Electrical diagram of a negotiation device for two wires. Home phone network from two phones. Bilateral Concept

A simple negotiation device can be collected from two subscriber loudspeakers. Its use can be different, in the country, in the house, in the apartment, etc. In some cases, the use of a radio channel or mobile communications Unreasonable, and often not possible. Especially if a constant round-the-clock connection is required. For this, this design has been developed. The main advantage of the negotiation device is that Va1 and Va2 loudspeakers are both microphones and loudspeaker. There are two options for the manufacture of the device. In the first version, only one amplifier is used.

The device consists of a pre-amplifier on the VT1 and the power amplifier assembled on the IC K174UN7. Switching modes Reception - Transmission occurs using the S1 switch, the switch is available only by one subscriber, with which you can connect the loudspeakers alternately to the input or output of the amplifier. The simplified scheme of the second variant of the intercomder is shown in the following figure.

In this case, the amplifiers M and switches S are set in each loudspeaker. Switching from receiving transmission can be made to each subscriber. When the S switcher is pressed, the loudspeaker is used as a microphone and connects to the input of the pre-amplifier through the separator capacitor C1. Pre-amplifier Candored on the VT1 transistor. Variable resistor R1 determines the level of feedback and sensitivity at the input of the cascade. From the exit of the pre-amplifier through the variable resistor R5, the signal comes to the power amplifier collected on the DA1 microcircuit.

Using the resistor R5, the output power is adjusted. From the output of the amplifier, the signal enters the line and, through a pressed S2 button, enters the loudspeaker, which in this case is used in its intended purpose. It is necessary to pay attention to the fact that the line can be both two wired and single-wire, if the ground is used as the second wire. Grounding can serve as water pipes, heating or simply metal rod drove into the ground.

The maintenance of the meeting device is carried out from the network nine volt power supply or galvanic elements. The correctly assembled device starts to work immediately, if necessary, you can adjust the sensitivity using the resistor R1, and using the R5 resistor to adjust the output power. Me Miniature loudspeakers are used in which lowering transformers removed, instead of the volume controllers, the S1, 2 of the type of P2K without fixation are installed. Author: Valery Ivanov.

Often, in the practice of a novice radio amateur, there is a need to assemble a simple wire negotiation device, say, for the country area, so that you can deal with a conversation from the room with those who are in the kitchen, in a bath, a shopping block or with the neighbors in the country. To solve such a problem, two variants of the device are proposed - for two and three subscribers.

Each of the intercoms are collected from the available parts, it practically does not require establishing and can provide duplex communication at a distance of up to 200 m. In operation they are maximally reminded ordinary phonesSince the main part in them is a good handset.

Of course, Ideally, it would be nice to use a spoiled telephone with a lever switch on which a tube is resting, but in the absence of this, any case with a toggleter installed on it is running on it manually.

Before you go to acquaintance with the variants of the proposed devices, consider the operation of the call generator or simply the call generator (GW). Its schematic diagram is shown in Fig. one.

The generator is an asymmetrical multivibrator made on transistors of different structures. It is connected to the power source and load with three wires through the clamps "out.", "Commonly.", And "+".

The frequency of the generator is unstable and depends on the supply voltage, load resistance and resistor R2. With the nominal numbers indicated on the scheme, it is within 500 ... 2000 Hz. The resistance of the resistor R1 depends on the volume of the sound - than it is more, the sound is louder. However, with too much resistance (more than 1 com), a breakdown of oscillations of the generator is possible.

The assembled generator should be checked and set together with the power source (GB1 battery with a voltage of 3 ... 12 B) and telephone caps, which will be used in real device. Establishment lies in the selection of resistors R1 and R2 in order to obtain a loud and distinct sound.

We will tell you more about the operation of the multivibrator. After turning on the power, the transistors VT1 and VT2 are closed, as based on the transistor VT1 zero potential. The C1 capacitor begins to charge through the R2 resistor and the chain of the connected elements R1.BF1. This process flows linearly until the voltage on the C1 capacitor does not exceed the VT1 transistor opening threshold.

As soon as the VT1 transistor begins to open, and the VT2 opens next. At the point "Out." A positive voltage appears. Through the resistor R1 it consists with a voltage on the C1 condenser and is supplied to the VT1 transistor database. And the one, in turn, opens even more, and even more opens VT2. An avalanche-shaped process arises, which leads to the fact that the transistors VT1 and VT2 are included in the saturation, and the BF1 telephone capxyl is made through the open transistor VT2, the full battery voltage is applied.

This state is unstable and will continue until the C1 condenser recharges through the R1 resistor. As soon as the capacitor recaptures, it will not be able to provide the current of the VT1 transistor database, sufficient to maintain the saturation mode. VT1 will start closing, closing and VT2. Positive tension at the point "Out." It will decline, thereby reducing the voltage based on VT1, - it closes even more, fascinating and VT2.

Avalanche-like process is again, as a result, the transistors are completely closed. The VT1 base is under negative voltage provided by the C1 capacitor, which has purchased it during recharging. This voltage is not persistent constant, and due to the current via the resistor R2 smoothly goes into zero and then, reaching a positive value sufficient to open VT1, causes a new cycle.

Thus, the multivibrator periodically connects the telephone cap to the battery, providing sound radiation. It should be paid to the fact that the current consumed from the battery is also made by the generator frequency, and if the second telephone capal is sequentially included with the battery, it will also emit sound.

O. Khovaiko, Moscow.

Often, at negotiations between objects, the negotiations have heard all correspondents simultaneously. This negotiation device (PU) makes it possible to conduct such negotiations between three objects.

The negotiation device for building a simple scheme, and it is possible to make it in a few hours. Convenience is that the loudspeaker is used as a speech microphone. To manage reception / transmission modes, only one button running on switching is used. This intercom is very simple and in the installation. The author of these lines used it in the production of works at a construction site, in elevators, as well as in autocoisters and in the village for communication within the economy. The PU provides sustainable bond with great reliability and with large fluctuations in the supply voltage -220 V. Collected panels of the negotiation device in small boxes. Their size depends on the dynamics used. The only flaw this device It is that it is necessary to speak from a distance of not more than 0.5 m. To simplify the scheme and switching, the author abandoned the "call" button, as practice shows that there is no need. Call is carried out by voice.

The PU scheme is shown in the figure. Pre-amplifier assembled on Type VT1 and VT2 transistors

CT315 C at at least 80, the end amplifier is on the K174UN4A (b) chip. It is possible to use other microcircuits. It all depends on the material capabilities and technical requirements. Power is carried out from the network through the usual diode bridge. The supply voltage of 4.5-9 V. When nutrition from batteries of type A-3336, their charge was enough for 7-10 days. If you wish, you can use any batteries with a voltage of 6 V. In this case, it is necessary to provide for their continuous recharging (rural version). To conduct wiring between objects, it is not necessary to apply shielded wire. The author in the rural version used one wire, and instead of the second-survey.

After turning on the power, the device is immediately ready to work. For a conversation, you must click the "Conversation" button at the subscriber who wants to make a message. Its loudspeaker connects to the input of the negotiation device - and everyone hears his message. Next, the button is released, and you can listen to the answer. There is also a parallel conversation of two or more subscribers.

The resistance of the resistor R1 is selected at maximum strengthening without excitation. As T1, you can use any transformer calculated on the power of 15-25 W and the output voltage 6 V, for example, TC12. All loudspeakers like 0.5 GDSh2 - 8 Ohm.

O. G. Rashitov, Kiev

Wired connection with the help of a negotiation device (intercom) between the rooms of the apartment or at home is not a luxury, but a fairly useful invention of our time. To ensure such a relationship, it is not at all necessary to acquire a home telephone station or DECT radio telephones.

If a simple negotiation device is required, then make a low frequency amplifier and pair of thin wires between rooms will not be much labor. In addition, apartment owners who disconnected from the wire broadcasting line can use "noodles", already laid in the walls of houses.

So, it remains only to make an electronic device that will ensure the transmission of sound signals on the wires as a basic element of such a device is very convenient to use the LM386 chip - universal low frequency amplifier.

This inexpensive microcircuit is widespread and allows you to produce low frequency amplifier with the required parameters at a minimum of external "strapping" elements.

The intercom proposed to the attention allows you to organize voice messaging (for example, to eat filed) or ensure a conversation in the so-called simplex mode, when one of the subscribers says, and the second listens, and vice versa.

Schematic scheme One of the two subscriber stations is shown in the first drawing. In the SC1 button shown in the Scheme, the device is de-energized.

When you press the SB1 button and hold it on the diagram, the supply voltage is fed 9 V. and the signal from an electre microphone VM1, reinforced by the DA1 microcircuit, is supplied to the second subscriber station (Fig. 2), the diagram of which is similar to those shown in Figure 1. Through Normally closed contact switch SB1 second station The signal comes to the VA1 loudspeaker.

After completing the transfer of the message or finishing the phrase in a conversation, the subscriber of the 1st station releases the SB1 button. If after that the button will click and hold the subscriber of the 2nd station, then the signal from it will hear the 1st subscriber.

To power each subscriber station, it is convenient to use small-sized transformer power supplies that are inserted into the AC network socket or the kroon type battery. Current consumption from the power supply occurs only when the SB1 button is pressed, and the dA1 chip current is not more than 10 mA. With the average volume of sound emitted by a loudspeaker having a winding resistance of 8 - 16 ohms, current. The amplifier consumed from the source 9 V. does not exceed 50 - 70 mA.

The optimal volume of the audio signal is set when setting up intercom. For this, the resistance resistance R2 is selected. At R2 \u003d 1.2, the gain coefficient for the voltage of the low frequency amplifier is about 50.

Reducing the resistance of this resistor, it is possible to increase the gain (maximum value 200 POSSIBLE at R2 \u003d 0), and increasing its resistance - reduce the amplification coefficient up to the minimum (20 when there is no chain R2-C3)

According to the materials of Jednoduchy Intercom - Domaci Telefon, published in Prakticka Elektronika magazine.

This electrical circuit It was collected and tested in laboratory conditions with connecting the communication channel to an external PBX. The switched virtual number for connecting the scheme was kindly provided by Mango Office.

Intercom - Scheme

Personal computer has long been long and deeply penetrated into our daily life, becoming the same necessary device as a TV. Many have changed the PC more than once, or they conducted its upgrade. Among other things, once bought inexpensive computer "speakers" (active AC), at some stage ceased to meet the user's demands or were replaced by more expensive with the quality of the sound of a good music center.

The same story happened to my "speakers" Genius SP-E120, - went to the far shelf, but came in handy when it took a simple intercom to one subscriber.

Figure 1 shows the active scheme acoustic system Genius SP-E120.
As can be seen from the figure, the scheme completely corresponds to the price of this equipment. Weak UMH on the chip TE2025.included in a typical scheme passive regulator Volume, and two speakers, one of which (SP1) in the main unit, and the second in the additional one. There, in the main unit there is both a fee with UNG, and a transformer power source. Additional block is almost empty - only SP2 speaker.

The sound quality is very mediocre, but to work as a negotiation device - the intercom, more than satisfactory.
The idea is to leave the main unit in the room, and an additional outward out. To add a pair of electrical microphones, and the blocking switch to eliminate the occurrence of self-excitation due to acoustic feedback.
The diagram of the negotiation device is shown in Figure 2.

The external unit is the second AC (which is empty), it is additionally necessary to install an electronic microphone M1. Connection with the main unit by means of a cable in which one lived is shielded (which means a signal from the microphone).

S1 - Switch "Reception / Perescha". It is only one, and is located only in the main unit. In the diagram, it is shown in the "Reception" position, that is, when we listen to the guest.

Power on the M1 microphone comes through the R1 resistor. Since the signal level at the outlet of the electretny microphone was not enough to submit to the input of UNG active speakers, there is an additional UNG on the VT1 transistor.

And so, the guest says, the signal from the microphone on the cable comes first on the UNG on VT1, and then on the left channel of the speaker. From the output of the left channel of the speakers via S1.2, the reinforced signal enters the speaker SP1 located in the main unit. And we hear the guest.

To answer the guest you need to press S1. Now our speaker SP1 is turned off, but the SP2 speaker is turned on, located in the external block.
The signal from the microphone M2 enters the preliminary UCH on VT2 and from it to the input of the right channel of the active speaker. From the output of the right channel AC, through S1.1, the reinforced signal comes on SP2 speaker located in the external block.

Guest hears that we are talking to him.

There is no calling device here, since there was already an ordinary apartment call, and before the start of the conversation, the guest presses its button.

I want to admit, initially planned to make a duplex system, since the amplifier stereo, but, alas, acoustic feedback It was possible to defeat only the S1 switch, which turned the system into simplex. But this is also not bad.
Sure, a similar device can be made from any inexpensive and no longer necessary active speaker for a personal computer.