We make a bell for the front door from a mobile phone “dialer”

I present to your attention a doorbell circuit that was assembled many years ago and has been in use for the same amount of time. It would be more correct to call this device: “Waste into income!” Because what it was made from was literally lying underfoot. This was during Soviet times. I was working at a small automatic telephone exchange at the time and had a lot of free time that I wanted to convert into money. Then he began to collect electronic calls based on this scheme and insert them into rotary telephones. The installer of the city automatic telephone exchange willingly helped me with the implementation, making his own profit from it. The device imitates the sound of a bouncing ball. All characteristics are adjusted by selecting the capacitance of the capacitors and adjusting the variable resistor.

Electrical circuit diagram

Once assembled without errors, it starts working immediately. Power supply is possible from a 12 volt DC source (then diodes D1-D4 and capacitor C4 are excluded). The ringing pulses of an alternating current telephone exchange are 110 volts 25 hertz - in this case, the capacitance of capacitor C4 should be 1 microfarad per 400 volts.

AC voltage 220 volts 50 hertz, when used as an apartment bell (in this case, the capacitance of capacitor C4 should be 0.5 microfarads at 400 volts). The device was assembled using pieces of foil getinax, which were cut on a machine (Skillful hands) with a small circular cutter. I used one board as a conductor for drilling holes, but it can also be assembled using wall-mounted installation.

Scheme of a touch doorbell on a microcircuit

Transformer T1 is the output transformer from a small transistor radio. Dynamic head BA1 with a power of 0.05-0.5 W with a voice coil with a resistance of 4-50 Ohms.

The power source is a Krona, Corundum battery or two 3336 batteries connected in series. The sensor element can be made from foil PCB. The distance between the contact pads should be 1.5. 2 mm, and the gap between them is protected from dirt and moisture with varnish or paint. The shape of the contacts of the sensor element can be any.

Setting up a call comes down to selecting capacitor C1 to obtain the required tone of the sound signal for a specific design of the sensor element.

Rice. 1. Scheme of a touch-sensitive doorbell (a) and its circuit board (b)

I.A. Nechaev. Mass Radio Library, Issue No. 1172, 1992.

Parts used

Transistor T1 - mp25-26, T2 - kt605 or p307-309, but p605 works better, diodes D1-D4 - D226, but others are possible, although D226 gave better results. Capacitors C1-0.1 C2-0.05, trimming resistor - 47k, C3 - 100 microfarads per 100 volts. The telephone capsule was used as an emitter, but only very old ones (large diameter).

The use of a Czech capsule with a resistance of 50 ohms gave very good results, but it has one feature - to achieve good volume, you need to remove the plastic plug from the side of the contact screws, under which there is an adjustment screw and, having turned on the device, use a small screwdriver to make adjustments, unscrewing and tightening screw to achieve maximum sound volume.

Warning! If you are going to use this device as a doorbell, do not set it up by connecting it to a 220 volt network! You may be exposed to high voltage! Set it up by connecting 12 volts to DC, and then connect the mains voltage.

After the doorbell gave up its life, I dug up an old telephone on the mezzanine, tore out this electronic bell from it, packed it in a box of cotton swabs, and now it continued its service above the door. The author of the project is Wolf9405 .

Discuss the article DOORBELL FOR BEGINNERS

A high-quality wireless bell for the front door of an apartment or house is in no way inferior to its wired counterpart, and even surpasses it in ease of installation and dismantling. The signal transmission unit can be so miniature that outwardly wireless call models are no different from regular ones. They are equipped with a video peephole combined with a motion sensor, backlight, anti-vandal cover and other little things to increase the comfort of use.

DIY electromechanical doorbell

An old telephone with a dialer is suitable as a starting material for making such a device. You can find it in the closet among unnecessary things.

The main interest is the electromagnetic ringer of this phone. After removing it, you should assemble a connection diagram with a step-down transformer. The best option for operating an electromagnetic bell would be its windings with a voltage transfer ratio of 220 V/30 V. A push switch is placed to close the primary winding of 220 V, rather than a locking one, to ensure intermittent operation of the device. Visually, the diagram of an electromechanical bell based on parts of an old telephone looks like this:

Key Features of Wireless Calling Models

When choosing any item, first of all it is worth assessing how suitable it will be for the conditions in which it will be used. To accurately understand whether it is worth installing a wireless call at home, you need to evaluate their features in more detail:

• There is no need to run wires from the button to the speaker. This is the main difference, often influencing the choice of this type of device for a private home, in which the front door is quite far from the gate and a friendly dog ​​runs between them.

Here you can install a regular wired bell without any problems, but it is best to bury the wire underground. Otherwise, it may stand out somewhat in the yard design.

• Autonomous power supply. Since wireless calls are battery-powered, when the lights go out, guests will not have to call the host from the street for a long time. This is also a determining factor for summer cottages that do not have electricity. Powered by batteries at the same time creates certain inconveniences associated with their periodic replacement, but here you have to choose what is more important.
• A wireless call cannot be installed everywhere. It is necessary to look at the distance from the receiver to the transmitter and the presence of obstacles between them that impede the passage of the radio signal.
• If the house has more than one door (or gate), but several, then you can purchase an electric bell with two buttons. This will significantly reduce the cost of their installation compared to wired models.

• Easy installation, dismantling and transfer of the button. This feature is rarely in demand, but if you need to move the gate, change the side it opens, or install a mailbox exactly where the button is located, then it will be much easier to do this. If with a standard call you inevitably have to re-wire the wiring, then the wireless one is simply re-wired.

This may also be one of the disadvantages - some manufacturers make bell buttons with Velcro, which, if done poorly, can quickly fall off. If you are buying just such a bell, then you need to evaluate whether it is worth additionally screwing it on.

Making a choice

Key points to pay attention to when choosing:

1. Call type. When choosing a device for a private home, this factor is very important. That is, it is best to give preference to modern models that have the ability to make a recording, save it for the required period, as well as other additional functions.
2. The principle of signal transmission from the gate to the house: wired or wireless. The fact is that nowadays technology is rapidly developing, and therefore wireless models, which are more convenient to use, are increasingly being installed in the private sector.
3. Nutrition. It can be produced directly from the network, from a battery or batteries. But it should be remembered that a device that operates from the network has a greater ringing power, but in the absence of electrical energy it will not work.
4. External indicators. For a bell, the appearance is quite important, since it must be harmoniously combined with the entire design of the house.
5. Additional functions. If you install, for example, a home bell with video, you can not only find out that someone is standing outside the door, see him, but also communicate without opening the door.

Power supply circuit for components

A street bell nowadays has a rather complex design, and therefore, in addition to a simple notification of arrival, you can use a lot of other auxiliary functions.

Scheme and principle of operation of wireless calls

For the average user, the principle of operation of wireless calls is very simple - the transmitter button is pressed, the radio signal from it goes to the receiver, where it activates an electrical circuit that supplies voltage to the speakers and a melody plays.

Despite the fact that the device diagram is rarely attached to it by the manufacturer, numerous radio amateurs have adopted the remote method of controlling the device itself, making not only bells with their own hands, but also various control devices - a wireless light switch or a remote garage door lifter.

The circuits of these devices are easy to manufacture and unpretentious in operation. The first two are separate boards for the button and the receiver, and the third circuit does not even require any configuration - the receiver is a regular supergenerator and, according to user reviews, everything is highly stable.

Types of residential calls

There are two types of electric residential bells based on the connection method - wired and wireless. Wired ones are connected to a 220 V network, there are models that operate on a reduced voltage of 12 V. They are called wired because the bell button and the indoor unit must be connected by wires.

Wired calls - the button and the internal unit must be connected by wires

In wireless electric calls, the button and the internal unit are not physically connected. They contain a miniature transmitter (in the button) and a receiver (in the indoor unit). They communicate with each other at some frequency. There are two types of wireless call power:

• The indoor unit and button are battery operated.
• The button is powered by batteries, the internal unit is powered by a 220 V network. Moreover, there are two ways to implement internal units: with a standard connection to the terminals by wires and with installation in a socket. In the latter version, there is a regular electrical plug on the body. In this case, connecting a bell in an apartment or house is very simple: you need to install the indoor unit into a socket, screw the button on the entrance/gate and insert the battery.

Wireless calls by connecting the indoor unit via a socket

As already mentioned, in the wireless version, the button and the electric bell “communicate” with each other through signals. Signals can be transmitted in analog or digital form. More reliable signal transmission in digital format - less susceptible to distortion. In addition, such models have the ability to change the channel through which reception/transmission occurs. This is not possible when transmitting an analog signal. Why is this bad? Call range is 100 m or more. And if there is some device in this area that operates on the same frequency (bell or other), your receiver can pick up its signals. In this case, false positives occur.

There are also doorbells that separate apartment and street doorbells. They differ in that for those installed outdoors, the buttons are sealed and dustproof. In addition, it is recommended to install them under a small canopy - there will be fewer problems.

This is interesting: Cable under a concrete path: let's look at it in detail

Video eye for wireless calling

The general scheme of installing a bell on a door can allow you to remotely monitor an entrance or street. If a video peephole with a camera is installed on the front door or gate, then inside the house you can immediately see who is calling. Depending on the device model, the image transmitted by the video eye is displayed on a separate receiving display or transmitted to an ordinary computer monitor. The quality of the picture is determined by the camera installed in the video peephole.

Read also: Image of a threaded connection in the drawing

When choosing such a device scheme, it must be taken into account that the video eye with the camera requires a more thorough power supply. The main solutions to this problem are as follows:

• Choosing a high-quality kit with minimal power consumption (if you need to record constantly).
• The scheme provides for using the camera only after pressing the call button (the video eye records only those who called).
• The video peephole and camera are powered separately from the network. It would seem, why would there be a wireless call, but this scheme also occurs quite often.

• The connection diagram should be equipped with a motion sensor (the video peephole and camera start working when someone passes by - useful if there are people with an inadequate sense of humor in the entrance).

Depending on why you plan to install a video peephole with a camera, the resolution of the latter is selected - what quality it will take a picture. It should also be taken into account that the higher the resolution, the more data will be transmitted by the camera via a radio channel per unit of time and the more demanding such a circuit is in terms of power supply.

Yellow and wireless, standalone call.

Some of the owners of private and non-private homes use wireless calls. They are produced as a set in two versions: a remote button transmitter with its own battery power is equipped with either a mains-powered or battery-powered receiver. Both options have their advantages and features, and therefore I invite you to see with me what happens if you combine a bell, uninterruptible power supply, a motion sensor and backlight. Over the course of three years, I changed two models, the last one being this battery-powered one.

The mains-powered model does not require batteries, just a free 220v outlet. Let's say that the fact of a power outage in the apartment is not significant - the caller often duplicates pressing the button with a knock on the door. But in a private house, I periodically managed to let in crows - several visits, the water utility workers called to nowhere. I suspect that there was a knock on the gate, but my suspicions (if I was in the back room at that time) remain so. In general, after a year and a half, the mains-powered receiver failed when the capacitor power supply built into the receiver failed. The battery-powered model is not tied to a power outlet - after all, you can take the receiver unit with you when you need to dig around the back of the house - and in the summer, this is how it will be. This model is good for everyone except for one thing - it is necessary to control the degree of discharge of the batteries (or accumulators) since the receiver is always, no matter how, consuming.

After the supplied salt batteries leaked (and I was too lazy to drag around for new ones), I powered the bell receiver through an external +3v power supply, which, in fact, gave out about five without load. In order not to risk electronics, I supplied the operating voltage from the AMS1117-2.5v integrated stabilizer. As you can imagine, I'm back where I started.

Discontent

. The call has a single button that can be used to change ringtones. The very first one that is installed by default after power is turned on is one of the loudest, but there is also one more, slightly different and equally loud. As soon as the power is lost, the selection is reset to the default melody. In general, I’m tired of constantly fumbling with the button, and the bell always plays the first melody (which is quite boring) - this is the first inconvenience of this device, however, except for the battery power, in which there would be no problem with resetting the melody.

The second inconvenience stems from the first - when the house is de-energized, the bell does not work, although the remote button has its own power source and is quite functional.

The third thing, in my opinion, is that something else is missing - the outlet under the ceiling is occupied by a single device. And I must say, the small corridor in front of the front door is always dim. During the day or summer (with long, bright evenings) this does not play any significant role, there is enough general light, but to go out at night (smoke), you need to walk a few steps to the nearest switch in complete darkness - matches, a pack, shoes and a jacket at random look is not impressive.

So, I'm left with:

— a case from a small ADSL modem, which took part here; - +5v power supply, removed from the case of one other homemade product; — small radiator; — yellow LEDs from this project; — a single-cell power bank that has been lying idle for three years.

In my drawer I found an unattended case plug from an unknown power supply, and after thinking about it, I decided to try to cross it with the case of an ADSL modem.

The edges of the sawn window were repeatedly moistened with glue, so that the edges of the window softened a little. In addition, I was lucky - the molding of the ADSL modem case required a hole in the power bank case, and instead of just knocking off the protrusion, I decided to assign it as another mounting point. Additional strips of polyethylene foam will increase the contact surface between the two housings. In addition, note that the pocket for soldering 220v conductors in the housing plug is quite deep - this is another piece of luck. First fitting and estimation - what else do I actually want? – I had to invent on the fly, with only a vague idea of ​​the end result in my head. Half of the power bank has lost its standard filling; for me, the +5v weekend is superfluous. Instead of the standard circuit, the only type (that was available) of a charge controller was used.

The network wires of the power supply were soldered to the contact pins, the board itself was glued through a piece of polyethylene foam to a suitable place in the ADSL modem case. And thus, a spacious basement was formed. The power switch is placed in a break in the wires leading to the future load. Those. the load can be disconnected from the battery protection board. The battery itself will be permanently connected to the charging circuit. I planned the button to output contacts for changing melody, and the through hole is intended for installing an LED. I was lucky once again - as I wrote above - there was a fairly spacious basement of the case plug left and the bell board successfully fit into it. This was done right away: - the battery from the old laptop was placed in a homemade battery compartment; — the wires to the button for changing ringtones were soldered; — the +2.8v power supply (supplied to the receiver board) remains the same; - a miniature sound emitter was conveniently placed under the melody change button, and... ... and the imperfection was put back into place - it was late and I had to sleep.

Looking at the super-bright blue LED that flooded the small nook of the hallway, I doubted what I was doing - it seemed like I was complicating everything again.

Lighting.

Through the gaskets, I screwed in a star with a yellow, three-watt LED soldered on it and brought the wires to the back of the radiator. As a driver for the LED, I decided to use the AMC7135 current stabilizer

An integrated driver is essentially a managed key.

Blocking capacitors are used when the connecting wires are long.

A year ago, I accidentally came across an article in which one Anguillian-speaking dude asked another about the possibility of shimming with this driver. I decided that most likely only this one chip would be enough for me, namely, to supply a high level from PIR to Vdd of the AMC7135. Moreover, the earlier article only confirmed this.

The PIR sensor SR501 is also very famous

.

Please note, after clicking on this link, the download of the information sheet will begin.
I will only draw attention to the HL jumper. H – single triggering of the sensor upon the first detection of motion >>> delay of the set time and in case of repeated motion detection, constant increment (increase) of the countdown timer value >>> pause >>> readiness for the next cycle. L – single triggering of the sensor upon the first detection of motion >>> delay of the set time, regardless of whether there was a second detection >>> pause >>> readiness for the next cycle. Naturally I left H.

It's time to see how correct my estimates are.

The PIR motion sensor and the AMC7135 unit were supplied with +4 volts from an external power supply, and the OUTPUT pin of the detector was connected to the Vdd of two combined current drivers. Since each driver produces a current of 350mA, and a three-watt LED consumes 600mA, I decided to use two drivers connected in parallel. But, due to non-optimal installation, and despite the blocking capacitors, the circuit was excited, which was manifested by the unstable brightness of the LED. Therefore, I limited myself to a single driver.

When I had already connected the bell, the sensor and the LED unit to a single power source, I discovered that when playing a melody - the LED picks up the beat - its brightness changes along with the sounds produced. I had to get a small circuit board, and on it I soldered the points distributed from the only power source. A 1000 microfarad capacitor solved the problem with LED blinking.

Pieces of polyurethane foam fixed the radiator with the LED, and the remaining empty windows in the ADSL modem case were covered with a heat-shrink tube in which the cardboard with the AMC7135 was placed.

The LED was covered with a glued transparent cover.

The final fitting showed that there was enough light for emergency lighting.

What could be done differently and the advantages of homemade products.

— on the PIR detector board there is an installation space for a photoresistor, which would not allow the LED to operate under externally lit conditions. But, I suspect that I won’t get these photoresistors this year - the package, apparently, was lost; — I did not remove either the protective diode or the integrated stabilizer from the PIR detector board; — the radiator turned out to be clearly superfluous. When a three-watt LED is powered with half the current, it does not heat up at all, even if the family danced all day in front of the resulting homemade product with bears, gypsies, vodka and a balalaika; - LED, you could choose something else. Yellow, even with a rated current of 600mA, is not particularly bright. This can be seen from the results of my previous homemade product. The brightest turned out to be a green LED at the same current, but I only had yellow ones left; — the set melody will no longer be reset when the 220v power supply is lost; - the entire structure can be taken with you in the summer - I spent last summer (on weekends) at the house, and the built-in lithium cell allows me not to worry too much about the charge; — it turned out to be a complete homemade product without another USB charger and another USB cord; - during the day, the triggered LED is not very visible, the lithium 18650 is constantly connected to the charging circuit, and the yellow color of the glow is absolutely not annoying - so let them dance.

And this is how I implemented the anti-vandal button: and

PS. If I’m lucky and don’t have to resend the photoresistors again, I’ll update the homemade product and add photos to the article.

UPD

Lucky. Photoresistors with parameters “5506” have arrived. I ordered it at random, because nowhere did I find a specific, direct indication of what kind of photoresistor is required for this particular PIR module. As one might expect, this resistor turned out to be unsuitable - the backlight did not turn on even in complete darkness. Therefore, without risking anything, I decided to try two series-connected photoresistors, and then success awaited me. The sensor stopped responding when the overhead light was on, and the remaining eighteen photoresistors will be inherited =)

In general, here it is: peace and quiet, and God's grace =)

Nuances when choosing a wireless call

Like conventional models, wireless doorbells for the front door must be selected based on certain rules, especially if this is the first time purchasing such an item and there is no experience in operating such devices.

Distance

The main quality for a wireless call is the range and strength of the signal that is transmitted from the button to the speaker. If there are 5-10 meters between them, then this indicator is hardly worth paying close attention to, and when you plan to use the device at a distance of 50-150 meters, then it is better to test it before purchasing and agree with the seller about an exchange or return, if necessary This electric bell won't work anyway. This is also quite possible - after all, you cannot see with your eyes whether there are obstacles in the path of the signal or not.

Nutrition

The number of batteries required to operate the device, what types are used, and how often they will have to be changed. It’s unlikely that anyone will answer the last question truthfully, but if the seller really praises the unprecedented efficiency, then it’s worth thinking about. You should not pay special attention to the type of batteries - the main thing is that they can be freely purchased.

Equipment

Everything is simple here - you need to check your passport so that everything is in place. You need to pay special attention to a call equipped with a video eye, several buttons and other additional little things. If at home you discover that some part is missing, then at best you will have to go back, and at worst you will have to prove that this is a factory shortage and not the loss of spare parts due to the fault of the buyer.

Overpayment

Opportunity to purchase a simpler model. If you just need a call to ring, then purchasing a device that can be connected to a computer in order to record your ringtone into it and pay twice or three times for it - most likely there is no point.

Fastening

Velcro can leave traces of glue on the surface if the button is moved, and the screw has to be screwed into the wall or front door. The Velcro may fall off, but the screw can be screwed in only once. Which is better - you need to choose according to the situation.

Manufacturer's warranty

There is nothing particularly broken in simple calls and taking it for repairs may cost more than buying a new device, but it is advisable to clarify this issue. If you purchase a model with a camera, an internal screen and a motion sensor, then you should not only pay attention to the warranty, but also urgently require that all documents be filled out.

Electronics can last 10 years, or they can fail after a couple of months, especially if they are used occasionally.

General impression

In addition to the fact that the device must be beautiful, you need to look at the quality of the materials from which it is made. If you are purchasing a street bell, it is better to choose a button with a vandal-proof housing. Next, pay attention to the melody that you will have to listen to every day, and choose a device from the manufacturer. The last point is quite important - many characteristics of the device and the quality of its warranty service depend on it.

You can see how a wireless street bell works in the following video:

How to make a doorbell based on a broadcast loudspeaker

The device I propose here is, one might say, almost without competition. First of all, it's homemade. Secondly, it is made on the basis of a conventional broadcast loudspeaker, contains a minimum of parts and is capable of delivering a fairly strong sound signal, because the emitter is a speaker. Thirdly, such a signaling device is powered from an autonomous low-voltage source (battery).

Fourthly, the device does not consume energy in standby mode, is absolutely safe and can be used not only as a doorbell, but also as a sound indicator in a security system. Moreover, contact buttons, reed switches or other sensors that operate to close can be located at a distance of up to 100 m from the sound emitter itself.

Due to the small number of parts, there is no point in making a printed circuit board. Installation is carried out using a hinged method, well known to everyone from school physics lessons. The terminals of the speaker, transformer, and 68-kilo-ohm potentiometer are used as supports for soldering.

The volume control of the base speaker functions as a pitch control for the generated signal, which can be set as desired. The switch (toggle switch, button or other contact connector) is placed in a convenient place at the entrance to the entrance, section on the floor, at the entrance door of the apartment.

Any of the low-power germanium MP39 - MP42 will work as a transistor. The choice of resistor is equally not critical: the most common VS, MLT, ULM with a rated power of 0.125 W or more will do. Capacitor - any type (as well as reed switches that work to close, if this sound alarm is to work in a security system).

The volume control of the base speaker acts as a pitch control for the generated signal, which can be set as desired

It happens that a correctly assembled bell does not work when the power is connected. Then you should swap the ends of one of the transformer windings. However, the lack of generation at the audio frequency may also be a consequence of a substandard transistor. In this case, you will have to replace it with another one that has a higher gain.

If the range of pitch adjustment with a potentiometer does not suit the owners, then it can be easily changed by selecting the capacitance of the capacitor. But the sound of this bell also depends on the supply voltage, which can be used, for example, for multi-tone signaling when protecting several objects, personifying callers (“Children” - “Adults”) by introducing a low-resistance resistor into the circuit (in series with one or another switch).

By changing the pitch of the bell, you can also judge the degree of discharge of the power source and promptly replace the worn-out galvanic cell or battery with new ones. Just remember to maintain polarity, because the transistor does not tolerate polarity reversals.

Setting up a call

Based on the size of the button and the functionality of the device itself, the location for their installation is selected. There is not a lot of choice here - the button needs to be clearly visible, and if this is an entrance, then it needs to be clear which door it belongs to.

• The wall near the door. This mounting location is used most often - if the button is Velcro, then its fastening depends on whether the wall is painted or whitewashed. In the first case, the surface must be thoroughly degreased, and in the second, it is better to use a screw.
• Door casing or door leaf. Everything is extremely simple - the usual fastening with a self-tapping screw.
• Through the gate of a private house. Here you need to think more not about where and how to screw the button, but how to protect it from direct rays of the sun, rain and other atmospheric phenomena.

Also, in a private house, it is worth considering a bell with two speakers in order to duplicate the bell signal in the workshop, garden and other places where the owners can be often and for a long time.

When installing speakers inside the house, there are two options - if it’s just a bell, then install it as inconspicuously as possible, but taking into account that you may have to turn off or change the melody, which requires relatively free access to it. If you are using a surveillance monitor and an intercom, then you need to make a separate stand for them or use a niche in the wall for this (if there is one).

Wired

Much more questions arise if you need to connect an electric doorbell to a 220 Volt network. In this case, the actions are similar to connecting a light switch - the phase is connected to the button, and the zero goes directly to the main unit. You can clearly see the wiring of the cores in this diagram:

So, if you have moved into a new building or want to install a doorbell in your house, then you need to proceed as follows:

• Select the most suitable locations to install the button and main unit.
• Turn off the input circuit breakers at the distribution panel.
• Make a hole in the wall for laying the cable that will connect the elements of the circuit. To avoid bumping into other wires when gating, we recommend that you learn how to find a wire in the wall.
• From the finished hole, draw grooves to the installation site of the button and doorbell. You can do without this step if you conduct open wiring in cable channels.
• Fix all the elements on the walls, immediately remove the front cover so that you have access to the terminals for connecting the wires.
• Connect the neutral directly to the main unit.
• Connect the button phase to the doorbell phase.
• Connect the phase from the bell to the corresponding terminal in the distribution box.
• If the apartment has a ground connection and the same terminal is present in the main unit, be sure to ground the bell.
• Check that the connection is correct and turn on the circuit breakers on the panel. Check if the device is working.

This is how you can connect a doorbell in your apartment with your own hands. Sometimes you need to replace the device and the connection technology will be slightly different. If replaced, you will see that there are 4 wires coming from the wall into the apartment. First you need to decide which wire is responsible for what. To do this, we recommend using an indicator. We talked about how to use an indicator screwdriver in the corresponding article.

So, having rung all the wires, most likely the picture will be as follows - on one of the wires you will find a voltage of 220 V, the others will not ring. This means that the following come out from the wall:

1. phase from the network 220 (the indicator worked on it);
2. zero from network 220;
3. wire going to the button;
4. wire coming from it.

To connect a bell with your own hands, you first need to turn off the lights in the apartment, and then connect the 1st and 3rd wires. Accordingly, you must connect the second and fourth wires to the main unit, then turn on the circuit breakers on the panel and check whether the circuit works.

By the way, sometimes it becomes necessary to connect several buttons to one doorbell. In this case, it is recommended to connect them in parallel, as shown in the diagram below:

That's all I wanted to tell you about how to connect a doorbell in an apartment or house with your own hands. We hope that the provided photos, diagrams and videos were clear and useful for you!

It will be useful to read:

• What tools should an electrician have?
• How to save electricity legally
• How to determine phase and zero without instruments

Radio call and remote control of devices

Not so long ago, this miracle of Chinese industry entered our lives, but immediately won our hearts with its simplicity and cheapness. And its simplicity lies in the following: I bought a bell, turned it on, threw it on the closet, and glued the button to the door. That's it, no wires for you, drilling holes for fastenings, etc. . . .

But still, let's look into it and look at the circuit diagram.

Button. Three transistors, 12 volt battery. The high-frequency generator is assembled according to a capacitive three-point circuit, an amplifier-converter. Converts from a frequency of about 433 MHz. What surprised me was the parallel connection of two circuits, one is tuned to the primary frequency of the generator, and the second catches somewhere around the 10th harmonic and is excited at a frequency of 433 MHz. Our Chinese friends again found an original, and most importantly simple solution to the problem using a minimum of details.

Read also: Oscilloscope for Android smartphone

The most interesting thing is that the transmitter does not have a transmitting antenna, of course it is inside, i.e. the outline itself is her. Thanks to the use of ultra-shortwave range, this is quite enough.

Call. The receiver is assembled on a single transistor according to a regenerative detector circuit. The signal received from it goes to the operational amplifier. Next, the signal enters the SOUND CHIP. It is not difficult to guess that he is the shaper of the melodies that we hear. From it to a power amplifier, assembled on one transistor, and into a dynamic head. That's it, I just want to note the relatively small current consumption in standby mode.

They took it apart, looked at it, sorted out the work. All? No, not all! The bell is an almost universal transmitter-receiver circuit. Based on it, you can assemble many other interesting devices.

As an example. The bell controls the light.

We take our call and connect the circuit shown below.

This is a common trigger. When it receives an impulse from a bell, it switches to one of the fixed positions. The output of the trigger is a relay, and a controlled device is connected to the relay, in our case it is an incandescent lamp.

An example of the location of the bell and button.

Location of parts on the printed circuit board.

PS: I was tormented by the question: where can I get power for this circuit? Shouldn't we run a separate line? Here's where you can find a way out - it's in double wiring. If your wiring in the ceiling is designed for two lamps, and the switch has two buttons, the answer came by itself - one button controls the device, and the second is powered by, say, charging from a mobile phone (it is economical).

DIY radio button

Today I will tell you how to make a radio button with your own hands.
I didn’t check the range, but it catches confidently throughout the apartment. With its help, you can control various loads. In my case, I chose a table lamp for the experiment. For work we will need: 1) Soldering iron 2) Lamp 3) some radio parts 4) RF modules

To transmit the radio button signal, cheap and common RF modules are used: receiver and transmitter, photo below

I took this diagram as a basis:

TRANSMITTER

RECEIVER

The radio button is built on common microcontrollers PIC12F675 or (629).

For the button to work, these microcontrollers will need to be flashed. The firmware files are posted at the end of the article.

The transmitter and receiver circuits have been slightly modified, since these circuits are designed to control 4 commands. But as a trial version, I only used one command. The rest I simply didn’t connect.

Transmitter.

Receiver.

Next, we make boards according to the diagram. Unfortunately, the board files were not saved, so it is not possible to post them.

So that you don’t worry about how to connect RF modules, here is their pinout.

TRANSMITTER.

RECEIVER.

I found such a relay on the Internet; it is the one that will turn the lamp on and off.

When connecting a relay, be very careful and attentive, ring the relay before connecting or ask those who know. For example, on my relay, on one side there are 3 outputs, and on the other 2. So where there are 3 outputs, the signal from the transmitter is supplied to the 2 outermost ones, and the load is connected to the middle and 2 on the other side.

Next, solder everything into place.

I made two conclusions in the wire. It is these pins that will be connected to the relay. Just connect everything before plugging the lamp into the outlet.

Now about the operation of the device itself. As you saw in the last photo, and on the receiver circuit itself, there is a K1 toggle switch. Its role is that when it is turned off, when you press the button on the transmitter, the relay on the receiver will turn on our lamp. And as soon as you release the button, the relay will also immediately turn off the lamp. Now if you turn on the toggle switch on the receiver, it goes into command hold mode. That is, if you press the button and release it, the relay will work and the light will remain on all the time until you press the button again.

The diagram shows that there are still three free terminals left, to which you can connect more different loads.

Below: firmware files (TX transmitter, RX receiver), as well as a video of the device working

FIRMWARE Knopka_proshivka.rar (downloads: 928)

VIDEO OF WORK

RF modules can be purchased here: Transmitter and receiver - from 35 to 45 rubles.

Author of the circuit and firmware 4uvak

Become the author of the site, publish your own articles, descriptions of homemade products and pay for the text. Read more here.

RADIO CALL

Recently, many cheap, but interesting and useful electronic devices have appeared on the markets. One of them is a radio doorbell. It is a set of a single transistor transmitter operating at a frequency of about 430 MHz, a modulated quartz oscillator of 32768 Hz and a super-regenerative receiver. Using this 433 MHz CHINESE RADIO CALL, you can control any home appliance.

For example, lamps on the ceiling, or it will be a radio channel from one of the alarm sensors, or a lift on the gate in the garage. I even saw on the Internet the use of a radio call for a radio synchronizer for a photo flash. And such a call costs only $5!

Here is the call diagram, the receiver is a regular super-regenerator (I don’t recommend twisting or adjusting anything - it will only get worse), in extreme cases, you can slightly shift the circuit frequency so as not to exclude the accidental influence of other similar devices operating nearby. You can further increase the noise immunity from other radio calls by replacing the clock quartz with others, for example 40 kHz.

The transmitting part can be powered, after the original miniature 12-volt battery runs out, from a regular 9-volt “crown”, the durability will increase by 2 times, and the price of the battery will decrease accordingly. If necessary, we power the receiving part from the network, using a circuit similar to that in the article “powering a multivibrator from 220V.”

We ask questions about the radio call in the FORUM

Share useful information with your friends:

Wireless doorbell

The transmitter housing is also made of plastic. No protection against moisture is provided. The button is pressed easily with a click. Comes with a 12V 23A battery. Double-sided tape is already installed on the back side. Dimensions.

When the call was turned on, it turned out that the transmission frequency in the old and new devices was the same. When you press the button, 2 bells are triggered simultaneously. But this is not a problem, now there will be three buttons. The call is valid, the main thing is that it works no less than the previous one. Thanks to all.

Maybe someone will find coupons useful?

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.

Radio control system from Chinese radio bell

In electrical goods stores you can purchase a radio-controlled doorbell. The device is manufactured in China and consists of two modules powered from autonomous sources. One of the modules is a wireless bell button, and the second is the bell itself, which plays a piece of music when you press the wireless button. There are many different models and brands of such devices.

Here is one of them, ZAMELST919. The diagram of this device is shown in Figures 1 and 2. The website radiochipi.ru provides a diagram of the wireless button. The circuit is very similar to But unlike them, it transmits only one command, or rather not even a command, but an identification code, which in the circuit of the receiving node (Fig. 2) is used as a command. When the SW1 button is pressed, power is supplied to the button circuit. The CIR2262BM chip is an encoder for transmitting two commands and an identification code.

The identification code is set by a system of jumpers connected to pins one through eight. And for commands, pins 10 and 11 are used, which are not used in this circuit. Therefore, when SW1 is pressed, the transmitter transmits only the identification code, the data of which is transmitted through a low-power transmitter using transistors Q1 and Q2. operating at a frequency of 433.92 MHz. The receiver circuit is shown in Figure 2. The signal is received by a super-regenerative receiving path on Q1Q4 transistors and goes to a decoder on the CIR2267GM chip.

This chip is designed to receive an identification code and decode two commands. The identification code with which the IC compares the received one is set by jumpers on its pins from the first to the eighth. At pin 15, a one appears if the comparison result is positive, and 10 is used for command outputs. These pins are pleasant in this identification code, since the specified jumper circuit is not used. As an output, it uses pin 15 (identification), the unit from which, when receiving a signal from its wireless button, is supplied to the TR6210A sound module, which reproduces a musical fragment.

In principle, the circuit contains almost everything to make a two-command radio control system from a radio call. To do this, you need to make changes to the transmitter (wireless button) circuit, add two buttons SW2 and SW3 as shown in the diagram in Figure 3. The buttons are connected between pins 10. 11 and the power bus of the microcircuit. Now, in order to transmit a command, you need to turn on the power using the previously existing SW1 button, and at the same time, press the SW2 or SW3 button to transmit the command.

Button SW1 can be replaced with a switch that supplies power while working with the radio control system. Changes also need to be made to the receiver circuit. In particular, it is necessary to connect pins 11 and 10 of the CIR2267GM chip to some kind of actuator, for example, to two transistor switches, as shown in Fig. 4.

When a command is received, the corresponding transistor switch will open. In the collector circuits of transistor switches, you can include windings of low-power electromagnetic relays, optocoupler LEDs, or simply resistors to match the logical levels of a given circuit with an external digital circuit that receives a control signal, for example, a circuit of a security device or other equipment. If you don’t need sound when receiving commands, you can simply turn off the ringer speaker or remove it from the circuit altogether.

Read also: Young's module for rubber

Checking operation and reasons why the doorbell in an apartment may not work

It is difficult to make a mistake when connecting an electric doorbell, but it happens. It also happens that if the connection is made correctly, the bell does not work (this may be due to a defective product or lack of power). To check the functionality of the device and identify the reasons why the call may not work, it is necessary to perform diagnostics consisting of the following steps:

1. Turn on the power and check if the bell works.
2. With the power turned on, use a tester to check the presence of voltage on the main unit and on the bell button.
3. When the power is turned off, use a tester or multimeter to test each conductor and determine the integrity of the circuit.
4. If everything is in order with the conductors, check for good contact in the bell button.
5. If, after testing the conductors and checking the electrical connection diagram, the fault persists, then there is a manufacturing defect: return the bell to the store and purchase a new device.

In the case of a wireless device, the cause of the malfunction may be incorrect installation of the batteries, as well as non-compliance with the instructions for the communication range of the main unit and button. Check that the positives and negatives of the battery and the socket match, and also check the installation range.

What to look for when choosing a wireless doorbell

What is a lithium ion battery - device and types

Lighting control schemes using different types of switches

How to connect a two-key switch yourself

How to connect a wire to a single-key switch?

How to properly connect an electric oven and hob: choosing a cable, socket with plug, machine and connection diagram

Why do you need a magnetic starter and how to connect it

WIRELESS CALL 21 | Techniques and Programs

A wireless bell can be used where wiring is difficult to install. The device consists of two modules: a transmitter (remote control) and a receiving part with an electronic gong.

The operating frequency of the transmitter and receiver is about 220 MHz.

Rice. 1. Electrical circuit diagram of the transmitter

The transmitter consists of a carrier frequency generator built on transistor T1 and a coding circuit US1. The US1 circuit of the UM3758-120A can work as a transmitter or receiver depending on the connection of the “MODE” pin. Connecting this pin to +VCC sets the circuit up to function as a transmitter. The signal from the output of this circuit opens transistor T1. The frequency of the carrier generated by the high-frequency generator is determined by the inductance of coil L1 (made on a printed circuit board) and the capacitance of capacitors S3, C4. Coil L1 is also the transmitter antenna. Setting the transmitter code consists of connecting address pins A2-A17 to ground, power plus, or leaving them unconnected. To power the transmitter, use a 12V battery, such as that used in car alarm remotes.

The received signal, after passing through a low-pass filter, is fed to the input of the comparator.

From the output of the comparator, the signal is fed to the RX IMP input of the US2 circuit. Connecting the “MODE” pin to ground sets this circuit to the receiver-decoder operating mode. The address legs of the circuit (A2-A17) must be connected in the same way as in the transmitter. If the received code matches the code transmitted by the transmitter, then the output of circuit US2 will go low for 0.1 s. Transistor T1 will close pin 10 of the US2 integrated circuit to ground, and the gong signal will turn on.

Integrated circuit US2 is a custom circuit from HOLTEK that produces a two-tone gong signal. The HT2820D circuit has tone generators, a clock generator, and analog-to-digital converters in its structure. The elements that directly affect the frequency and color of the reproduced sound are: resistor R4, which determines the frequency of the internal oscillator, and capacitor C4 and resistor R5, on which the duration of the signal depends.

Literature: 100 best radio-electronic circuits; – M: DMK Press, 2004. -352 p.: ill.

How to make a music call on the UMS8 IC with your own hands

This call was made on two microcircuits, which are not currently in short supply. Microcircuit K174UN7 – low-frequency amplifier and microcircuit ISD1210P. The ISD1210P chip is a chip for recording and playing sound for 10 seconds. In this diagram, sound can be recorded directly from the linear output of the tape recorder by connecting it through a resistor to a capacitor. The options for recorded fragments can be very diverse: voice, music, or combined.

In order for the relay to operate after pressing the button, you need to record a sinusoidal signal for 0.5 seconds at the beginning of the file, with a frequency of 15-18 Hz. When you press the bell button, a signal is sent from the chip-corder through the capacitor to the capacitor. Passing through the chain and the logic element creates 1 high level at the output. After passing through a resistor and an amplifier on transistors, it causes the relay to operate to close the contacts.

The resistor adjusts the shutdown delay time. The device in the power supply on a transistor diode and resistors that controls the relay is made according to the “Pause Relay” principle. It is used to turn off the tape recorder at the end of the soundtrack. If you want to record a fragment from a microphone, then use the microphone recording node.

When finished, you can turn it off. The chip-corder chip can be rewritten 100,000 times. The amplifier on K174 UN7 is connected according to a standard circuit, with the introduction of corrective circuits to reduce % n.i. There are no special features in the configuration. A printed circuit board for the power supply was not developed.

Wireless call

A wireless bell can be used where wiring is difficult to install. The device consists of two modules: a transmitter (remote control) and a receiving part with an electronic gong. The operating frequency of the transmitter and receiver is about 220 MHz. Fig. 1. Electrical circuit diagram of the transmitter The transmitter consists of a carrier frequency generator built on transistor T1 and a coding circuit US1. The US1 UM37588120A circuit can work as a transmitter or receiver depending on the connection of the “MODE” pin. Connecting this pin to +VCC sets the circuit up to function as a transmitter. The signal from the output of this circuit opens transistor T1. The carrier frequency generated by the high-frequency generator is determined by the inductance of the coil L1 (made on the printed circuit board) and the capacitance of capacitors C3, C4. Coil L1 is also the transmitter antenna. Setting the transmitter code consists of connecting address pins A2–A17 to ground, power plus, or leaving them unconnected. To power the transmitter, use a 12V battery, such as that used in car alarm remotes. The received signal, after passing through a low-pass filter, is fed to the input of the comparator. From the output of the comparator, the signal is fed to the RX IMP input of the US2 circuit. Connecting the “MODE” pin to ground sets this circuit to the receiver-decoder operating mode. The address legs of the circuit (A2–A17) must be connected in the same way as in the transmitter. If the received code matches the code transmitted by the transmitter, then the output of circuit US2 will go low for 0.1 s. Transistor T1 will close pin 10 of the US2 integrated circuit to ground, and the gong signal will turn on. Fig. 2. Reactive receiver outputs Integrated circuit US2 is a specialized circuit from HOLTEK that produces a two-tone gong signal. The HT2820D circuit has in its structure tone generators, a clock generator, and analog-to-digital converters. The elements that directly affect the frequency and color of the reproduced sound are: resistor R4, which determines the frequency of the internal oscillator, and capacitor C4 and resistor R5, on which the duration of the signal depends. Fig. 3. Receiver wiring diagram Installation of the device begins with soldering jumpers. Then resistors, capacitors and semiconductor elements are installed. A socket is soldered under the US2 integrated circuit. The US1 circuit is soldered directly onto the board. At the end, the receiver module is mounted. The outputs labeled “SREAKER” connect to a speaker with an impedance of 8–15 ohms. It is recommended to use a larger diameter speaker due to sound quality. Then the power is connected - you can use a power supply, for example, a “plug-in” type with a voltage of 9 V and a current of 200 mA. A piece of wire about 30 cm long is connected to the ANT input. It will serve as a receiving antenna. The transmitter is located at a distance of about 1–2 m from the receiver. Next, press the ST1 button on the transmitter and carefully turn the trimmer rotor C3 with a screwdriver made of artificial material. This action should be performed very slowly. Since the transmitter has been tuned, there is a good chance that the gong signal will appear after very minor adjustments to the trimmer capacitance. Then you should increase the distance from the receiver and adjust the trimmer setting again. This action should be repeated several times until the maximum range of the device is obtained. In the trial model, this distance was 30 m in an open area with a new 12 V battery. The transmitter should not be installed near the gate, since its frequency depends on the ambient temperature. The current consumed by the receiver does not exceed 5 mA. To operate the receiver, you can use any number of remote controls with the same code. Fig. 4. Electrical circuit diagram of the receiver

Add a comment

Electrician in the house

Author: admin, 08 Jan 2014

To call, attract attention, or ring the doorbell, various sound and light signals are used. Previously, these were ordinary bells, then electric bells, electromagnetic bells. Nowadays, melodious electronic bells or electronic bells that play melodies, imitate the voices of birds, etc. are increasingly installed for calling and as doorbells. In this article we will look at several simple electronic calling schemes that you can make yourself.

Single tone electronic calls

Single tone doorbell

Single tone doorbell

The diagram shows:

• R1 - resistor MLT-0.5, 10 kOhm
• R2, R4 - resistors MLT-0.5, 2.2 kOhm
• R3 - resistor MLT-0.5, 91 kOhm
• S1 - button A1 0.4-127
• C1, C2 - capacitors K73-17, 4.7 µF, 63 V
• VT1, VT2 - transistors GT109Zh
• VT3 - transistor GT402I
• B1 - speaker MRP 28N-A, 100 Ohm

The diagram shows a call using a multivibrator using bipolar transistors. Bipolar transistors (in the diagram VT1 and VT2) are components of the electronic circuit of the multivibrator. After the S1 button is pressed, the transistor pair (multivibrator) becomes a source of electrical oscillations of sound frequency, which are then transmitted to the reproducing device - the speaker. The frequency of the reproduced sound vibrations in the speaker is equal to the frequency of the multivibrator.

Doorbell of one tone with the ability to adjust the audio frequency of the signal

Ring with adjustable sound frequency

The diagram shows:

• R1, R4 - resistors MLT-0.5, 5.6 kOhm
• R2, R3 - resistors MLT-0.5, 62 kOhm
• R5 - trimming resistor SP3-38B, 47 kOhm
• C1, C2 - capacitors K50-35, 10 µF, 25 V
• S1- button A1 0.4-127
• VT1, VT2 - transistors GT109Zh
• VT3 - transistor GT402I
• B1 - speaker 0.5GD-17 (8 Ohm)

The figure shows a similar circuit of an electronic bell based on an oscillation modulation circuit consisting of two bipolar transistors VT1 and VT2, which is activated after pressing the button. The circuit is powered by a voltage of 9 V. The fundamental difference with the previous circuit is that thanks to a resistor with variable resistance (potentiometer), you can manually set the frequency of reproduced oscillations through an audio speaker connected to the collector of the VT3 transistor. The disadvantage of this circuit is the monotony of the frequencies of sound vibrations induced by the multivibrator.

Electronic bell operating at different voltages

Voltage controlled bell

The diagram shows:

• R1, R3 - resistors MLT-0.5, 2.4 kOhm
• R2 - resistor MLT-0.5, 100 kOhm
• C1, C2 - capacitors K73-17, 4.7 µF, 63 V
• VT1, VT2 - transistors GT109Zh
• VT3 - transistor GT402I
• B1 - speaker MRP 28N-A, 100 Ohm

The figure shows a diagram of an electronic bell, the operating principle of which is based on the use of different voltage values. The basis of the electronic bell multivibrator circuit consists of two bipolar transistors (in the circuit VT1 and VT2), this is structurally similar to the circuits presented earlier. While the potential difference is insufficient, the transistor is closed, as soon as the voltage is within the desired value at the XT1 terminals, then the transistor opens to allow current to flow and the speaker turns on.

Circuits of electronic doorbells with a complex sound signal

Bim-bom doorbell

If you are not satisfied with the monophonic sound of the doorbell, then you can install the electronic circuit shown in the diagram below, creating a “bim-bom” type sound of the bell. The operating principle of this circuit is based on the operation of a transistor multivibrator. Unlike previous schemes, this one allows you not only to create sound vibrations of various frequencies, but also to set the rhythm and pause time between the sound signals of the electronic call.

Bim-bom bell

The diagram shows:

• T1 - step-down transformer TA-2-127/220-50 (pins 3 and 4 (~7V))
• S1 - button A1 0.4-127
• D1-D5 - diodes D226
• C1 - capacitor K50-16, 1000 µF, 16V
• C2, C3 - capacitor K50-16, 10 µF, 16V
• R1, R2 - trimming resistors SP3-38B, 470 kOhm
• R3, R6 - resistors MLT-0.5, 10 kOhm
• R4, R5 - resistors MLT-0.5, 33 kOhm
• R7 - resistor MLT-0.5, 1 kOhm
• R8 - resistor MLT-0.5, 470 Ohm
• VT1, VT2, VT3 - KT630D transistors
• VT4 - transistor KT630G

In the circuit diagram, the multivibrator circuit is formed using bipolar transistors VT1 and VT2. The frequency of formation of rectangular pulses is set using resistors with variable resistance (potentiometers) R1 and R2. Also, by changing the resistance of the adjustment resistors R1 and R2, you can set the pause time and sound duration of the signal transmitted to the playback speaker; in our case, the sound duration can reach from three seconds to create a continuous sound of the outgoing sound signal.

This circuit is based on a multivibrator using bipolar transistors, in which rectangular pulses of audio frequency are generated. The resulting pulses passing through the repeater on the emitter of the bipolar transistor VT3 enter the cascade of the transistor VT4 and at this moment they close the circuit and the bell makes a sound - “bim-bom”. In more detail, the principle of creating a sound signal of different tones and sounds can be described as follows: after pressing the S1 button, transistor VT3 is open to allow current to flow to transistor VT4. This creates the basis for the occurrence of electrical impulses in the multivibrator, which are transmitted to the reproducing speaker and create audio frequency oscillations in it. Let's call this signal primary. If transistor VT2 is open, then transistors VT3 and VT4 are locked accordingly. This creates a situation where the bell circuit is broken, at which point the multivibrator generates an audio signal of a different frequency and tone. The duration of pressing the bell button also affects the frequency of the generated sound vibrations. To avoid excessive potential differences in the circuit, as well as inductive amplitude voltage fluctuations, a diode D5 is built into the circuit, which also ensures the safe operation of the VT4 transistor.

Electronic doorbell with triple tone alarm

Triple ringer

The diagram shows:

• S1, S2, S3 - buttons A1 0.4-127
• D1 - Zener diode D814V
• D2 - zener diode D816A
• D3 - zener diode KS468A
• D4 - diode D226G
• R1 - resistor MLT-0.5, 5.1 kOhm
• R2, R4, R7 - resistors MLT-0.5, 4.7 kOhm
• R3 - resistor MLT-0.5, 2.4 kOhm
• R5, R6 - resistors MLT-0.5, 120 kOhm
• R8 - resistor MLT-0.5, 820 Ohm
• R9 - resistor MLT-0.5, 560 Ohm
• C1, C2 - capacitors K73-17, 4.7 µF, 63 V
• VT1, VT2 - transistors KT630G
• VT3, VT4 - GT402I transistors

Schematic diagram of an electronic doorbell, which simulates oscillations of sound frequencies of several tones, using a multivibrator assembled on bipolar transistors. By varying the pressing of the S1, S2 and S3 buttons in the multivibrator, current pulses are generated, which, when transmitted to the playback speaker, create oscillations with a frequency of 2.0, 1.0 and 0.3 kHz.

These circuits are fundamentally simple to design and install, and therefore will not cause any difficulties even for novice radio amateurs. An item assembled with your own hands is always valued higher than something bought in a store, so create, invent, try. In addition, by selecting ohmic resistance or parameters of bipolar transistors, you can achieve a unique sound for electronic doorbell models.

It will be interesting to read:

Two-wire circuit for turning on light from two places

Intercom

Mosquito Repeller

Headings: Useful devices, Electronic devices, Electrical circuits Tags: do it yourself, electronics

Wireless doorbell

Contents: Receiver 2 buttons 2 batteries 23A 12V 2 double-sided tape Let's start with the receiver. The case is made of plastic, it looks normal. On the front side there are 3 LEDs, they light up when a call comes in, and holes from the speaker. On the back side there is a compartment for two AA batteries. On the right side there is a switch of 3 positions: top - all melodies play in turn; medium - no sound, only LEDs; lower - the melody that was last played in the upper position of the switch is played. LED operation.

The transmitter housing is also made of plastic. No protection against moisture is provided. The button is pressed easily with a click. Supplied with 12V 23A battery. There is already double-sided tape installed on the reverse side. Dimensions.