Schematic scheme The PU is shown in Fig.2. The amplifier is assembled on the operating amplifier (OU). This middle accuracy with the built-in correction and protection of the output from the short circuit in the load.
Consider the work of the amplifier. The signal from the coal microphone VM1 amplitude of 30 ... 60 MV is amplified by the OU to the voltage of 1 V. The reinforcement coefficient of OU is set by the resistors R5 and R4 and is selected equal to 20 ... 30 (KU \u003d R5 / R4 \u003d 240K / 9.1K \u003d 26, 3).
These values \u200b\u200bof the gain of this OU and the amplitude of the input signal from the microphone were obtained from the experimental data and are optimal. The largest range is ensured by the maximum amplitude of the signal in the line at which there is no distortion. When the signal amplitude amplitude, 150 mV is supplied to the input of the signal at the outlet, the yield of 3.5V amplitude was obtained. With a further increase in the input signal, noticeable distortions began. The increase in the economy of the OU gain is more inexpedient, because the likelihood of the amplifier self-excitation increases.
The input signal level is set by the R1 resistor, which determines the current passing through the coal microphone. Reducing the resistance causes an increase in current through a coal microphone, and therefore raising input voltageremoved from the microphone and submitted to the OU.
If the MKE-3 Election Microphone is applied or an electrodynamic DAMSH, then the resistor R1 can exclude and use the inclusion scheme for the microphone used.
The voltage divider from resistors R2 and R3 allows you to provide unipolar nutrition. These resistors should be as possible by one nominal, otherwise the signal distortions at the OU output are not excluded. Their choice will be true if the voltage measured at the output 6 OU will be equal to half the supply voltage.
R6 resistor is a balance sheet required to provide duplex communication. It performs the function of the resistor RA or RV (Fig. 1).
The R7 resistor allows you to adjust the different resistance of the line and resistance of the telephone capsule, which means to achieve the elimination of the local effect when the signal from its microphone flies the signal coming into your phone from the interlocutor. If the lines and subscribers are several, it makes sense to make the R7 resistor variables to derive it for operational adjustment to the body.
To call another subscriber, it is enough to click on the S1 Call button. In this case, the feedback generated by the C2 capacitor turns the OU into the RC generator. The signal amplitude in the line at the call is from 3.5 to 4.5 V, the frequency of rectangular pulses is 1 kHz. The power allocated in the telephone champion of the interlocutor is at least 150 MW. This is enough to hear the challenge.

Fig. 2.

A little about the design and items PU. Printed circuit board (Fig. 3) For the amplifier, made of one-sided foil styling stalls with a thickness of 1.5 mm.
As a rapid resistor R7 in the amplifier used SP3-1B, it is possible to replace on SP-4 or variable resistor, for example, SP3-41. All other resistors - MLT-0.125 W. Oxyad condenser C1 - K56-12 (or K50-35); . C3 - K50-35; Capacitor C2 - MBM. Instead of a chip suitable, made in a rectangular plastic case. Switch S1 - PKN2-1B, switch S2 - P2K. Phone capsule - resistance 50 ... 60 ohms, microphone - coal, electrodynamic (Damsh), electret (MKE-3). Power supply - Croon Battery, "Corundum", "Nika".
Now about setting up. The first thing to do is to check the correctness of the conclusions of the DA1 chip (if you look at the legs on the side of the legs, then opposite the key-metal protrusion - there will be the first leg of the chip and then clockwise - the second, third, etc.). If you do not satisfy the quality of communication, you will have to deal with the PU more thoroughly. The sound frequency generator, the oscilloscope and the autometer will be required. The next one can recommend the next action algorithm. Check if there is a voltage equal to half of the supply voltage in the output 6. If necessary, set the specified mode more precise selection of resistors R2 and R3.
By connecting the oscilloscope first to the microphone, and then to the output of the PU, measure in each case the amplitude of the signal, talking before the microphone. If the signal from the microphone is significantly less than 50 mV, change the microphone. If there are no other microphones at hand, and the signal is no longer developing with any seabilities of R1, try to increase the gain coefficient to increase the resistor R5 resistance or reducing R4.
When observing the oscilloscope over the signal from the microphone, a variety of harmonics of different frequency and amplitude can be seen, it is difficult to determine and measure the true amplitude of the signal. Therefore, it is better to temporarily disable the microphone, and it is possible to file a sinusoidal signal with a frequency of 1000 Hz instead of it. Measure the amplitude of the signal at the input oscilloscope (left according to the output C1) and output (output 6) of the amplifier, determine the gain and, if it is less than 20, do the selection of resistors R4 and R5.

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 pre-amplifier On VT1 and the power amplifier collected 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. The pre-amplifier is assembled 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.

Intercom devices provide a telephone connection between the two subscribers. The call is carried out through the call available in the telephone. In such intercoms, you can use telephone sets that have only a handset, a call and a lever switch.

Telephones E1 and E2 (Fig. 1) are connected by a three-wire line into which the variable and constant voltage is supplied. A variable voltage is removed from the winding of the II network transformer T1, constant - with a parametric voltage stabilizer (R1, VD2, CD of a two-speech rectifier (VD1) powered by a transformer III winding.

If the first subscriber (he has an E1 telephone) wants to call a second subscriber, it must press the SB1 switch button. Wherein aC voltage From the winding of the II transformer is fed to the E2 telephone, and the call is ringing. With the tubes of both telephone devices source constant voltage It turns on in series with devices - you can talk. The second subscriber to call the first presses the SB2 switch button. The rectifier diode bridge VD1 can be any of the KC402 series, CC405, KC407. It can be collected on four diodes of the series D7, D9, D220, D223, D311. Condensatory C1 - K50-6, K50-16, K50-24. Push-button switches - km-1, p2k, power switch - TW2-1 toggle switch. The network transformer is made on the ribbon magnetic circuit bowed 16x25. Winding I contains 2200 turns of the wires of the PEV-2 0.08, winding II - 400 turns of PEV-2 0.10, winding III - 100 turns of PEV-2 0.19.

Telephone devices can be TA-68, TAN-66, TAN-70. In the same case, if devices with defective dialer are used, the conductor can be turned off from the dialer and connect them to the lever switch so that when the tube is lowered to the line, it was connected through a capacitance with a capacity of 1 μF (it is in the device) call, and when the tube is raised ? Seriously connected microphone and phone tube.

The transformer and parts of the rectifier are mounted in the E1 apparatus housing. The power switch is installed on its back wall, and through the hole in the wall, the power cord is displayed with a fork at the end. Switches are installed on telephone housings. For the line, a single-core or stranded telephone or mounted wire with a residential diameter of HS is less than 0.5 mm at large distances (up to 1 km) and Ns less than 0.2 mm - at small (up to 200 m). The diameter of the wire is determined mainly by considerations of its mechanical strength.

Despite its simplicity, such a negotiation device has a drawback: the communication line contains three wires. By some complication of the device, you can reduce the number of wires in line to two, as is the case in urban telephone networks.

Views of Commax Membering Devices

• Hands-link devices: Central and subscriber remotes in desktop and wall design, with a remote or built-in microphone. Depending on the real needs in the catalog, you can pick up as a relative simple bilateral system ("cashier-client") and complexes on 10, 20, 30 or even 50 stations.
• COMMAX wireless negotiations are solutions that provide maximum flexibility and mobility of execution, as well as ease of installation on any object. In the assortment of the online store there is both desktop devices Hands-Free and wall solutions with a tube or without it. It is worth noting that most of these systems are easily scalable and can combine up to 100 subscribers without the need for additional configuration and installation when expanding. On the other hand, inexpensive duplex devices are always popular, which is convenient to use as an audio device.
• Wired intercoms with a tube - a traditional solution that is distinguished by the available price and ease of use. In stock There are simple sets of two tubes and systems to a larger number of subscribers with a push-button panel, which allows you to quickly contact any other point.

Such a variety allows you to choose a better solution for any object. Commax's most widely broadly negotiation devices are used to equip:

• apartment and private residential buildings (as a traditional audio intercom);
• large enterprises (for communication between divisions, shops, departments, etc.);
• shopping and shopping and entertainment institutions, supermarkets, shops (for speakerphone and ads in the trading room, for communication with the warehouse and other).

Why Commax?

To date, Commax (South Korea), founded in 1968, is one of the recognized world leaders in the production of intercoms, intercom and other electronic equipment for video surveillance and access control. Brand products are sold in more than 100 countries, and in most of them Commax plays a leading role in its segment of the market. Intercoms of this brand are distinguished by thoughtful functionality, certified in UL and TUV systems, and reliability of execution is confirmed by many years of use.

Commax Intercoms in the Rossi online store catalog

Catalog "Rossi" is an opportunity to buy Commax negotiations in Moscow with the possibility of choosing the best solutions among dozens of unique options. On the page of the online store and during consultation by phone you can order kits and additional system elements in any quantity, in strict accordance with the features of the object and the task. Call now!