Now almost any entrance of multi-storey buildings, office buildings is equipped with an intercom. This is done in order to prevent unauthorized entry into the territory, access to which is by definition limited. What is this device, how exactly is it arranged?
Device and principle of operation
The intercom is an electromagnetic locking device with the ability to remotely control the opening-closing process from the remotes (tubes) located in apartments or offices. The system is installed on the driveway and protects the building from unwanted intrusion.
Depending on the system for connecting apartments to the intercom device, digital and coordinate devices are distinguished.
With a coordinate switching system, a separate cable goes to each apartment from the intercom, while with a digital one, there is only one connecting cable. It would seem that digital intercoms should be cheaper, however, in fact, everything is exactly the opposite - their cost is almost 3 times higher than that of coordinate systems. But it is believed that this pays off with the higher reliability and security of such a communication system.
By the type of communication, intercoms are divided into audio and video devices. From the name it is clear that video intercoms have a screen on which the identity of the caller is displayed, and audio devices provide only voice communication. Naturally, devices that transmit video images provide a higher level of protection, but do not forget about the price aspect - they are much more expensive than voice intercoms and, as a result, are much less common. Usually, video devices are installed at the gates of large private properties.
Connection to digital intercoms
How to properly connect a digital intercom tube in an apartment? This is not difficult at all, provided you follow a few rules. The subscriber unit of the intercom system consists of a panel and a tube. The panel is usually installed on the side of the front door, the place where the tube is installed, if desired, can be anywhere, the only thing is that you will need to run the cable from the panel there. The internal structure of the intercom tube is almost no different from the telephone one - there is also a microphone with a speaker and a microcircuit. The driveway unlock button can be located both on the handset and on the wall panel.
On the rear side of the panel part of the device there are two terminals with polarity markings ("+" and "-"). You need to connect a two-wire line to them. It is important not to reverse the polarity of the wires during installation - otherwise the system will not function.
To facilitate this process, wires of the same polarity usually come in the same color.
The initial installation of the intercom system is always carried out by professionals, independent replacement comes down to buying a new intercom, actually replacing and connecting the wires. Before buying a handset, check the type of your intercom. Different models are available for digital and coordinate systems. The diagram for connecting the handset to a digital intercom has its own characteristics. During the installation process, you need to dial the apartment number. This is done like this.
- Open the case of the uniphone carefully. You will see that the microcircuit has paired pins numbered 1-2-4-8
- Using special jumpers, connect the pairs in parallel so that the sum of their numbers equals the number of your apartment. For apartment number 15, for example, you need to close the first four pairs.
Please note that malfunctions with one apartment intercom can affect the functioning of the entire system, this is the main disadvantage of such systems. In order to localize a fault within one floor, floor controllers can be additionally integrated into the system.
Installation on the device of the coordinate matrix type
Connecting the handset to an analog (coordinate matrix) device is different from the same operation with a digital device. An analog intercom system works on the principle of a telephone exchange - a switchboard carries out reception, analysis and connection with the desired subscriber. Subscribers are usually connected to the system in parallel.
There are 2 special buses designed to connect the intercom with the switch. On the first bus, contacts (D0-D9) are responsible for tens in apartment numbers, on the second (E0-E9) - for units. Connect the wire from the terminal with the plus sign to the contact responsible for the ten in your room (for apartment No. 87 - 8), the wire from the negative terminal is connected to the single contact (in our example, 7).
If your entrance has more than 100 apartments, the intercom model must correspond to this number (there must also be a third bus responsible for hundreds in apartment numbers). The principle is the same.
In some cases, when installing an intercom system, the customizers reprogram the panel by shifting the numbers by a certain amount. This action is performed, for example, if it is impossible to connect hundredth numbers. In such a situation, you cannot connect the tube with your own hands, you will have to call the specialist who set up your system. Switches are usually installed on each floor in distribution boards and connected to each other in a parallel circuit.
It is also possible to install one switching device for the entire entrance, but in such a situation, additional tens of meters of cable will be required in order to consistently connect apartments on the upper floors. If, when connecting at least one subscriber intercom to the analogue entrance system, the polarity of the wire connection is violated, this may affect the functioning of all system devices, as is the case with digital intercom.
Possible malfunctions
During the operation of the intercom system, various malfunctions may occur :
- mechanical damage to the tube;
- when picking up the handset, the signal continues to sound;
- failure of the lock unlocking button;
- the caller's voice is hard to hear;
- if you press the door open button, the call is canceled.
In the first case, it is easier to replace the damaged part (tube), because they are not so expensive. The main thing is to choose the right intercom for your model of the intercom system. In situations where the call signal does not turn off when you pick up the handset, there is no communication with the caller and there is no reaction to pressing the lock control button - look for a breakdown in the off-hook switch. It can be repaired or replaced with your own hands, however, it is still recommended to entrust it to professionals, especially if you have not done anything like this before. This procedure requires some experience and appropriate tools.
If you have to press the electric button several times to open the lock, the microswitch is to blame. It is not difficult to change this part yourself, even if it is located on the intercom handset. It is enough to carefully unsolder the contacts of the defective part, remove it and solder a new one. If the visitor is hard to hear, it is the speaker or the microphone. In some models, such a malfunction may be caused by clogging of the "Balance" resistor installed on the doorphone board .
In the latter case, you can independently try to twist the resistor lever, in most cases, audibility is restored.
Unauthorized disconnection of a call when unlocking the lock can be caused by an interruption in the electrical circuit coming from the speaker. In this case, carefully inspect all the cable connection points - both on the panel and on the intercom. Switch off the appliance first, of course. If there is a break somewhere, you need to replace the wire or solder the contacts of the wire and terminals. Summing up, we can say the following: in many cases, you can replace a damaged tube of both digital and coordinate-matrix intercoms yourself, this is a fairly simple action. Only in some cases is it worth calling the wizards of your intercom system.
For information on how to connect different intercom handsets, see the next video.