Transformer data for the subscriber loudspeaker. Features of using loudspeakers in public address systems. Classification of loudspeakers for public address systems

As it turned out, they do this too. And for money, which is typical
In the process of studying search results on the topic of subscriber loudspeakers, I came across an advertisement about the cost of repairing these same loudspeakers. True, in Yaroslavl region Surprisingly, the prices turned out to be quite affordable. The range is from 8 to 90 rubles. For those interested, here is the proof link.

For my part, I’ll note that a wired broadcast receiver is actually a very useful thing (don’t laugh!), but it requires improvement due to obsolescence. Because, using the example of the three-program “Riga” loudspeaker, it is clear that firstly, the connectors need to be changed. Since tape recorders with an input in the form of a plug, similar to the current one for an electrical outlet, are not currently used. Therefore, it makes sense to either solder the output to the tape recorder to a 3.5 mm jack socket, or at least make the output to “crocodile” clips (for reasons of convenience, the loudspeaker is connected to the radio network by “crocodiles”).

Let's move on. This speaker is powered by 220 volts. Power cords of the type that were used then are no longer produced in principle. Because they are not needed. Therefore, we remove the “male” from the case and solder a normal power cord with a plug.

There is a separate conversation with the radio network input. The option that was used before was a wire with a plug (like our electrical network), which was plugged into a radio socket. Now often these radio sockets are either not there (removed during the next repair) or they are inoperative due to damage to the wiring. In my case, it was both: the socket had been removed a long time ago, in addition, the radio wiring was damaged somewhere. I had to look for the entrance of the radio network to the apartment, and use a twisted pair cable (since there was nothing else at hand) to carry out a wired network into the room. Hanging up the socket was, firstly, lazy, and secondly, pointless, because... At first, an 8-ohm speaker with a variable resistor soldered to it served as a radio loudspeaker. It was more convenient to crimp the knife socket on the supporting pair and solder the “crocodiles” to the homemade loudspeaker. Cheap and cheerful. “Crocodiles” were also soldered to the input of the loudspeaker (no longer homemade).

I must say, prisoners of the ITU “ White Swan”, that in Daugavpils (where, in fact, these loudspeakers were produced), they worked conscientiously. Because there are no complaints about the quality of the assembly - after cleaning the board from dust, it turned out that only one coil on the board needs to be checked (it began to give an abrupt change in volume instead of a smooth one), and, apparently, after the loudspeaker was thrown off the shelf by the shady cat of the previous ones owners.:)

Well, for a snack - the promised one electronic circuit. You can evaluate the degree of, let's say, ingenuity of those who designed this receiver

May 1, 2010 at 03:48 pm

Second life of wired radio

• DIY or Do It Yourself

While sorting out my grandmother's things, I came across a wired radio (subscriber loudspeaker), which served faithfully for about 30 years. Of course, it cannot be called an outstanding creation of Soviet industrial design, but it would be a shame to throw it away.

On the other hand, where can it be applied? There is no subscriber radio point in my apartment, and I have no particular desire to listen to national radio broadcasts. If only you could listen to what you want and it’s like on the radio... And, actually, why not? And then I came up with the idea of ​​​​making a regular speaker out of a subscriber loudspeaker! Well, that is. an ordinary mono speaker connected to a sound source through an amplifier.

What did I get?

To determine the device model, we had to search by appearance with complete search, because neither the name of the model nor the manufacturer was listed on the case. Fortunately, the search was short-lived - I got the Donbass subscriber loudspeaker.

In my case, however, it is black and yellow, without a handle, without a back wall, without a plug and with a twisted wire.

Modernization plan

The essence of the upgrade is to integrate the amplifier into the speaker housing and connect any sound source to the input. The issue with the amplifier was resolved quite simply: remove it from unnecessary Chinese Taiwanese speakers.

It should be noted that using an amplifier made from Taiwanese speakers is not the best option in terms of sound quality, but it is the simplest and cheapest (provided such speakers are available).

The main issue of modernization was the sound source. You can connect anything to the input: portable radio, player, phone, laptop. At the same time, I didn’t want to clutter the device functionally, but on the contrary, to make it as simple and convenient to use as possible. A good option It might be possible to use the AirPort Express audio output, but it is already in use, and I didn’t want to buy another router. The best option found unexpectedly.

It was decided to hang the loudspeaker in the kitchen on the wall where the TV was originally planned to be hung. There were regular and TV sockets for the TV, and the TV cable from the socket goes to another room to a single cable switching point for the TV and modem.

What if you send sound through a coaxial cable from the room to the kitchen? From the room I connect everything I want, and at the output I simply amplify the sound. It’s clear that coax is far from oxygen-free copper, but I’m not going to listen to hi-fi over a loudspeaker.

Modernization

Well, let's get started. Of the three parts in the loudspeaker housing: speaker, variable resistor and transformer, we leave only the speaker. More precisely, first you should remove all the parts and wash off the plaque from the body stormy youth and then insert back only the one you need. I want to warn you right away: The loudspeaker speaker produces sound in the range of approximately 160-6300 Hz, so if you are going to listen to your favorite music through such a speaker, then it will sound at least not entirely authentic.

We disassemble the Taiwanese speakers: from the one with the volume control, we remove the board and transformer. In my case, the speaker in the column was not soldered, but connected through a connector. We unsolder the wires together with the connector from the speaker and solder them to the speaker speaker. The transformer from the speakers also has a connector, and therefore practically without any problems it replaced the previous one in the speaker housing. Let's move on to the board.

We unsolder the second column (wires on the left), and instead of the wires from the jack (on the right), we solder the original wire from the subscriber device. The main thing here is to find which channel goes to the speaker and solder to it. The second channel can be grounded. Next, we unsolder the variable resistor, and in its place we solder three wires (again, from the side of the channel going to the speaker).

We solder these wires to a variable resistor of the same value, but with a switch. And we attach the variable resistor itself to the place of the previous one in the housing. The switch will serve as a button to turn on the amplification circuit. As a result, when you turn the knob, the amplifier will first turn on, and then the volume will be adjusted. Interestingly, the amp switch on the speakers I used is located after the transformer. Those. when these speakers are connected to the network, regardless of whether the circuit itself is turned on or not, they consume their two watts. Actually, that’s why I installed the switch not instead of a button, but in front of the transformer.

I attached the board and power connector to the case with silicone glue, and chose the most suitable one from old Soviet pens. As a result, this is what the loudspeaker looks like from the inside:

And this is from the outside:

Let's not forget about the sockets: we replace the standard white ones with black and yellow ones that are more suitable in color:

Switching point (adapter: coaxial - monojack, extension cord: female jack - male jack):

In progress

In operation, a regular subscriber loudspeaker behaves well - it regularly reproduces the sound supplied to the input, coloring it with the effect of a wired radio. Automatically, the sound source in the form of a laptop became the director's console, because When you connect a microphone, you can broadcast from the room to the kitchen: send greetings, play your favorite music, and also communicate with radio listeners. The only downside that can be noted is the characteristic background of the amplifier made from cheap Taiwanese speakers.

Behind the director's console.

Often the mailbox is located far from the place where the person constantly waiting for this mail is located. The scheme that I present to you was born at the request of such a waiter. At the company where I work, an assistant is in charge of mail. workplace which is located in the reception area on the second floor, and the mailbox hangs on the first floor. And the assistant, in anticipation of the possible arrival of mail, began to shuttle between the first and second floors. This stressed her out a lot, because she also has another job.

Mailbox inside. Photo

The subscriber loudspeaker is also located in the same housing as the controller. But this necessary measure, since it is impossible to find a beautiful modern building. Yes, and purchasing a modern subscriber loudspeaker is problematic. So the decision was made to “create” a device based on modern Genius computer speakers. The purchased speakers were screwed together and covered with pieces of plastic “for beauty.”

Mailbox controller and indoor speaker. Scheme

How does the controller work? Note, not the controller, but the controller. I scratched the bottom of the barrel and found the details that determined the scheme and the entire structure. The first part is a small-sized network transformer with a power of 2 W and an output voltage of 24 volts. The second is the RES-55A relay.

The circuit is built on the same principle as other similar circuits (see below in the literature). Power supply - PSU (T2, VD7, R15, C6 and C7), memory cell - trigger (K1), light circuit and sound indication(DD1, BF1, HL1, VT1 and VT2), as well as a remote control and display panel (SB2, HL2).

The circuit is based on the effect that the relay has different operating current and holding current. At the initial moment, a voltage of approximately + 25 volts from the power supply passes through the closed contacts of relay K1 and then to the status indicator HL1 through resistor R13, and to the indicator installed in the remote control button SB2 - HL2 through resistor R17 and relay winding K1. The current passing through relay K1 is too small to operate. The indicators glow steadily, indicating that the circuit is turned on and in standby mode. No current passes through VD7. When you press the SB2 “Mail” button in the mailbox, the power supply voltage is fully applied to the winding of relay K1, the current is limited by R15 in the power supply and the relay is activated. The latter, with its contacts K1.1, opens up the collector and emitter of transistor VT2 and through the current-limiting resistor R14 and diode VD7 is self-blocking. The voltage on the relay, after operation, decreases to 13 volts, since a VD6 zener diode is installed after R14. The voltage from this zener diode is also supplied to DD1 and the generators are started. This voltage is also supplied to the chain - R5, C1, VD2. The current pulse generated when charging C1, through the open diode VD2, forces the 60”/2” generator, assembled on DD1.1 and DD1.2, to open its output and, through the closed diode VD4, allow the operation of the 2000 Hz generator, assembled on DD1.5 and DD1 .6 and further convert this frequency into sound using the BF1 piezoceramic speaker. There is a variable resistor R10 in series with BF1 - this is the volume control. The value of this resistor is selected so that at a minimum volume, a quiet sound can still be heard. The 0.5”/0.5” generator, assembled on DD1.3 and DD1.4, also starts, which makes the sound intermittent through the VD5 diode, and through the resistor R9 controls the VT1, VT2 keys and they make the HL1 and HL2 indicators blink showing the postman and the waiter that the scheme worked. The waiter can put the circuit into standby mode by pressing the SB1 “Reset” button, this will short-circuit the winding of relay K1, its contacts will return to their original state. In the first version, the circuit had a different body, and there was a “rubber” button in it. The device was created in 2003 and served for 10 years. After a thunderstorm, a diode burned out - VD7, which was type KD522B.

The device is assembled. Photo

The subscriber loudspeaker was assembled from a variable resistor and from speakers BA1 and BA2 taken from the speakers. Transformer T1 was taken from an old “donor”.

Device connectors. Photo

Details: SB1 is a converted "Power" switch that has been "corrupted" into a button. R10 is a small-sized variable type SPO-0.5, SP3-4bM and is installed in the hole where there was previously a headphone jack. K1 – relay type RES-55A passport 0002. XS1 and XS2 – RJ-12 telephone connectors. XR1 is a six-wire RJ-45 connector, XR2 is an RJ-12 connector.

Structurally, the subscriber loudspeaker is a housing containing: a loudspeaker head, a matching transformer, a variable resistor that acts as a volume control, and a cord with a plug for connecting it to the sockets of the wired broadcasting network.

The picture shows structural scheme typical indoor loudspeaker.

Electrical diagram of a typical indoor speaker

The loudspeaker head is the main element of the subscriber loudspeaker, on which its electroacoustic parameters and sound quality depend. Subscriber loudspeakers use only electrodynamic type heads, the operating principle of which is described in section.

It should be noted that for a number of types of subscriber loudspeakers, special loudspeaker heads have been developed: for AG of the third complexity group - 0.5GD-42 and 1G D-55, for AG of the second complexity group - 1GD-52, the parameters of which are given in the section Loudspeaker Heads. This is explained by the fact that the AG must provide special requirements for the electroacoustic parameters necessary for reproducing transmissions of a high-quality wired broadcast network (in small-volume enclosures). Mainly, the development and production of such heads is carried out by manufacturers of subscriber loudspeakers.

The domestic wire broadcasting network is designed to transmit low-frequency channel audio signals with maximum (peak) voltage values ​​of 30 V (for Moscow - 15 V). The specified voltages cannot be supplied to the speaker heads, as this will lead to overload and failure. building. For subscriber loudspeakers, the permissible power consumption is established: for AG of the third complexity group no more than 0.25 W, for AG of the second complexity group no more than 0.26 W. From the above data, you can determine the total electrical resistance of the subscriber loudspeaker: R=U 2 /P, where R is the total electrical resistance of the AG, U is the supplied voltage, P is the permissible power consumption.

Hence for AG of the third complexity group R=30 2 /0.15=6000 Ohm, for AG of the second complexity group R=30 2 /0.25 = 3600 Ohm.

Electrodynamic loudspeaker drivers typically have a total input electrical impedance of 6 and 8 ohms. To connect a low-impedance dynamic head to a wired broadcast network, an output transformer is used, in the secondary circuit of which the loudspeaker head is connected. A voltage of 30 or 15 V is supplied to the input of the primary winding of the transformer. Thus, the output transformer allows us to solve the problem of matching the required total input electrical resistance of the subscriber loudspeaker and the loudspeaker head.

The transformer consists of the following parts: core, frame, windings. The core is assembled from stamped plates. The frame is made of getinax. The windings are made of copper wire with enamel insulation, for example PEL, PE>V, PEVT, etc. Sheet steel E4211, E4212, E4213 is used for the plates. The standard size of the plates for TAG-SH and TAG-P transformers is W 6x6; W 6x8, etc.

At the Izumrud Production Association in Stavropol, miniature transformers for AG of all complexity groups have been developed and manufactured.

Coefficient useful action for low-power transformers is 0.85. Currently, the task is to increase the efficiency of transformers for AG in order to improve their parameters.

The volume control in the subscriber speaker is used to smoothly change the volume of broadcasts from minimum to maximum level. It represents a variable resistance. When the regulator axis is rotated, its electrical resistance changes and voltages are redistributed between the loudspeaker head and the regulator. As a result, a voltage from zero to maximum is applied to the loudspeaker head and, in accordance with this, the sound volume level also changes from zero to maximum.

The electrical cord is designed to connect the subscriber loudspeaker to the wired broadcast network; it is made in accordance with GOST 7399-80. ShPP brand cord (polyethylene insulated cord with parallel conductors without dividing the base, low-current, designed for alternating voltage up to 110 V). The design of the plug must ensure the connection of the AG to the socket of the wired broadcasting network, without allowing it to be accidentally plugged into the alternating current network.

The structural basis of any AG is the body. It provides unification individual elements AG into a single structure with specified electroacoustic and operational parameters. Most modern AGs are formed on the basis of plastic or impact-resistant polystyrene casings, characterized by high manufacturability, a wide variety of color and design solutions, and fairly high acoustic properties. The dimensions and design of the housing also largely determine the resulting values ​​of the main electro-acoustic parameters of the AG, such as the shape of the frequency response, the value of sound pressure, as well as high-quality work on high levels volume. The vast majority of indoor loudspeakers use an enclosure open type. It provides communication between the rear side of the loudspeaker head and the surrounding air environment through radiating holes in the rear steak of the housing.

I have always had an interest in subscriber loudspeakers (CA). They were produced in all sorts of shapes and colors. former USSR! Now these products are smoothly migrating to flea markets, where they can often be seen and, most importantly, bought inexpensively. Inside the case, as a rule, there is a transformer for matching AC voltage broadcasting network (~30V) audio range with speaker coil resistance (often 8 ohms 2 W). The domestic industry also produced more “sophisticated” versions of AG for two or three channels of wired broadcasting. Currently, almost all populated areas three-program wire broadcasting was introduced. Programs 2 and 3 are transmitted at carrier frequencies of 78 and 120 kHz with amplitude modulation. To transmit these programs, wired broadcasting stations are equipped with special transmitters.

I was attracted to AG not so much for its original intended purpose, but for the sake of the housing, where a fairly large electronic device can be built in. And dynamics with a transformer, at the same time, are not difficult to find a use for, teaching the device to sing, talk or make sounds. This is what such a device with a built-in microcontroller board and LCD might look like (Figure 1).

I remember making an apartment bell with a melody and additional functions, such as: determining “friend or foe” by the manner of pressing the button, turning on the corridor lighting, when the door opening sensor is triggered, and some others, which to this day cannot be found in purchased products .

But one day I came across an unusual AG. In addition to the standard variable resistor matching transformer and speaker for such products, it contained an electronic board, the purpose of which was difficult to understand at first glance. After googling, I came across a website of Kazakhstani radio amateurs: Kazakhstan computer portal - Articles Calling device UV_2_14 UHL4_2, USSR.htm. (see Attachment). The material is quite informative and sufficiently illustrated, for which we thank its author, Mikhail Dmitrienko. I was somewhat offended by Mikhail’s expression: “The plant was destroyed", because in my memory I don’t remember such an expression being used for Soviet productions electronic industry located on the territory of the Russian Federation. Here, much more often, the democratic, so to speak, term was used “ fell apart“... Well, okay, in general, there was a desire to study in more detail this pearl of the electronics industry of the Kazakh SSR, especially since I had several of these AGs at my disposal and, naturally, there was a desire to use them “to the fullest”!

As a result of the research, the diagram in Fig. 2 appeared.

Rice. 2

Not being particularly competent in the field of passive filters, I can say that testing with a generator showed transmission of frequencies near 16500 Hz to the detector on the VD1 diode. Pressing the SW button results in a siren-like sound being heard in the small speaker, which is understandable, given the presence of positive feedback using resistor R10. When the resistance of potentiometer R3 is reduced, the generation of a frequency of 1100 Hz of the generator on transistor VT1 also occurs (it is possible that the circuit on this transistor is an active low-pass filter), which, apparently, with this decrease, switches from amplifier to generator mode. Unfortunately, it was not possible to reproduce sounds when modulating the 16500 Hz carrier with any frequencies of 30-3000 Hz from the low frequency range, which was originally expected. What is the “trick” here, perhaps, will be answered by the corresponding topic on the forum, but for now it would be useful to imagine how this circuit could be useful when applied partially or completely, “as is,” using a modern element base.

1. The circuit can be used as a digital data receiver with a carrier frequency of 16500 Hz modulated by UART at speeds of 2400-100 baud. By increasing the carrier frequency, the required filter bandwidth can be shifted to 60-50 kHz (which is achieved by replacing capacitors C1, C2, C3, C4) and the reception speed of such data can be increased.
2. By adding appropriate matching devices in the form of HF transformers on this base, you can organize a modem for transmitting digital information through the wires of both the subscriber radio network and ~220V power wires, thus implementing a transponder for transmitting information through these interesting communication channels.
3. Finally, using the direct conversion technique, for example, described in the literature [2], it is possible to implement radio modems on the basis of this board for communication at convenient frequencies in the HF and VHF amateur radio bands, since it is for transceivers of this kind that a high-quality block of low-pass filters is critical.

Despite the widespread use of FM radio broadcasting, with its excellent quality of sound reproduction and stereo, in my opinion, it is too early to write off the technology of a traditional radio broadcast network. It was equipped with both residential and non-residential buildings, and still, probably, they are equipped in accordance with the current SNIPs. This means that the corresponding wires (like the well-known “noodles”) were laid by the projects and laid in the interblock spaces of high-rise buildings. Often, radio broadcast network wires have also been preserved in villages or remote towns, where FM broadcasting may be completely absent. There, the wire lines for the AG still coexist on common poles with the intra-village electrical wiring (even in the form of a field wire twisted into a pair, mounted on miniature insulators). The use of this “bonus” from the Soviet past can now be more diverse and include a low-performance information communication channel, as well as a highly important functions security and fire alarm systems and transmission of emergency alerts.

NOTE: All inductances in the diagram are non-standard, wound on cup cores made of ferrite of an unknown brand, the inductances were measured experimentally and are indicated on schematic diagram. All permanent resistors are MLT brand 0.5 W with the values ​​indicated in the diagram. For a description of the dynamic heads, see the attachment.

Literature:

1. Eng. V. Bazylev, engineer G. Skrobot, Three-program loudspeaker, Zh. Radio No. 1 1971
2. Polyakov V.T. Radio amateurs about direct conversion technology, Publishing House of the Central Committee of DOSAAF USSR “Patriot”. 1990
3. Kazakhstan computer portal - Articles Calling device UV_2_14 UHL4_2, USSR.htm

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
VT1, VT4	Bipolar transistor	MP41	2			To notepad
VT2, VT3	Bipolar transistor	KT315B	2			To notepad
VD1	Diode	KD103V	1			To notepad
VD2-VD5	Diode	D104	4			To notepad
D	Zener diode	KS407A	1			To notepad
C1	Capacitor	620 pF	1	Mica		To notepad
C2-C4	Capacitor	1200 pF	3	Mica		To notepad
C5	Capacitor	47 nF	1			To notepad
C6	Capacitor	2.2 nF	1			To notepad
C7	Capacitor	68 nF	1			To notepad
C8, C9	Electrolytic capacitor	20 µF	2			To notepad
C10	Capacitor	4.3 nF	1	Mica		To notepad
R	Variable resistor	68 kOhm	1			To notepad
R1	Resistor	240 kOhm	1			To notepad
R2	Resistor	1.3 kOhm	1			To notepad
R3	Trimmer resistor	6.8 kOhm	1			To notepad
R4	Resistor	68 kOhm	1