Neighbors guard the apartment. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Neighbors guard the apartment. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Safety and security

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To protect themselves from burglaries, one part of the population installs steel doors, solving this problem alone. Another, not numerous, for a certain monthly fee, uses the alarm system installed in the apartment by private security. The latter is far from always possible, because, among other things, it requires a telephone in the apartment. The author of this article offers another way to protect apartments - association with neighbors based on an electronic security device.

It should be emphasized that this association can only be voluntary and that it does not entail any legal obligations. Neighbors united to protect their apartments must be prepared for certain inconveniences. In addition, false alarms of the system are quite possible (alas, even at night), including due to equipment failures or due to elementary forgetfulness of a neighbor.

The security alarm unites four apartments in which one identical device is installed. Suppose a neighbor (conditionally - number 2), leaving the apartment, switches the device to the "Watch" mode. After closing the front door, it will automatically go into standby mode, which can be in a long time. When the neighbor (2) returns and opens the front door, he must switch the device to the "Clear" mode within 30 seconds. If this is not done, the device will give an alarm to other neighboring devices (1, 3 and 4). All devices have LED and sound indication. Neighbors, having heard the signal, will determine in which apartment the alarm went off, and they can take action together.

It happens that they call the apartment at a time when you are not expecting anyone. You can turn the device into "Guest" mode and open the front door. The device starts timing about four minutes to signal. This time is enough to find out the identity and purpose of the guest's arrival and, if necessary, have time to turn off the mode during this time.

Apartments can be located not only on the same floor, but also on different floors. The length of the connecting wire between the apartments is up to 20 m. The operability of the security alarm with a longer wire has not been tested.

A diagram of one of the devices is shown in fig. one.

(click to enlarge)

Trigger DD1.1 eliminates the bounce of the contacts of the switch SA1. When switching SA1 to the lower position according to the "Watch" position, a high level will appear at the information input D of the trigger DD1.2 (pin 5). Trigger DD3.1 eliminates the bounce of the contacts of the reed switch SF1 installed in the door unit.

When the front door is opened for the first time (after switching SA1), the reed switch SF1 will switch to the upper position according to the scheme, the trigger DD3.1 will go to the zero state (high level at the inverse output). Trigger DD1.2 will change its state to single. Leaving the apartment, the owner closes the door, the reed switch SF1 switches to its original position and the trigger DD2.1 goes into a single state. The unit has been armed.

If the door was opened a second time, it is necessary to switch SA1, canceling the "Watch" mode. Otherwise, a high level appears at the output of the trigger DD2.2, which allows the passage of second pulses from the generator made on the elements DD7.1 and DD7.2 to the counter DD8. When a high level appears at the output 25 of the counter DD8 (pin 4), the trigger DD6.2 switches and the HL2 LED lights up.

From the output of the DD10.3 element, a high level is supplied to the terminals of 4 XZ-X5 connectors and to one of the inputs of the DD4.3 element. If the switch SA3 is in the lower "Signal" position according to the scheme, the audio frequency signal from the generator, made on the elements DD7.3 and DD7.4, comes through the elements DD9.1, DD12.2, DD12.4 and the amplifying stage on transistors VT1 , VT2 to the X6 connector and then to the dynamic head. When SA3 is in the upper position, the sound signal will not pass. Which of these two modes is better is up to the owner to decide.

When you press the apartment call button SB1 "Call", regardless of the position of SA3, the sound signal will go to the dynamic head, but at a frequency four times lower (two octaves). Frequency divides the frequency divider on triggers DD11 -1 and DD11.2. This is done in order not to confuse a bell signal with an emergency signal.

When switching SA2 to the lower position according to the scheme, the "Guest" mode is activated. Trigger DD3.2 goes into a single state, and second pulses begin to arrive at the counter DD5. LED HL1 starts blinking. When a high level appears at the output 28 of the DD5 counter (pin 12) (after about four minutes), the DD6.1 trigger will switch and its inverse output will be low. The HL2 LED will turn on, signaling the operation of the emergency system. As in the previous case, a high level appears at the pins of 4 XZ-X5 connectors.

The devices are interconnected by a double-insulated flat four-wire telephone cable. The wiring of the cable connectors is shown in fig. 2.

Neighbors guard the apartment

On fig. 3 shows a connection diagram of neighbor blocks.

(click to enlarge)

Here, each connecting line corresponds to a four-wire cable. If the security alarm is triggered in one of the apartments, a high level will appear on terminals 1 of one of the X5-X10.4 connectors of all other apartments. For all neighbors, the signal is inverted by one of the inverters DD10.6-DD1 (see Fig. 3). One of the HL5-HL9 LEDs will turn on, signaling a problem with a neighbor. A low level at one of the inputs 10, 11 or 9.2 of the DD9.1 chip will allow the audio frequency signal to pass through the DD3 element and beyond, regardless of the setting of the SAXNUMX switch on their blocks. A break in the wire connecting the apartments will cause the signal to turn on in all apartments.

The devices are powered by 220 V. In the event of a power outage, the GB1 "Krona" battery is automatically connected. The SB2 button is used to check the health of the battery without removing it from the case. If the HL6 LED lights up when you press the button, then the battery is good.

The power transformer T1 - TPK-2, which has two secondary windings of 8 V each, the winding current is 0,125 A. The socket parts of the X1-X6 connectors are TJ4-4P4C, they are used in imported telephones to connect the handset. The mating part of the connector is TP4R4C. Dynamic head of any power 3 W with a voice coil resistance of 4 ohms.

The blocks of the device are assembled on identical printed circuit boards made of double-sided fiberglass (Fig. 4). Pin 13 of the DD2 chip must be connected with a wire jumper on the printed circuit board to pin 6 of the DD4 chip.

(click to enlarge)

The SF1 reed switch is installed in the door frame, a small magnet is installed at the end of the door. When the door is closed, the magnet must be at a minimum distance from the reed switch and influence its moving contact. Switch SA1-SA3, button SB2 and LEDs HL1-HL6 are located on the front panel of the device.

Author: A.Fadeev, Moscow

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