DIY cotton light switch. Acoustic switches. Device and operation. Application. Is it possible to make a switch with your own hands?
Sound relay and circuits for turning on the lighting by calling a mobile phone. (10+)
Automatic lighting control - Mobile control. Sound control
Sometimes it is useful to be able to turn on the lighting with a call from your mobile phone. For example, in order to get home at night, I need to turn on the spotlight that illuminates the road. The switch, of course, is at home.
I immediately decided that I would not open the mobile phone and solder it inside. Firstly, it is illegal. Independent modifications to devices subject to mandatory certification are not permitted by law. Secondly, there is no need for such re-soldering.
As with previous devices, I chose the transformerless power supply option. This immediately necessitated galvanic isolation from the telephone. For safety reasons, the mobile phone should not be directly connected to the lighting network. I settled on three circuit options: acoustic, optical and transformer isolation. All three schemes respond to a call on a mobile phone. Since the connection is not established, no money is debited, so the function is completely free if you select a tariff without a subscription fee for the phone in the management system. After the call, the lighting is turned on for a fixed time. After which it goes out, but you can turn it on by calling again.
Unfortunately, errors are periodically found in articles; they are corrected, articles are supplemented, developed, and new ones are prepared.
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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 of a 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.
To make it easier to study the circuit, we have highlighted the main components on it: a microphone amplifier on the KT3102 transistor, a comparator on the ne555 chip, a TM561 trigger and a KT3102 transistor, which controls the power relay.
No less interesting will be the self-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 an Arduino UNO board 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!
Also read:
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 in order 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.
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 a microphone amplifier, which is assembled on two KT315 transistors and a power section on a KT3107 (BC557) transistor. To increase the sensitivity of the microphone, you can use more powerful transistors, for example KT368 and the like. In the power part, there is also a sufficiently wide selection of analogues; almost any PNP structure transistors are suitable, for example KT814 or KT818, here you first need to 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:
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The acoustic switch Entrance lights can be installed on the landing in the entrance. It responds to a sound signal, such as clap. If this acoustic signal is sufficient to trigger it, then it turns on the lighting for one minute, which is more than enough to open the door of your apartment.
Most acoustic circuits switches The lights have one significant drawback - cycling, as a result of which the acoustic switch circuit is unstable. One of the reasons for this is the thyristor, which causes distortion of the sine wave in the network; as a result, noise through the power circuit reaches the microphone amplifier, thereby causing cycling.
The most effective option to prevent the circuit from looping is to automatically turn off the microphone after turning on the lights, and connect it back a couple of seconds after turning off the lights.
Operating principle of an acoustic switch circuit
Scheme The sound sensor consists of an electret microphone with its own, a resistor for adjusting the sensitivity R2, assembled on two transistors VT1 and VT2 of a two-stage audio amplifier, a detector on diodes VD1 and VD2 and a control switch on transistor VT3. After the clap, the alternating voltage from the microphone output, passing through the amplifier, is rectified by the diode detector and acquires a certain constant value.
After the clap, the sound exceeds a certain level, which is set by variable resistor R2, the voltage on capacitor C8 increases, and opens the transistor switch VT3. A log appears on the VT3 collector. 0 corresponding to the level of CMOS chips. A time delay circuit is assembled on the elements of the K561LE5 microcircuit, which turns on the lighting for a minute and turns off the sensor node.
In the initial state, when the light is not turned on, a log goes through resistor R12 to element DD1.4. level equal to 1 CMOS. Accordingly, the output of DD1.4 will be a log. 0. Capacitor C10 will be discharged and input 9 of DD1.3 will be log. 0, and at pin 8 of DD1.3 due to resistor R8 there will be logic 1. After the clap, transistor VT3 will open, which will lead to the appearance of a log. 0 at pin 8 of DD1.3. Because of this, the log. 1 appearing on pin 10 of DD1.3 puts the trigger assembled on elements DD1.1 and DD1.2 into a single state. A unit from the trigger output turns on the relay through transistor VT4, and thereby turns on the light.
At this very moment, due to the VD4 diode, the level at the DD1.4 input drops to almost zero. As a result, capacitor C10 is instantly charged, as a result of which element DD1.3 closes, which leads to ignoring signals from the sensor node coming to pin 8 of DD1.3, thereby protecting acoustic switch from looping.
In parallel, capacitor C9 is slowly charged through resistor R9 (this takes about one minute). After charging the capacitor, the trigger will go into the opposite state, that is, now its output will be a log. 0, which will turn off the light. Due to the VD4 diode, the inputs of D1.4 will again be log. 1. Then, through resistor R11, capacitor C10 will discharge within 3 seconds, and the acoustic switch will go to its original state, ready to turn on when a new one appears cotton.
Acoustic switch circuit details
The power supply for the acoustic switch is transformerless; excess mains voltage is extinguished by capacitor C12 (its reactance). Afterwards, the alternating voltage is rectified by a diode bridge on VD7-VD10 and stabilized around 12 volts by means of a zener diode VD6. Any transistors or . can be changed to KT503 or . Capacitor C11 must have a voltage of more than 12V, and capacitor C12 must have a voltage of at least 400V. Rectifier diodes VD7-VD10 are any rectifier, in particular they can be KD209.
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