An acoustic switch is a very useful thing in household use. This device will add comfort and creativity to your home. With it you can turn the light on and off, or use it for other devices, for example, an electric kettle or a fan.

Such a switch will find application in a situation where a person needs light, but has limited capabilities. All you have to do is clap your hands and the lights will turn on. They are also called cotton sensors.

The operating principle of acoustic switches is to use a microphone with adjustable sensitivity. The microphone turns on or off when sound is detected.

Disadvantages of acoustic sensors

The disadvantages of these sensors stem directly from what they respond to - sound. The selectivity of the microphone is very high and the development of acoustic light switches is progressing, so that modern sensors respond very accurately to a given sound. But in order to produce this sound, you need to know what it is, and this sound will always be a signal to turn it on or off.

The second significant drawback is the sensitivity zone. For a room with large sizes you will have to clap loudly enough, or come closer.

And if you increase the sensitivity, the sensor can respond to similar signals from the next room.

The simplest circuit of an acoustic switch

The simplest effective acoustic switch circuit can be assembled by anyone with the desire and time. Such a switch can be used for various purposes, for example, to turn on and off the lighting in a room using a clap; the same principle of operation and control of any equipment. In general, this acoustic switch is a very useful thing in home use.

This sensor makes it possible to turn on and off power circuits using a clap. Such a device can be used to turn on the light.

It is quite sensitive due to the presence of a double amplifier using low power transistors. It responds well to clap from a distance of five meters from the microphone.

Required parts for assembly

To assemble an acoustic switch with your own hands, you need to take the following parts:

• Resistors (R1-10k, R2-1M, R3-22k, R4-270k, R5-2k, R6-1.8k, R7-330 Ohm, R8-1.5k)
• Transistors (VT1-KT315, VT2-KT315, VT3-3107)
• Capacitors (S1-3200pf, S2-1uF×10v)
• Diodes VD1
• Miscellaneous: M1 - electret microphone, HL1 - LED or relay, contact block.

Acoustic switch device

The microphone amplifier is assembled on two bipolar transistors of the KT 315 series. In order to increase the sensitivity of the microphone, you can use transistors of the KT 368 type or their imported analogues(SS 9018).

The power part of the circuit is a powerful transistor KT 818, which controls the load. If you want to control a large load, you can use a relay with a supply voltage of 3.5 to 15 volts.

When controlling loads with power up to 12 volts, you can remove the relay from the circuit and connect the load instead. If you need to control loads powered by the network, then you definitely need a relay. During the clap, the microphone receives the wave and feeds it to the power amplifier, they take turns amplifying the signal received from the microphone.

Already amplified signal arrives at the base of the switch, its value allows the transistor to operate, and at this moment the junction of the transistor opens and conducts current. It powers the connected load or relay. When there is another clap, the generation is interrupted and the relay is de-energized.

Instructions for making an acoustic switch

First you need to make a printed circuit board. IN printed circuit board There are special holes for the VD1 diode. The diode is necessary to protect transistor VT3 from the EMF of the relay coil. If you want to connect a light load to the switch, you can replace it with a jumper.

After making the board, you need to drill holes and tin it. Next, open the signet in the sprint-layout 6.0 program and follow the location of the parts and solder them in place.

Note!

Looking at the photo of the finished acoustic switch, we see a compact sensor that is easy to install. It is a small board with soldered parts.

When assembling, it is necessary to observe all the ratings of the parts; even a slight slope can lead to incorrect operation of the switch. The device responds not only to pops, but also to any low-frequency noise.

Power comes from the source direct current with voltage from 5 to 12 volts. It is necessary to use stabilized constant voltage sources; when using switching power supplies, the device may not work.

In order to make an acoustic switch with your own hands, you need parts; they can be purchased at any radio store; they are available and inexpensive.

You can use parts soldered from old boards. The circuit is very simple, and even people little familiar with radio electronics, using this diagram will be able to assemble this device.

Photo of an acoustic switch

Note!

Note!

Nowadays, remote control of lighting is becoming popular. You can use a sound or clap switch for this. If the sound is intense enough, equal in strength to clapping your hands, the light turns on or off. If earlier similar electrical circuits assembled by radio amateurs, the device can now be purchased in many electrical goods stores.

Cotton switch model

Connection diagrams

The simplest device, which you make yourself, works from a microphone, amplifying the signal several times. One such scheme is shown in the figure below. All components are easily accessible.

Cotton switch operation diagram

The amplifier consists of two transistors (KT315). The signal from the microphone (M) passes through them, is amplified and goes to the base of a powerful transistor (KT 818). It controls a relay (Rel1) that closes or opens its contact in the power circuit of a lamp or other load: air conditioner, fan, etc. The sensitivity of the device is 4-5 m, which is sufficient for domestic premises. The sound, supplied periodically, alternately connects and disconnects the load from the network.

The circuit is one of the simplest, especially since the microphone can be taken from an old tape recorder or telephone. Distributed electret microphone. One pin is connected to the body (minus). It's easy to call and find. The energy consumption of the device is insignificant, and the supplied voltage is 3.5-16 V.

Instead of a relay you can connect LED lamp small power, which will be the main load. Then the circuit will have no mechanical parts, and its reliability will increase. The light bulb is quite suitable for a night light, lighting a household space, as well as a room where it is difficult to navigate at night, and the main switch is difficult to find.

The switch diagram shown is too simple. You can assemble a more advanced and reliable device using thyristors with your own hands.

Connection diagram for a cotton switch using thyristors

The basis is a trigger made of thyristors (V2), (V3) and a transistor switch (V4). The trigger is connected to a voltage divider consisting of a microphone (B1) and a resistor (R8). The key controls the lamp (H1). The trigger is powered through a diode (V9) and resistors (R9), (R10). The voltage is equalized using a capacitor (C7) and a zener diode (V1).

A stable state of the trigger will be when one of the thyristors is on and the other is off. When served sound signal from the microphone, a pulse appears on the voltage divider, transferring the trigger to another state. The lamp will either turn on or off.

The load power of the switch is about 100 W. If it needs to be increased, more powerful diodes (V5-V8) of the bridge circuit are used, and SCRs are installed on radiators.

Landing lighting

For interfloor lighting, it is advisable to use an acoustic sensor with a photo relay.

Circuit diagram of a switch combined with a photosensor

The photodiode (VD1) forms a voltage divider with a resistor (R2), which forms a voltage divider with it and allows you to adjust the sensitivity of the sensor. If the photosensor is not needed, it is turned off by setting the resistor (R2) to minimum.

The circuit is based on the K176LA7 microcircuit, the elements of which are D1.1-D1.4. D1.1 and D1.2, they are designed to eliminate chattering of the automatic light switch at threshold illumination values.

The sound signal is picked up by an electret microphone and converted into an electrical signal. Then it intensifies bipolar transistors and is fed to logic elements (D1.3) and (D1.4), which generate a pulse lasting about 10 seconds. During this time, the light lamp (La1) remains on. In the daytime, the lamp is turned off by a control signal coming from the output (4) of the element (D1.2).

Automatic soft switch

The switch serves to smoothly turn on the light from an analog microphone signal for a specified time.

Scheme of operation of a smooth acoustic switch

The sound enters the microphone, is converted into an electrical signal and is amplified by passing through operational amplifier(DA1.1), charges the capacitor (C6). When the charge becomes greater than the capacitance (C7), the comparator (DA1.2) switches, and a logical one signal appears at its output instead of zero. As a result, the generator on the transistor (VT1) starts, it supplies pulses that open the triac (VS1), through which power is supplied to the lamp (EL1).

After a certain time, the voltage across the capacitor will decrease. As it decreases, the triac receives control pulses with an increasing phase delay, causing the lamp to turn off smoothly.

Having selected the ratings (C6) and (R5), you can turn on the lamp for up to 3 minutes.

Manufacturers

Cotton switch “Ekosvet”

Reduced prices for electronics make it impractical to make acoustic light switches with your own hands. The Ecolight switch works with all types of 220 V lamps. Specifications:

perceived sound – from 30 to 150 dB;

housing protection level – IP30;

operating temperature – from -200С to +400С;

price – 350 rub.

The device is secured with self-tapping screws to the mounting tabs. The principle of operation is to turn on and off the load with one clap. The switch should not be located in rooms where there may be extraneous sound. False positives are allowed, despite the fact that it is configured primarily for claps.

“Ekosvet” is connected to a 220 V network according to the connection diagram for a smooth acoustic switch shown in the figure above. It is clear that it is associated with a regular switch, which is needed in order to de-energize the circuit and take it out of operation.

Connection diagram for cotton switch “Ekosvet”

“Claps” switch

The modern model of the “Claps” switch is one of the new developments where the sound is processed by a microprocessor. The device is set to several claps and does not respond to other extraneous sounds. In this case, a prerequisite for turning on or off the light is to send signals in a row. In one room you can install several such switches that respond to a certain number of claps. To do this, you need to set a jumper on the electronic board of the device to a certain position. Thus, by supplying the required number of signals evenly following each other, you can control several devices, for example, light sources, a fan, a humidifier, music center and others.

Electrically opening curtains with pops can impress guests. The control device has the size of a matchbox and can easily be hidden in the body of the device or in the socket of a switch. The “Claps Plug” version can easily be used to adapt any household appliance with an electrical cord that will turn on by sound.

Cotton switch “Claps Plug”

Such operation provides better protection against extraneous noise. This model differs from an acoustic switch. Lamps can be any. Compared with previous model, the price of the device is much higher (RUB 2,450).

If the clapper switch provides for smooth switching on of the load, then with fluorescent lamps it won't work. The “Claps” switch can be used with them.

Principle of operation. Video

You can learn about the operating principle and design diagram of the cotton switch from the video below.

When installing and adjusting the cotton light switch, you should follow safety precautions for working with electricity. After installation, you need to set the required sensitivity. The devices operate reliably in rooms where there is no extraneous sound. It is also possible to provide switching to operation from a conventional switch.

In recent years, systems have gained popularity remote control lighting. Sound commands are accepted by the clap switch. When the clap is strong enough, the light turns on or off. The device can be purchased at a store or, if you have sufficient knowledge of the basics of electrical engineering, you can make it yourself.

Application

The light switch claps on and off in response to the noise it makes. The operating algorithm is as follows: the first clap - switching on, the second - switching off.

It is recommended to install devices of this type only in quiet rooms. Premises of this type include bedrooms, storage rooms, utility rooms, and basements. It is irrational to install cotton devices in rooms where there are many people (offices, living rooms, industrial areas), since extraneous noise leads to false reactions of the devices.

The most common place to install a slam light switch is the bedroom. It is very convenient to control the lighting without getting out of bed. Cotton systems are popular in families with small children, since to turn the light on or off you no longer need to reach for a high-mounted switch.

Many people confuse cotton and acoustic devices. The acoustic switch is triggered by any noise, and the clap switch is triggered only by claps.

Principle of operation

The device operates using a microcontroller installed in it. The controller authorizes turning the light on and off by clapping. If desired, this device can be used to control other electrical household devices (air conditioners, fans, etc.).

A typical audible light switch contains an electronic microphone with a preamplifier. This component amplifies the sound entering the device, which allows you to record even the quietest pops. The operation of the amplifier is controlled using transistors VT1 and VT2. The circuit is controlled by a pair of resistors R2, and diodes VD1 and VD2 are used to equalize the signal.

The sound from the clap passes through the microphone, where the electrical impulse is amplified and transformed. Next, the sound is equalized due to the work of rectifying diodes. The sound is controlled by a resistor (if the sound volume level is below the specified level, the resistor will prevent the device from operating). When the signal on the capacitor is leveled, the voltage increases and the transistor switch VT3 opens.

The light turns off and on after sequential charging and discharging of the capacitors. At the end of a full cycle of activity (one more bang), the resistor and capacitor C10 are discharged in four seconds. This causes the device to turn off.

Specifications

As an example, let’s look at the characteristics of a standard device for turning the light on and off by clapping.

Device details:

1. Power is supplied from a standard network with a voltage of 220 Volts.
2. The maximum total power of consumers does not exceed 300 Watts.
3. Sound control ranges from 30 to 150 decibels.
4. Permissible temperature range: from 20 degrees below zero to 40 degrees above zero.
5. Housing protection class - IP30.

A variety of lamps are used in the network:

1. Incandescent and halogen light sources.
2. Energy saving or fluorescent light bulbs.
3. LED devices.

The specified characteristics comply with legal requirements Russian Federation under number 261. This act regulates the rules for the rational use of electrical energy.

The size of the equipment is similar to a matchbox, that is, compact. This makes it possible to install it close to the lamps. The device is fixed using self-tapping screws or double-sided tape.

Connection diagram and installation

Below is a diagram of a clap light switch. Based on it, you can connect this device.

The white conductors available on the device are connected to the network. The load is connected to the black wires. To connect copper conductors, you will need terminals. The black conductors are connected to the lamp bulb. These devices are connected in parallel.

The switch is powered via a single-key switch. If you need to turn it off, you just need to press the switch.

The sound sensitivity is controlled by the corresponding regulator. It is recommended to use the average audio value.

Tests

Before turning on the device, you should configure it to prevent false alarms. extraneous sounds. For example, a cotton device should not respond to the blows of a hammer, the knocking of dishes, a ringing telephone, or a switched-on hammer drill.

Settings are made experimentally. The device is considered configured when it responds only to claps.

Manufacturers

The most famous models presented on Russian market- “Ecolight” and “Claps”. Let's look at their main characteristics.

Ecolight switch

The Ecosvet device is designed to work with 220 Volt light bulbs.

Main parameters of the device:

sound signal spread - from 30 to 150 decibels;

housing protection level - IP30;

permissible temperature range - from 20 degrees below zero to 40 degrees above zero;

cost - from 350 rubles.

“Ekosvet” is fixed with self-tapping screws using the mounting feet. It is not recommended to install the device in noisy rooms. Despite the fact that “Ecosvet” is configured to clap, false alarms are possible.

The figure above shows the connection diagram of the device. "Ecolight" is connected to a conventional switch to provide the ability to de-energize the circuit and stop its operation.

"Claps" switch

This model is one of the latest developments, where the audio signal is processed by an advanced microprocessor. The device only responds to claps, so it ignores false information. A prerequisite for operation is a certain nature of sound transmission, when the claps must occur in a row.

There may be one or more switches in one room. Each of them will be set to a given number of claps. To do this, place a jumper on the board in the desired position. As a result, it becomes possible to control several devices that are unrelated to each other, for example, an air conditioner and a lamp, a TV and a tape recorder. “Claps” is compact (about the size of a box of matches) and can be mounted anywhere, including in a socket box.

“Claps” costs more than “Ekosvet” (2450 rubles versus 350), but its reliability is higher. “Claps” will work with fluorescent light bulbs even when the load is switched on smoothly (“Ekosvet” is not capable of this).

Making a switch yourself

You can make a cotton device yourself.

To do this you will need 3 boards:

• Arduino Nano;
• sound module;
• power relay board.

In addition, you need a computer, a USB cable, and a 5-volt power supply. You should install the Arduino IDE program on your computer, designed for flashing the microcontroller firmware.

After copying the sketch data and pasting the text into the Arduino IDE window, you must immediately flash the controller firmware. When changing some settings and overwriting the device, it is possible fine tuning sound relay for your own needs.

The diagram shows that the controller has 4 wires. A couple of them go to power, the yellow wire is directed to control the power relay (pin 13), and the green wire is the control wire from the microphone connected to the A0 controller.

Note! A condenser-type microphone can be replaced by an electret microphone, in which a fixed condenser plate and source DC voltage an electret plate is used. A distinctive property of the material is the ability to maintain a surface charge over long periods of time.

The chip contains 8 analog inputs and 14 digital inputs and outputs. In this example, A0 and D13 are used, since they turn on the LED on Arduino board.

When replacing the AnalogRead indicator, the threshold sensitivity is determined. The highest value is 1024. If you change the Delay value, the time it takes to execute the sketch will be adjusted. In this way, the desired switching readiness time is achieved. A threshold is also determined that protects against interference and false alarms. The sensitivity of the microphone can also be changed using a variable control located on the board. Setting up and testing the circuits is carried out on the Arduino UNO board.

It is powered by a DC source, voltage from 5 to 12 volts. The parts are available and inexpensive; they can be purchased at any radio store. Personally, I used parts that I soldered from old boards. The circuit is really simple, and even if you have little knowledge of radio electronics, using this article as a guide, you can assemble this device.)

Initially, I found this circuit without any description and naturally there was no printed circuit board, so I had to make it myself in order to make the assembly process easier for myself and of course for you, so use it. Download PCB

Acoustic switch circuit:

The circuit consists of microphone amplifier, which is assembled on two KT315 transistors and a power section on a KT3107 transistor (BC557). To increase microphone sensitivity, you can use more powerful transistors, for example KT368 and the like. In the power department it is also sufficient wide choose analogues, almost any transistor PNP structure will do, for example KT814 or KT818, here you need to first look at the power of the power source used.

Below are photos of the necessary parts:

Acoustic switch parts list:

So, first you need to make a printed circuit board. Please note that the printed circuit board has holes for the VD1 diode, since I plan to control room lighting and will use a 12 volt relay as a load. The diode is needed to protect transistor VT3 from the EMF of the relay coil. If you are going to connect a light load to the switch, you can replace it with a jumper.

After making the board, drill holes and tin it. Open the signet in the sprint-layout 6.0 program and looking at the locations of the parts, solder them in place.

Our acoustic switch is ready! Now I want to tell you about a small nuance, the circuit uses a 1.5 kOhm resistor R8, I replaced it and set it to 2 Ohms, since the voltage at the load output dropped significantly and the relay did not work. If you have the same problem, then follow this advice. That's all, share the article below if you liked it.

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Buy an acoustic switch, kit for self-assembly:

The acoustic switch is quite entertaining and interesting device, which is very useful to assemble for a novice electronics engineer or radio amateur to improve their skills. Let's look at how to make an acoustic switch with your own hands from available radio elements.

The principle of operation of such a device is that a sound signal, usually a clap of the hands, is perceived by a microphone, after which the load is connected or disconnected using various circuit solutions. Most often, the load is an incandescent lamp or an LED lamp.

How does an acoustic switch work?

The operating algorithm of the simplest acoustic switch looks like this: when a clap is heard, the lamp turns on, with the next clap it goes out, and this repeats all the time. In this case, the light bulb can remain in any state indefinitely. We will assemble a more advanced device.

The first operating algorithm of our acoustic switch functions in this way: one clap - one lamp lights up, the second - the second, the third - the third, the fourth - all the lamps go out. Then everything will happen again.

The second algorithm - everything happens in the reverse order: the first clap - three lamps turn on, the second - one goes out and two lamps remain on, the third - one lamp remains on, the fourth - all the lamps turn off. This option is well suited for a “night light”, since with each clap the light becomes dimmer and then goes out.

Acoustic switch circuit

There are a huge variety of acoustic switch (AS) circuits: on transistors, logic chips, flip-flops, etc., but we will assemble our device on a microcontroller. Using a microcontroller, you can quite simply implement algorithms of varying complexity with minimal circuit modification or no modification at all.

The first and integral element of any acoustic switch is a microphone. The microphone converts the audio frequency signal into alternating voltage. The simplest electret microphone will suit us.

One terminal of the microphone is connected to the negative, and the second, through trimming resistor R1, with a resistance of 510 kOhm, to the positive. Using R1, you adjust the microphone sensitivity. Next, the alternating signal from the microphone output through the isolation capacitor C1, with a capacity of 1 μF, is supplied to the device, made on a single transistor BC547. The emitter of the transistor is connected to the minus, and the collector is connected to the plus through resistor R2, with a resistance of 1 kOhm. The amplifier is adjusted using a tuning resistor R3 with a resistance of 1 MOhm.

Next, the amplified signal is fed to the input. Depending on the number of received pulses, which corresponds to the number of claps, the microcontroller outputs a high or low potential to the corresponding pins. In this circuit, we use three pins of the MK microcontroller, which operate as output. They feed three similar circuits. Let's consider the operation of one circuit.

When there is a high potential (+5 V) at the MK output, transistor VT2 of the 2N2222 series, connected to the MK by resistor R4 (1 kOhm), opens and relay coil K1 receives power. When relay K1 is triggered, its contacts close in the lamp power circuit and thus it lights up.

The relay coil K1 should be shunted with a reverse diode VD1 to protect against overvoltage, since the coil has some inductance, and if the circuit breaks, a voltage surge may occur, although not significant in this case, but it is better to be safe. Almost any diode with a current of at least 100 mA will do; you can use 1N4148.

Any relay can be used, but you should focus on the following parameters: supply voltage 5 V, voltage of the closing contacts - alternating, 230 V. The contact current is determined by the load of the circuit that the contacts will close and open. I used the following type of relay: HW32-005VDC-A. If you find a relay with a coil supply current of no more than 20 mA, then you can do without a transistor switch.

The acoustic switch circuit is powered from a stabilized power source with a voltage of 5 V. You can take any ready block food or collect it yourself, as described in.

Setting the acoustic switch

The device is configured using two variable resistors. I achieved such sensitivity that the switch did not respond to music, speech and light door knocks, but at the same time it worked perfectly when there was a clap from the opposite end of the room. Please note that the microphone must be positioned in the direction of the clap.

You've probably wondered why cotton? The fact is that the amplitude of the sound wave caused by clapping is much greater than during a normal conversation or music, so the amplifier can be configured in such a way as to filter out other sound sources, thereby eliminating false triggering of the device.

Now, I hope you are convinced that making an acoustic switch with your own hands is quite simple. This device I assembled it on a breadboard, but if you use SMD components and solid-state relays, the size of the acoustic switch will not exceed a matchbox. Happy assembly everyone!

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