Acoustic switches. Device and operation. Application. Acoustic switch: how to make a simple and reliable cotton switch How to make a simple sound light switch
Content:Many modern lighting systems are equipped with remote control. For this purpose, remote controls are used, as well as signal-type equipment, for example, a clapper switch. In this case, the push to turn it on and off is a sound of sufficient intensity, approximately equal in strength to clapping your hands. Previously, the assembly of such circuits was carried out exclusively by radio amateurs. Currently, audio devices can be purchased freely at most electrical stores.
Cotton light switch
In order to activate such a switch, you just need to clap your hands. As a result, the device will turn on or off. Typically, these devices are installed in rooms with minimal noise levels - in bedrooms, utility rooms, storage rooms, basements, etc. It is not recommended to use cotton switches in noisy places with a lot of people, as excessive noise can reduce the quality of the device. Offices, production sites and workshops are completely unsuitable for installation.
These devices are often confused with acoustic switches. The main difference between them is that the acoustic device is triggered by any noise, and the clap switch is triggered by clap. These devices have proven themselves well in families with small children who cannot reach a regular switch. Now the child just needs to clap his hands to turn the light on or off.
Cotton switch circuit
All clapper switches are installed according to a standard pattern, similar to single or. Some models may have their own individual characteristics, but the general principles remain the same. That is, a single-key device is connected to the network in such a way that it can power the cotton device.
The switch and lamp operate according to the standard scheme. First, through the shield and distribution box, you need to supply power to a regular switch. The neutral wire from the panel is connected to one lamp or group of lamps. The lamps themselves are connected in parallel with the disconnecting device.
The power circuit going to the key switch must be interrupted and connected to the acoustic device. This operation is very simple due to the small size of the device, allowing installation directly on the lamp body. Therefore, there is no need to install additional grooves in the wall.
Each standard switch is equipped with two pairs of wires - white and black. The white wires are connected to the power supply, that is, to the phase and neutral cables from the panel, and the black wires are connected to the load. It is recommended to connect the conductors using conventional twisting or using terminals. In this case, soldering of joints is not used.
Once the connection is complete, the standard key switch is turned on and the operation of the entire system is checked. If necessary, it can be completely removed from the circuit and the power connected directly to the cotton device. All that remains is to configure the device in such a way as to eliminate false alarms from extraneous sounds.
DIY cotton switch
All acoustic or cotton systems have a microphone, which is used to record sound. In addition, the circuit is supplemented with a time relay or a control power relay. In a standard circuit operating with a voltage of 220 V, the signal coming from the microphone is amplified by transistor T1. Next it passes to the resistance matching unit and the emitter follower of transistor T2. A digital chip is used to assemble the trigger and signal comparator.
The main function of the comparator is to protect the switch from acoustic interference, cutting off long or too short sounds. When the signal passes, the trigger state changes to on or off. Thus, the trigger controls the lighting device through a thyristor and a power transistor. A similar circuit can be assembled based on an integrated timer.
Drawing up a diagram will be more convenient if you highlight certain zones on it. They include a transistor microphone amplifier, a comparator on a microcircuit, a trigger, and a transistor that controls a power relay.
You can assemble a clap switch yourself using an Arduino microcontroller. To do this, you will need a sound module board, a power relay and an Arduino Nano. In addition, you will need a computer, a USB cable and a 5-volt power supply. To flash the microcontroller firmware, the Arduino program is installed on the computer.
By changing some of the adjustment parameters of the sound relay, you can fine-tune it. Wiring is connected in the same way as in standard circuits. All that remains is to set the protective threshold against false alarms and interference, and the device is ready for operation.
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 such electrical circuits were assembled by radio amateurs, now the device can be bought 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. An electret microphone is common. 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 a low-power LED lamp, 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 a sound signal is received 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. It is then amplified by bipolar transistors and 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 amplified, passing through the operational amplifier (DA1.1), charging 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:
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 can be seen that it is connected to a regular switch, which is needed to de-energize the circuit and put 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, a 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 to the previous model, the price of the device is significantly higher (RUB 2,450).
If the cotton switch provides for smooth switching of the load, then it will not work with fluorescent lamps. 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.
The figure shows a diagram of an acoustic relay I made. This diagram has never been published anywhere before. A special design feature is the use of a carbon microphone. These microphones are used in telephone sets, in which there are no amplifiers for transmission and reception (TA-68, TAN-70, TAI-43 and others). The amplitude of the electrical vibrations of the microphone is sufficient for communication over tens of kilometers without the use of amplifiers. In addition, it has incredible sensitivity. The disadvantage is the narrow bandwidth of the audio frequency spectrum. But in our case, this is a plus, since unnecessary sounds and interference are cut off.Operation of the circuit. When you clap your hands or click, the carbon powder in the microphone moves and changes its resistance. In this case, at the connection point between the limiting resistor R1 and the microphone, an alternating component appears, which, through the separating capacitor C 1, is supplied to the base of transistor T 1. Transistor T1 is both an amplifier of alternating and direct voltage. With the help of resistor R2, transistor T1 is in a slightly open state. The variable component received at the base is amplified by a transistor and, from the collector through capacitor C2, goes to a doubler rectifier assembled on elements DD1, DD2, C3. Double the constant voltage accumulates on capacitor C3, which is discharged through the circuit: minus the capacitor, resistor R1, base-emitter T1, plus the capacitor. In this case, the transistor opens like an avalanche, relay P1 is activated, its contacts close for the duration of the sound signal. When setting up the operation of the circuit, sometimes it turns out that its sensitivity is too high; it is triggered by cars passing along the street or by waving a hand near the microphone. It all depends on the type of relay used. You can roughen the circuit by connecting a variable resistor in series with capacitor C1. In order to switch the load (light bulbs) using claps, it is necessary to add a trigger to the circuit. The circuit of such a trigger on a polarized relay is shown in Figure 2 - it has not been printed anywhere before.
When a sound signal is given (clap, click), the contacts of relay KP1 are temporarily closed. An alternating voltage of 220 V through the lamp L1, diode D1 with a positive half-cycle is applied to the end of the second winding of the RP-4 relay, pin 8, the beginning of the winding, pin 7, current limiter resistor R1, capacitor C1, closed contacts of the relay KR1, pin 220V. The charging current of capacitor C1 switches the relay armature to the left position according to the diagram, light bulb L1 lights up and light bulb L2 goes out, diode D1 is blocked by the relay contacts, and diode D2 is unlocked and ready for operation. When the next sound signal arrives, the contacts of relay P1 KP1 close. A voltage of 220 V through light bulb L2 and diode D2 is applied as a plus to the beginning of the first winding, contact 5, from the output of the winding, contact 6 goes to resistor R1 and recharges capacitor C1. A polarized relay switches the armature to the right contact in the circuit. Diode D2 is blocked, and diode D1 is ready for the next cycle. Light L1 goes out and light L2 lights up. Thus, upon admission sound signals alternate load switching occurs. In order for the trigger to perform the function of turning on and off only one light bulb, you need to exclude one of the light bulbs from the circuit, and instead turn on a series chain of a 0.33 μF x 300 V capacitor and a 5–10 kOhm, 2 W resistor. When setting up the operation of the trigger, it is necessary to adjust the armature of the polarized relay so that it switches well and is securely fixed in the right or left position.
Correctly determine the beginning and end of the relay windings or change the polarity of one of the diodes. Of course, this design of an acoustic relay on a carbon microphone is more suitable for beginners, so in the next article it will be described on one microcircuit, and a piezoelectric element is used as a sensor.
Discuss the article SIMPLE ACOUSTIC RELAY
An acoustic switch is a very useful and necessary thing in the household, especially if you want to automate some devices or lighting in your home and add creativity to your home! Using an acoustic switch, you can turn the lighting off and on or use it for other devices, such as an electric kettle or fan.
This scheme is fully operational, streamlined and stable. There are many diagrams of similar devices on the Internet, but when assembling them, a lot of performance problems arise and some of them lead to long discussions at the end of which, the problem is often not solved. Below is the diagram itself.
The circuit is powered by a voltage of 5 to 9 volts, so choosing a power source will not be difficult. You can use, for example, a crown or other batteries and accumulators. If you need stationary power, then there are many power supply circuits online, even a transformerless one will do.
The printed circuit board is made for DIP components, but despite this, it has quite compact dimensions and choosing a housing for it will not be difficult. You can download the printed circuit board from the link:
(downloads: 726)
List of parts for assembly
PCB manufacturing
I will not explain in detail how to make a printed circuit board, as it will take a lot of time. The PCB file is opened using the sprint-layout 6.0 program:
(downloads: 612)
The circuit uses diode VD1; it is needed to protect transistor VT3 from the EMF of the relay coil. If you connect a relay as a load, then you need to install a diode; if you use a light load, then you can install a jumper instead.
After making the board, to avoid oxidation, tin the thresholds with tin. Open the sprint-layout 6.0 program and solder all the parts on it according to the location. If everything is done correctly, the parts and values are not mixed up, then the device should work immediately without any problems.
This is what the assembled acoustic switch looks like.
And another photo with a connected battery and an LED on the load.
I would like to tell you about one problem that may arise. The circuit contains a 1.5 kOhm resistor R8, if you use an LED as a load, you can leave it, if you plan to install a relay, then replace the resistor with a 2 Ohm. There shouldn't be any more problems))
The result was an inexpensive but very effective and useful device that will definitely find its use in the household!))
To increase their comfort and simplify their daily routine, people are constantly coming up with new devices. Today we will look at a device for remote control payload, using claps. A homemade cotton switch is useful, for example, for turning on the light in a vestibule or pantry, where usually finding the right switch causes a lot of inconvenience. For readers of the site, we will tell you in detail how to make such a device with your own hands, what parts need to be prepared for this, and what assembly scheme should be followed.
Assembly diagrams
All cotton or acoustic machines are united by the presence in the circuit of a microphone, which is needed to record sound. The design also provides an amplifier, trigger or to control the power switch.
In this circuit, operating from a 220V network, the signal from the electret microphone is supplied to transistor VT1 for amplification, then to the resistance matching unit and the emitter follower on transistor VT2. And then to the comparator and trigger, assembled on the K561TM2 digital chip.
A comparator is necessary to protect the switch from acoustic interference; it cuts off sounds that are too short or long. The signal that passes through the filter changes the state of the trigger (on or off), which in turn controls the load through a power transistor, relay and thyristor. It can be any lamp, for example an incandescent one.
Here is a diagram for assembling a homemade cotton switch with a similar purpose - on an integrated timer.
For the convenience of studying the circuit, we have highlighted the main components on it: a microphone amplifier on a KT3102 transistor, a comparator on a ne555 chip, a TM561 trigger and a KT3102 transistor, which controls the power relay.
No less interesting will be the independent assembly of an acoustic relay on an Arduino microcontroller and ready-made modules for it, which will significantly simplify the understanding of the principles of operation for beginners and will allow you to fine-tune some operating parameters.
To make a cotton machine with your own hands, you need to prepare three boards:
- Arduino Nano;
- sound module;
- power relay module (note that it is 5 volts).
You also need a computer to download the firmware, a USB cable, and a 5-volt power supply (any phone charger will do). You need to install the Arduino IDE program on your PC to flash the microcontroller firmware. You can download it for free from the official website of the board developer.
By copying the text of the sketch (program) and pasting it into the Arduino IDE window, you can immediately flash the controller. By changing some parameters and rewriting the device, you can fine-tune your homemade sound relay for stable operation. As we can see from the diagram, four wires are connected to the controller: two for power. The yellow wire connected to pin 13 is for controlling the power relay. The control wire from the microphone module connected to the analog input A0 of the controller is marked in green.
The chip contains 8 analog inputs and 14 digital input/output contacts. For our project, we took A0 and D13, since together with it the LED on the Arduino board lights up, and you can clearly see when a signal is sent to the relay module.
Arduino sketch for making a sound relay:
By changing the x value in the if(analogRead(Al)>x) line, we set the sensitivity threshold, the maximum value of which is 1024. By making changes to the delay line, the delay period after the sketch is executed changes. This sets the readiness time for switching. In addition, the protective threshold against interference and false alarms is adjusted. In addition, the sensitivity of the microphone can be adjusted with a variable resistor on the board using a small screwdriver.
To test and configure the circuit, we took a board Arduino UNO, based on the ATmega238 microcontroller. In this case, any other models are also suitable, since we do not use many board pins, and the sketch does not require high performance.
The video below clearly shows a homemade cotton switch, which we assembled according to the diagram provided:
Video instructions
Several simple ideas for making your own acoustic light switch are shown in the video:
Now you know how to make a cotton switch with your own hands. We hope that the provided assembly options, simple diagrams and video tutorials were useful and interesting for you!
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