health, and ease of use.
Connecting motion sensors is not difficult; the installation diagram below is very common. For its implementation, a three-wire wire is required, with which the lighting control device is powered from the network and connected to the load. The phase wire of the network is connected to the phase wire of the sensor. Zero conductors of the lamp, power supply and sensor are connected together. The luminaire is connected by a phase wire to the remaining wire of the sensor.
Selection of infrared motion sensors
When choosing IR sensors, pay attention to the following parameters:
- Place of application. Sensors are available with degrees of protection from IP20 to IP 55 and are built-in and mounted. For use in an apartment, a built-in sensor looks more profitable, and the degree of protection practically does not play a role. To install the device on the street or in the entrance, it is better to choose a model with protection against dust and water, mounted on a bracket;
- Maximum range. IR sensors capture changes in background temperature at a distance of 10-20 meters. Those of them that are planned to be installed on the street should have a larger "coverage" radius. Indoors, this parameter is useless;
- detection angle. In the vertical plane, the viewing angle of the sensors is 15-20 degrees, in the horizontal - from 60 to 360 degrees;
- Load power. Before buying a sensor, you need to know the power of the load connected to it and choose a device according to these indicators with a margin.
Using other motion sensors to control the light
In addition to infrared controllers, microwave, sound and ultrasonic, as well as combined sensors are sometimes used to control lighting.
Microwave sensors
Microwave sensors work on the principle of emitting and receiving electromagnetic waves. In normal mode, the frequency and length of the waves emitted and reflected from objects are the same. When a person enters the sensor's coverage area, these parameters change, after which the light circuit switching mechanism is activated. The advantages of microwave sensors are that they are high-precision devices, they work perfectly even in bad weather, and the disadvantages are the possibility of false positives, high price, and harmful radiation for sensors with a large coverage radius.
Ultrasonic sensors
Ultrasonic sensors are similar in principle to microwave sensors. Inside these devices, a generator of sound waves is installed, with a frequency of 20 to 60 kilohertz, which are emitted and reflected from objects located in the field of action of the sensor. When a person or animal enters the coverage radius, the frequency of the sound waves arriving at the sensor changes, which the device immediately registers. Disadvantages of ultrasonic sensors: may not respond to smooth movement, cause discomfort to animals. Advantages of sensors: low cost, they work in conditions of high humidity, temperature changes, they react to movement, regardless of the material of which the person is wearing clothes.
Combined sensors
Combined sensors combine several motion detection technologies. They can use microwave and ultrasonic radiation or infrared and microwave. Such devices most qualitatively perform the tasks assigned to them.
Sound sensors
Sound sensors respond to sudden changes in sound, the level of which is set by changing the sensitivity of the sensor. Most often, the light is turned on and off by clapping your hands. A variety of sound sensors can also be considered voice switches.
Voice control of the light
Voice control of lighting devices in the apartment is implemented using voice sensors-switches, often used in Smart Home systems, as well as computers or smartphones on which a special program is installed.
Light switches with remote control (voice) are divided into two types: with the need to configure and without it. In the first case, you need to teach the device commands to activate, turn on and off the light, in the second case, all commands are already written in memory and indicated in the instructions, you just need to use them to control. Often such switches can be controlled not only by voice, but also by any remote control. These include Jaco and Servi. You can get acquainted with the features of their work on the websites of manufacturers.
In our time, it is almost impossible to imagine equipment without remote control. But, unfortunately, not all devices are equipped with such remotes ...
Chinese manufacturers, however, have already begun to produce chandeliers equipped with radio control panels, but the cost of such devices is quite high.
This article proposes a fairly simple scheme such a switch. Unlike the industrial one, which includes one BIS, it is mainly assembled on discrete elements, which, of course, increases the dimensions, but, if necessary, can be easily repaired. But if you are chasing dimensions, then in this case you can use planar parts. This circuit also has a built-in transmitter (industrial ones do not), which saves you from having to carry the remote control with you all the time or look for it. It is enough to bring your hand to the switch at a distance of up to ten centimeters and it will work. Another advantage is that to DU any remotes from any imported or domestic radio equipment are suitable.
Transmitter
Figure 1 shows a diagram of the emitter of short pulses. This allows you to reduce the current consumed by the transmitter from the power source, which means extending the service life on one battery. On the elements DD1.1, DD1.2, a pulse generator is assembled, following with a frequency of 30 ... 35 Hz. Short, 13 ... 15 μs duration, pulses are formed by the differentiating circuit C2R3. Elements DD1.4-DD1.6 and a normally closed transistor VT1 form a pulse amplifier with an IR diode VD1 on the load.
The dependence of the main parameters of such a generator on the supply voltage Upit is shown in the table.
| Upit, V Iimp, A Ipot, mA |
4.5 0.24 0.4 |
5 0.43 0.57 |
6 0.56 0.96 |
7 0.73 1.5 |
8 0.88 2.1 |
9 1.00 2.8 |
Here: Iimp is the amplitude of the current in the IR diode, Ipot is the current consumed by the generator from the power source (with the value of resistors R5 and R6 indicated on the diagram).
Any remote control from domestic or imported equipment (TV, VCR, music center) can also serve as a transmitter.
The printed circuit board is shown in Fig.3. It is proposed to make it from double-sided foil fiberglass with a thickness of 1.5 mm. The foil on the side of the parts (not shown in the figure) performs the function of a common (negative) wire of the power source. Areas 1.5–2 mm in diameter are etched around the holes for passing the leads of parts in the foil. The conclusions of the parts connected to the common wire are soldered directly to the foil of this side of the board. Transistor VT1 is attached to the board with an M3 screw, without any heat sink. The optical axis of the IR diode VD1 must be parallel to the board, and 5 mm apart from it.
Receiver
The receiver is assembled according to the classical scheme adopted in the Russian industry (in particular, in Rubin, Temp TVs, etc.). Its circuit is shown in Figure 2. IR radiation pulses fall on the IR photodiode VD1, are converted into electrical signals and amplified by transistors VT3, VT4, hard labor is connected according to a common emitter circuit. An emitter follower is assembled on the transistor VT2, matching the resistance of the dynamic load of the photodiode VD1 and the transistor VT1 with the input impedance of the amplifier stage on the transistor VT3. Diodes VD2, VD3 protect the pulse amplifier on the transistor VT4 from overloads. All receiver input amplifier stages are covered by deep current feedback. This provides a constant position of the operating point of the transistors regardless of the external illumination level - a kind of automatic gain control, which is especially important when the receiver is operated in rooms with artificial lighting or outdoors in bright daylight, when the level of extraneous IR radiation is very high.
Next, the signal passes through an active filter with a double T-shaped bridge, assembled on a VT5 transistor, resistors R12-R14 and capacitors C7-C9. Transistor VT5 must have a current transfer coefficient H21e = 30, otherwise the filter may start to be excited. The filter cleans the transmitter signal from AC mains interference emitted by electric lamps. Lamps create a modulated radiation flux with a frequency of 100 Hz and not only in the visible part of the spectrum, but also in the IR region. The filtered signal of the code message is formed on the transistor VT6. As a result, short pulses are obtained on its collector (if received from an external transmitter) or proportional with a frequency of 30 ... 35 Hz (if received from a built-in transmitter).
The pulses coming from the receiver are fed to the buffer element DD1.1, and from it to the rectifier circuit. The rectifier circuit VD4, R19, C12 works like this: When the output of the element is logical 0, then the VD4 diode is closed and the capacitor C12 is discharged. As soon as pulses appear at the output of the element, the capacitor begins to charge, but gradually (not from the first pulse), and the diode prevents it from discharging. Resistor R19 is chosen in such a way that the capacitor has time to charge up to a voltage equal to logical 1 with only 3 ... 6 pulses coming from the receiver. This is another protection against interference, short IR flashes (for example, from a camera flash, lightning, etc.). The discharge of the capacitor occurs through the resistor R19 and takes 1 ... 2 s in time. This prevents crushing and arbitrary switching on and off of the light. Next, an amplifier DD1.2, DD1.3 with capacitive feedback (C3) is installed to obtain sharp rectangular drops at its output (when turned on and off). These drops are fed to the input of the divider by 2 trigger assembled on the DD2 chip. Its non-inverted output is connected to an amplifier based on the VT10 transistor, which controls the VD11 thyristor, and the VT9 transistor. Inverted is applied to the transistor VT8. Both of these transistors (VT8, Vt9) serve to ignite the corresponding color on the VD6 LED when the light is turned on and off. It also performs the function of a "beacon" when the light is off. An RC circuit is connected to the input R of the divider trigger, which resets. It is needed so that if the voltage in the apartment is turned off, then after turning on the light does not accidentally light up.
The built-in transmitter is used to turn on the light without a remote control (when bringing your palm to the switch). It is assembled on elements DD1.4-DD1.6, R20-R23, C14, VT7, VD5. The built-in transmitter is a pulse generator with a repetition rate of 30 ... 35 Hz and an IR LED is connected to the load by hard labor. The IR LED is installed next to the IR photodiode and must be directed in the same direction with it, and they must be separated by an opaque partition. Resistor R20 is selected in such a way that the actuation distance, when the palm is raised, is 50 ... 200 mm. In the built-in transmitter, you can use an IR diode of the AL147A type or any other. (For example, I used an IR diode from an old drive, but the resistor R20=68 Ohm).
The power supply is assembled according to the classical scheme on KREN9B and the output voltage is 9V. It includes DA1, C15-C18, VS1, T1. Capacitor C19 serves to protect the device from power surges. The load in the diagram is shown by an incandescent lamp.
The printed circuit board of the receiver (Fig. 4) is made of one-sided foil fiberglass with a size of 100X52 mm and a thickness of 1.5 mm. All parts, with the exception of the diode VD1, VD5, VD8, are installed as usual, the same diodes are installed from the mounting side. Diode bridge VS1 is assembled and discrete rectifier diodes are often used in imported technology. The diode bridge (VD8-VD11) is assembled on diodes of the KD213 series (others are indicated in the diagram), the diodes are soldered one above the other (column), this method was used to save space.
Literature:
1. Radio No. 7 1996 pp.42-44. "IR sensor in the burglar alarm."