We make a security alarm with our own hands. Schemes of three options for homemade alarms (CD4093) Schemes of homemade security alarms on microcircuits

A distinctive feature of this circuit is that it is built on the simplest element base - a microcircuit with six K561ЛH2 inverters and an operational amplifier in the sensor system. With all this, the alarm system provides a full range of functions for devices made on more microcircuits The car alarm circuit allows for two options: with a delay in turning on the sound signal to turn off the alarm from the passenger compartment, and an option with immediate activation of the signal after the sensor is triggered, and external activation of the delay by the owner using a reed switch and a magnet key fob.

The car alarm system consists of three nodes:

A system of two sensors - a body vibration sensor made on the basis of a microammeter connected between the inputs of the voltage comparator, and contact sensor, the role of which is played by the car door switch.
- a logic circuit on RC circuits, consisting of a pulse shaper, a one-shot, a multivibrator,
- an actuator based on electronic key on a composite transistor and a standard car horn relay.

The algorithm of work is as follows. The security device is assembled in a small plastic box, which is connected to the vehicle systems using a cable with a standard five-pin connector from audio equipment.

Before leaving the cabin, the owner connects the security unit using a cable to a socket installed under the dashboard of the car and places the device body on the dashboard (in the version with a reed switch) or turns on the power using a hidden switch (in the option with a delay switch, while the housing device installed in dashboard cars).

After turning on the power, the alarm does not go off for 30-40 seconds. This time is needed for the owner to leave the cabin, close the doors, etc.

After this time, the watchman switches to driving mode. When a signal is received from one of the sensors (body vibrations from attempts to break into the door, hood, trunk, removing a wheel, closing contacts when opening the door), the guard, in the version with a delay, works out a delay of 5 seconds to turn it off by the owner, in the version with a reed switch, without delay, and then plays an intermittent beep that lasts about 20 seconds. The circuit then returns to its original standby mode.

To turn off the alarm with a reed switch, the car owner must first bring the key fob magnet to the reed switch, located, for example, behind the windshield in the trim area, and then open the door and turn off the alarm by unplugging the cable from the connector.

Schematic diagram is shown in Figure 1. When the circuit is connected to a power source, capacitor C4 begins to charge through resistor R4, as a result, a logical zero is supplied to the input D1.5 through the diode VD4, which fixes the multivibrator on D1.5 D1.6 in the logical zero position at the output. After charging C4, VD4 ceases to affect the operation of the multivibrator. The device goes into searching mode.

When the car body oscillates, the magnetic system of an inertial sensor based on a microammeter produces an alternating EMF that occurs between the inputs of D2 and is amplified by this comparator and is converted into negative pulses. One pulse is enough to trigger.

When the door is opened, the contacts of the door switch are additionally closed and the first contact of connector XS1 is connected to ground, as a result, through VD1 a negative level or through VD2 a negative pulse is sent to the driver on two elements D1.1 and D1.2. Negative
a pulse from output D1.2 through diode VD3 discharges capacitor C2 of the monostable on elements D1.3 D1.4.

At the same time, a high level appears at its output, which, after the sensor stops operating (the door is closed, the car stops rocking), turns into a positive pulse lasting about 20 seconds (if the door is open or the car continues to rock, the pulse is proportionally longer).

Fig.2
This pulse, in a delayed circuit, is supplied through the RC circuit R3C3 to the cathode of the diode VD6 and the multivibrator D1.5 D1.6 leaves the fixed position and begins to generate positive pulses that are supplied to the transistor switch on VT1 VT2, which controls the sound signal turn (in fact, the key turns on parallel to the car horn button).

In the circuit with a reed switch (Figure 2), resistor R3 and capacitor C3 are removed, and the cathode of the diode VD6 is connected directly to the output of the monovibrator, it is clear that in this case the multivibrator D1.5 D1.6 is turned on immediately after the sensor is triggered. The reed switch is connected in parallel with capacitor C4, which creates a time delay after turning on the power.

It turns out that when a magnet is brought close to it, its contacts close C4 and discharge it; a logical zero is sent to the cathode VD4, as during the holding period after switching on. It turns out as if the alarm has just been turned on and there are 30-40 seconds to close the doors and exit, which can be used to open the doors and disconnect the HS1 connector.

Fig.3
The entire device is mounted on one printed circuit board, wiring diagram which is shown in Figure 3 c life size(corresponding to the natural value of the fee).

The board is placed in a plastic case on the lid of which an LED is attached.

The inertial sensor is made from an M470 type indicator from a cassette recorder. You need to separate the halves of the case and remove the cover covering the scale, then attach a flat weight, such as a washer, to the arrow so that it does not touch the scale and glue the case back together.

Self-locking security alarm device

A simple and reliable security alarm device with self-locking is shown in the schematic diagram (Fig. 1).

Security alarm with self-locking photo relay

Fig 1.

The device is used as a light detector: the HL1 LED lights up if the photosensor - photoresistor PR1 does not get natural or electric light. In practice, this electronic unit will help in monitoring the security zone of a house or garden.

While photoresistor PR1 is illuminated, its resistance remains constant electric current is small, and the voltage drop across it is not enough to unlock the thyristor VS1.

If the light flow acting on the photosensor is interrupted, the resistance PR1 increases to 1...5 MOhm, then capacitor C1 begins to charge from the power source.

This causes the thyristor VS1 to turn on and the LED HL1 to turn on. Button S1 is designed to return the device to its original state.

Instead of the HL1 LED (and the current-limiting resistor R2 connected in series with it), you can use a low-power electromagnetic relay such as RES 10 (passport 302, 303), RES 15 (passport 003) or similar with an operating current of 15...30 mA. As the power supply voltage increases, the relay current consumption increases.

Instead of the KU101A thyristor, you can use any thyristors of the KU101 series. Photosensor PR1 consists of two parallel-connected (for better sensitivity there is no need for an additional signal amplifier) ​​SFZ-1 photoresistors.

Kashkarov A.P.

Sensory watchdog

Fig.2

The sensor device (Fig. 2) can be used, for example, in a watchdog device for front door. To do this, metal parts of the door handle are used as one sensor, and the second is secretly installed in doorway. Then, while simultaneously touching door handle and to the “secret” sensor, relay K1 will operate and disable the lock’s safety mechanism. When only one of the sensors is touched, the lock remains locked.

A variable resistor is used to adjust the sensitivity of the amplifier and control the device using two sensors E1 and E2.

Yantsev V.

Combination lock on a chip

In the electronic combination lock circuit (Fig. 3) they work D - triggers of the K155TM2 microcircuit, two transistors and a thyristortraction electromagnet control.

Fig.3

An electromagnet can operate and move the door lock bolt only when the thyristor opens and current flows through the electromagnet winding. But in order for the thyristor to open, both transistors connected to each other in series must be in the open state, which can only happen if voltages are simultaneously applied to the bases of the transistors high level. In all other cases, the transistors will be closed, the electromagnet will be de-energized and the door will not be able to be opened.

In the initial state, the contacts of all buttons and switches S.A. 1 "Reset" are open. The lock code is three-digit, for example 123. This means that you need to press the coded button first SB 1, second - button SB 2, third - SB 3. If the order is different or you press any of the uncoded buttons ( SB 4-SB 10) the lock will not work.

Switch SA 1 “Reset” consists of two contacts, which are mounted on the door in a normally open state. When the door opens, they close, the trigger of the microcircuit goes to the zero state. When closing the door contacts S.A. 1 are opened again and the electronic part of the combination lock is in the original, standby mode of operation.

To change the lock code, you just need to change the order of connecting to the buttons the conductors going to them from the trigger inputs and the corresponding resistors R 1 - R 3.

The electronic part of the lock can be powered from any full-wave rectifier with an output voltage of 5V. The traction electromagnet must be designed to operate at a mains voltage of 127 V, i.e. almost half as much as 220 V. This is explained by the fact that current flows through the thyristor, which operates in the open state as a diode, and the electromagnet winding only during one half-cycle of the mains voltage.

When connecting the device to the network, you must ensure that neutral wire connected to the common “grounded” conductor of the power supply circuit of the electronic part of the lock.

Borisov V.G.

Security alarm LED simulation circuit

The problem of theft in apartments and buildings is the most pressing in our time, and many wealthy people equip their apartments with various systems alarms that have access to the police or some organization involved in the protection of objects. In such apartments, various sensors are installed on doors and windows, some of which have indicator LEDs that flash in standby mode.

Often, only the presence of such sensors makes it clear to a not very experienced thief, of whom the majority are in the criminal world (an experienced one will be able to turn off a real alarm), that it is better to look for another object to steal. Thus, you can protect yourself from the attacks of criminals even only by creating the appearance of having security.

To create the appearance of security, you can install plastic boxes on the windows or on the front door, each of which has two LEDs different colors, which flash alternately. The presence of these harmless items, along with strong locks and a metalized front door, as noted above, can help prevent theft, Fig. 4.

Fig.4

A multivibrator assembled on a K561LA7 microcircuit, at the output of which two LEDs are switched on through inverters, so that they blink alternately, one lights up when the pulses at the multivibrator output fall, and the second lights up when the pulse rises. The blinking frequency of the LEDs depends on the parameters of the RC circuit R1C2. If necessary, the blinking frequency can be set by selecting the values ​​of R1 or C2. The cascades on inverters D1.3 and D1.4 act as power amplifiers for the output signals of the multivibrator on D1.1 and D1.2 and provide alternating operation of the LEDs.

The flasher is powered directly from a 220V power supply without the use of an intermediate transformer. The power supply is simplified, consists of capacitor C1, reactance which extinguishes the excess voltage, and a rectifier-stabilizer on diode VD1 and zener diode VD2.

Laser security device

The device shown in Figure 5 can be used to protect your property indoors or outdoors. It is possible to protect a larger area, such as the perimeter of your property.

Fig.5

The circuit is based on a laser pointer as a light source. Nutrition laser pointer usually consists of 3 hour batteries, which is not very practical due to the short battery life. Therefore, it would be better to use a stationary power supply with a limiting resistor. The current should be limited to 40 mA.

To prevent false alarm The circuit provides a time delay. If it is necessary to increase the delay, this can be done by increasing the capacitance of capacitor C1 or increasing the value of variable resistors R2 and R3. The reset button must have normally closed contacts. Timer NE555 or its domestic analogue - KR1006VI1.

To prevent direct sun rays the phototransistor must be placed in a tube with a diameter of 3 cm and a length of 30 cm. The end must be covered with glass to protect it from mice and birds. Inner surface the tubes must be painted black. You must use a siren from a car alarm as a sound signal.

Fire smoke detector

The smoke sensor monitors the degree of air transparency in the room in which it is installed, and in the event of smoke (air transparency decreases), a logical zero level is set at its output. The circuit diagram is shown in Figure 6.

Fig.6

The sensor is based on an optical pair consisting of an LED VD 1 and photodiode VD 2. The photodiode and LED are located at a distance of about 50 mm from each other and are directed so that there is a optical communication.

As long as there is no smoke, the optical coupling is high and the reverse resistance of the photodiode is low, significantly lower than the resistance of the resistor R 2. Therefore, at the connection point VD 2 and R 2 the voltage corresponds to the logical one level. Schmitt trigger on D 1 is in the single state, and the output of the sensor will be a logical one.

When smoke occurs, air transparency deteriorates and the optical connection between VD 1 and VD 2 weakens. As a result, the photodiode resistance VD 2 increases, and at a certain moment the voltage at the connection point VD 2 and R 2 becomes below the logic zero threshold. Schmitt trigger on D 1 takes the zero position and a low logical level is set at the sensor output, which serves as a fire danger signal.

The circuit uses FD-320 (from systems remote control TV type USST). It can be replaced with another similar one, for example FD-611. The LED can be of almost any visible radiation spectrum. The sensor has a box-shaped housing with a rectangular hole at the bottom for the passage of smoke. The box is made in such a way (it has a partition at half the height of the box) so that direct sunlight (or light from lighting fixtures) cannot reach the sensor through this hole.

Adjusting the resistor R 2 it is necessary to ensure that the sensor is triggered (a threshold of 0 is set at the output) when placed between VD 1 and VD 2 sheets of fax paper, both in complete darkness and in normal daylight. If necessary, select the denomination R1.

The final adjustment must be carried out in the smoke, always outdoors and observing all fire safety rules.

During the setup process, it is necessary to ensure that the sensor is not exposed to direct sunlight (or light from lighting lamps).

The sensor must be powered by a stable voltage.

Lyzhin R.

"Radio constructor

2003, No. 1"

Sensor - “someone is behind the door”

This circuit can serve as a kind of security device and an automatic bell button, Fig. 7.

Fig.7

The essence of the circuit is that it reacts to a decrease in the illumination of a certain area of ​​your front door. If your entrance is “civilized”, then the lamp is on staircase usually correct. The photo sensor is located on your front door so that when a person stands in front of it, he blocks the light from the lamp lamp with his body. The sensor responds to this, briefly closing the alarm button.

Capacitor C3 is needed to limit the time the contacts P1 are closed. F 1 - phototransistor from an old ball mouse. Setting sensitivity - variable resistor R 1. Relay KUTS-1, - a power relay from the remote control of an old TV.

Snegirev I.

Electronic combination lock

The schematic diagram of a simple electronic combination lock is shown in Fig. 8.

Fig.8

Keyboard of ten buttons ( S 1- S 2). The code number can consist of several digits, in this case, three. The buttons on the keyboard are labeled from “0” to “9”. To set the code, you need to select any three buttons from them and connect them in series - these will be the buttons S 8, S 9, S 10. And the remaining buttons need to be connected in parallel ( S1-S7).

As long as no button is pressed, the base VT 3 no voltage, transistors VT 3-VT 4 are closed and relay K1 is turned off. Capacitor C1 is discharged and the voltage at the base VT 1 is also not enough, so the composite transistor VT 1- VT 2 is closed and the voltage on its collector is high.

To turn on relay K1 you need to dial the correct code. To do this, you need to simultaneously press three code number buttons - in this case S 8, S 9, S 10. If the code is entered correctly (only these three buttons are pressed), then through them to the base VT 3 voltage will come from the collector VT 2. Transistors VT3-VT4 will open and relay K1 will turn on.

If the code is typed with three digits, but incorrectly, then if at least one digit is incorrect, then, firstly, the circuit S 8 - S 10 will not close to the base VT 3, no voltage will be supplied. Secondly, since one (or more) of the buttons will be pressed S 1 - S 7, then capacitor C1 will charge, the voltage on it will become high and the transistors VT 1- VT 2 will open. The voltage at their collector will drop. Therefore, even if you press all the buttons at the same time, including S 8 - S 10, the lock will not open because the voltage on the collector VT 1- VT 2 will not be enough to open VT 3- VT 4.

Moreover, if you try to find the code by trying different combinations, this task will be greatly complicated by the fact that after each button press S 1 - S 7 capacitor C1 is charged and holds the transistors VT 1- VT 2 open for a few seconds. And at this time, even a correctly guessed code will not be accepted as correct.

Thus, using capacitor C1 and a composite transistor VT 1- VT 2, protection against code selection and opening is provided by simultaneously pressing all buttons.

All buttons must be non-latching. Special buttons for intercoms with numbers are best suited. But any closing ones without fixation will do. The code to which the lock should respond is set as follows: select the numbers that make up the code number, for example, “480” and connect the buttons with such numbers in series. And then, connect them like S 8, S 9, S 10 on the diagram. Connect the remaining buttons in parallel and connect them as buttons S 1- S 7 in the diagram.

Capacitor C1 can be from 4.7 µF to 22 µF. How long the circuit waits after an incorrect code is entered depends on its capacity. The capacitance of capacitor C2 can be from 47 µF to 2000 µF.

The KD522 diode can be replaced with almost any diode, for example KD521, KD209, KD103, etc. The diode in the circuit must be connected in reverse polarity (cathode to the power supply plus).

Relay type WJ 118-1 C with a 12V winding. The board is made specifically for this relay.

The lock is powered by a constant voltage of 12V. Relay contacts WJ 118-1 C can switch as a low-voltage load (at a voltage of 12V with a current of up to 20A). And power supply from the mains (220V, with a current of up to 5A).

Lyzhin R.

Electronic lock with “USB” key

Nowadays they are increasingly used electronic locks with digital keys - tablets. There are also systems in which the key is USB flash drive.

Fig.9

Both represent a block of memory that contains a digital recording file. These systems are, of course, very reliable, but like everything related to computers, they are susceptible to computer hacking methods. This key, consists of a connector with a soldered resistor of a certain value and is located in the housing of the faulty USB - flash drives. Figure 9 shows the diagram simple lock, reacting the resistance of the key resistor (four-pin connector X1).

The circuit uses a RES10 relay (passport RS4 524.302). Structurally, the XP1 key is a connector to which a resistor is soldered. Transistor VT 1 can be of any type. Setting it up involves selecting values R 1 and R 2 at which relay K1 is activated.

Schemes of simple security devices

Security devices with intermittent light and sound alarms are shown in Fig. 10 and 11.

Fig.10

In the first option in Fig. 8, the security alarm loop B1 is connected parallel to the emitter-base transition of the transistor VT 1. If the loop is in good condition, the transistor VT 1 is closed, the device consumes a current of no more than 20 μA from the power source. If the loop is broken, the transistor pulse generator VT 1 and VT 2 will begin to synchronously produce short ringing bursts of sound ( B.F. 1) and bright flashes of light ( HL 1).

Average current consumed by the device in mode alarm system, is 2 mA at a repetition rate of light and sound transmissions of 1...3 Hz. Resistor R 2 determines the repetition rate of light and sound messages - from continuous sound and glow to fractions of Hz.

Fig.11

The device in Fig. 10 uses a piezoceramic transducer as a sensor BQ 1 (ZPZ type emitter). If it is glued to the surface of glass or other smooth surface, then a light tap on the glass will trigger the light and sound alarm - followed by a short light and sound signal. Potentiometer R3 adjust the device's response threshold.

The idea of ​​this development does not belong to the author of this article, I only repeated and slightly improved the scheme. In general, we take one that responds to door openings (cost 40-50 rubles). In normal mode, it reacts to the opening of the door, but it can easily be converted into a loop one.

This alarm consists of electronic unit with siren and magnet. In standby mode, the magnet closes the reed switch; when the magnet is removed, a sound signal is heard. In general, in many blocks there is not a reed switch, but simply a pair of open contacts (“Chinacon”, as the author of this device called this group of contacts). "Chinacons" quickly either stick or the contact surface oxidizes. So, I strongly recommend disassembling each block and installing normal reed switches. “Kitaikon”, I can’t show you, I threw it away a long time ago as unnecessary and put in its place an ordinary normally open reed switch. In order to equip this alarm with a cable, we drill holes at the ends of the block for clamps for the cable. M4x10 screws were used as clamps. The nut holds the screw in place, and a clamp is screwed on top of it, which presses the wire. If there is no special clamp, you can use a regular M4 nut, but naturally, it is not so convenient to unscrew it without tools; you can also use a wing nut.

We connect the clamps to the reed switch terminals, that is, the cable is connected in parallel to the reed switch. As a train Any will do thin copper wire, which is easy to break. Such a wire can be found in any network transformer. Only it is usually covered with varnish insulation, which must be removed from the ends of the wire. So, the device is ready.

With a short piece of wire, such a security alarm unit can be used as a pocket siren. The alarm also works with a cable length of at least 5 meters. Also, the alarm does not lose its functionality if instead of a cable you connect a resistor with a resistance of 510 Ohms, the same resistance has a piece of wire PEV 0.1 (diameter 0.1 mm) with a length of 230 m. This cable is enough to surround a perimeter zone with a radius of 35 m. Which is quite enough to create a security perimeter around the tent. Thank you for your attention, you were Lekomtsev D.G.

The article provides a diagram of a simple security alarm, a description of the operation, and resident software (firmware). The device is not difficult to assemble with your own hands. All the information necessary for this is in the article.

General description of the device.

The security alarm system is assembled on a PIC controller PIC12F629. This is a microcontroller with 8 pins and a price of only $0.5. Despite the simplicity and low cost, the device provides control of two standard security alarm loops. The alarm can be used to protect enough large objects. The device is controlled by a remote control with two buttons and one LED.

Our company has moved to a new building. An old security alarm remained from the previous owners. It consisted of an iron box with red LEDs and a siren above the front door and a broken electronic unit.

I installed a small circuit board in the alarm box and turned this junk into a modern, reliable burglar alarm. IN this moment it is used to guard a two-story building with a total area of ​​250 m2.

So, the alarm provides:

• Monitoring of two standard security loops with measurement of their resistance and digital filtering of signals.
• Remote control (two buttons and one LED):
  • turning on the alarm;
  • disabling the alarm via secret code
  • setting a secret code (the code is stored in the internal non-volatile memory of the controller);
  • indication of operating mode by the remote control LED.
• The device generates time delays necessary for dialing a secret code, closing room doors, etc.
• When an alarm is triggered, the device turns on the sounder (siren).
• The operating mode of the device is also displayed by an external light source.

The block diagram of a security alarm looks like this.

The following are connected to the main security alarm unit:

• 2 security loops with
  • NC – normally closed sensors;
  • NR - normally open sensors;
  • Rok – terminal resistors.
• External sound notification and mode indication unit.
• Backup power supply.
• Power supply 12 V.

Security alarm loops and sensor connections.

To monitor sensors (detectors), the device uses standard security loops. The resistance of the loops is controlled. If the circuit resistance is greater than the upper or less than the lower threshold, then an alarm signal is generated. The normal resistance of the loop is equal to the terminal resistor (2 kOhm). Thus, if an attacker breaks the wires of the loops or short-circuits them, the alarm will go off. This way to disable security sensors will not work.

This device has the following loop resistance thresholds selected.

Those. The loop resistance in the range of 540 ... 5900 Ohms is considered normal. Any resistance value outside this range will trigger an alarm.

Connection diagram of sensors (detectors) to the security loop.

Both normally closed (NC) and normally open (NO) security sensors can be connected to one loop. The main thing is that in good condition the circuit had a resistance of 2 kOhm, and when any sensor was triggered, it caused an open or short circuit.

To increase the noise immunity of the system, the device digitally filters loop signals.

In principle, everything should be clear. The following are connected to the PIC12F629 microcontroller:

• Two loops through RC chains R1-R6, C1, C2, providing
  • formation of loop power supply;
  • analog signal filtering;
  • coordination with the input levels of the PIC controller inputs.

To determine the resistance of the loops, a microcontroller comparator is used. An internal reference voltage source is connected to the second input of the comparator. The reference voltage source (VS) values ​​for comparison with the upper and lower resistance threshold values ​​are set by software.

• Through the RC chains R7-R10, C3, C4, two remote control buttons and an LED are connected through the current-limiting resistor R11. The device provides digital filtering of button signals to eliminate bounce and increase noise immunity.

It is worth explaining the purpose of resistor R17. The GP3 input of the microcontroller has an alternative function - 12 V power supply for programming the microcircuit. Therefore, it does not have a protective diode that limits the voltage at the level of the supply voltage. When the voltage is 12 V at this pin, the microcontroller goes into programming mode. Resistor R17 reduces the voltage at the GP3 input.

• Through two transistor switches VT1, VT2, the microcontroller controls the siren and external LED indication. Because these elements can be connected with a long cable, the transistors are protected from line surges by diodes VD4-VD7. Transistor switches allow switching currents of up to 2 A.
• The 5 V voltage for powering the PIC controller is produced by the D2 stabilizer. Don't ignore the VD8 LED. Its functions include not only indicating power, but also creating a minimum load for the microcontroller. If the PIC controller consumes a current of less than 2-3 mA (for example, in reset mode), then the 12 V voltage through resistors R8, R10 can raise the microcontroller supply voltage above the permissible level.
• The inputs for the 12 V power supply and the backup power supply are isolated by diodes VD2, VD3. A Schottky diode is used as a diode VD2 in order to provide priority to the power supply when the voltages are equal to the backup power source.

I assembled the device on a board measuring 54 x 45 mm.

Installed it in the case old alarm system. I only left the power supply.

The remote control performed in plastic case dimensions 65 x 40 mm.

Software.

Resident software is developed in assembly language. The program cyclically resets all variables and registers. The program cannot freeze.

You can download the firmware for PIC12F629 in HEX format.

Controlling the security alarm from the remote control.

The remote control is a small box with two buttons and an LED.

It is better to install it indoors near the front door. Using the remote control, the alarm is turned on and off, and the secret code is changed.

Modes and control.

When power is first applied, the device goes into ALARM DISABLED mode. The LED does not light up. The device remains in this mode during the working day.

To turn on the alarm (ARM mode), you must press two buttons at once. The LED will start flashing rapidly, and after 20 seconds the device will go into ARMED mode, i.e. will begin to monitor the status of the sensors. This is the time it takes to leave the room and close the front door.

If you press any button during this period of time (20 seconds), the device will cancel the security mode and return to the ALARM DISABLED mode. People often remember something just before leaving a building.

20 seconds after switching on, the device will go into ARMED mode. In this mode, the LEDs of the remote control and the external display unit blink approximately once every second. In ARMED mode, the state of the sensors is monitored.

When any security sensor is triggered, the LEDs begin to flash rapidly, and the alarm system counts down the time after which the siren will sound. This time (30 seconds) is necessary in order to have time to turn off the alarm by typing the secret code on the remote control buttons.

There are 2 buttons on the remote control. Therefore, the code looks like a number made up of digits 1 and 2. For example, code 121112 means that you need to press buttons 1, 2, 1 and 2 three times in sequence. The code can have from 1 to 8 digits.

If the code is entered incorrectly or incompletely, you can press two buttons at the same time and repeat the code.

When the code is entered correctly, the device goes into the ALARM DISABLED mode.

If the correct code has not been entered within 30 seconds after the sensor is triggered, the siren turns on. You can disable it by typing the correct code. Otherwise, the siren will sound for 33 seconds and then the device will turn off (enter ALARM DISABLED mode).

It remains to explain how to set the secret code. This can only be done from the ALARM DISABLED mode.

Both buttons must be pressed for 6 seconds. Release when the remote control LED lights up. This will mean that the device has entered the secret code setting mode.

Then wait until the LED goes out (5 seconds). The device will go into ALARM DISABLED mode, and the new code will be saved in the internal non-volatile memory of the microcontroller.

Because Since the microcontroller of the device is clocked from an internal low-precision oscillator, the indicated timing parameters may differ by ±10%.

Security alarm states.

In practice, working with an alarm system comes down to actions.

• Leaving the premises. Press two buttons at the same time and close the door within 20 seconds.
• Upon entering the room. Dial the secret code within 30 seconds.

Disadvantages, possible improvements.

The device can be easily modified for your own specific conditions. All improvements concern only the hardware. They do not affect software.

• It is advisable to install two sirens. One in the external indication and warning unit, the other in a hard-to-reach place. The current of the transistor switch (2 A) allows this to be done.
• It would be necessary to protect the siren wires from short circuits with a transistor current stabilizer. In the presented version of the circuit, an attacker can short-circuit the siren wires and when the alarm is triggered, short circuit power supply.
• If desired, you can connect powerful and high-voltage sources of light, sound, etc. through electromagnetic relays. Allowable current keys allow this, and the keys are protected against surges when switching the relay winding.
• You can use a battery as a backup power supply by adding a simple charging circuit to the circuit.

Appearance installed system alarms.

Currently, only the front door opening sensor is connected to the device. I plan, over time, to add security sensors. Two loops are enough to protect our two-story building.

By the way, if only one cable is used, then a 2 kOhm resistor must be connected to the second one.

There are other options on the site forum software devices. There you can discuss and ask questions about this project.

IN modern world It is almost impossible to do without security equipment - this is especially true for protecting your real estate from robbers who are constantly improving their methods of entering a house, apartment, cottage or garage. For such cases, electronic security systems in the form of alarms are effective. These security barriers minimize the likelihood of theft and allow the property owner to react in time to a dangerous situation. Today, many companies offer wide choose multifunctional alarms, as well as their installation and maintenance. Depending on the complexity of the security kit used, its cost will also depend, which can sometimes be quite large. If a home owner does not have the opportunity to purchase and install an expensive security kit, he thinks about how to make an alarm system with his own hands. It turns out that this is not so difficult process– it is important to have at least a little understanding of electronics and electrical installation work oh, and making an alarm won’t be too difficult.

Advantages of a homemade alarm

Despite the fact that a homemade alarm system is created at home, it has a number of advantages that allow it to compete with factory-made security systems.

Firstly, the simplest do-it-yourself home alarm system can be implemented even from improvised means that are available in household. Almost every home has an unused mobile phone, elements of actuators for various household equipment, etc. If something is missing, you can buy it for pennies at any radio market. The financial costs of a security system created at home are minimal.

Secondly, a homemade alarm can be easily changed in design at any time and modernized to suit changing operating conditions at the site. Not with every factory security system it will be possible to do this.

Flaws

No matter how good your security alarm project is, it is not without its drawbacks. The main ones include the following:

• lack of built-in protection systems against various devices that are used by attackers to disable alarms;
• the inability to connect such devices to security systems of security companies;
• It is difficult to independently implement complex security configurations that include a wide range of security and functional sensors and actuators;
• homemade simple alarm does not support the ability to conduct audio and video monitoring from a protected facility;
• without basic knowledge With electronics, you won’t be able to make your own security system.

What types of alarms can you make yourself?

At home, you can independently implement several options for security systems that will allow you to solve specific tasks for real estate protection.

• Motion sensor based alarm

A simple alarm for an apartment with your own hands can be created on the basis of a conventional motion sensor, which is equipped with lighting systems installed in entrances and on staircase landings. If you connect a siren to such a sensor instead of a lighting element, you will get a basic security system that sound signal will warn you that someone is in the protected area.

• Alarm systems based on ready-made kits

For those who don’t want to “rack their brains” on how to make a homemade alarm and what devices to use for this, you can use ready-made kits, which are sold on every radio market. You will only need to draw up a diagram of the protected areas and purchase the appropriate sensors and actuators for this. In the future, you will have to install the purchased elements and configure them to perform the appropriate security functions.

• Alarm based on magnetic contact sensors

For those who are thinking about how to make an alarm system at home that will respond to the opening of doors and windows, an option using magnetic contact sensors will be optimal solution. Distinctive feature Such sensors are that they include two elements - the sensor base itself and the magnet, which must be in direct contact. As soon as this contact is broken, the light and sound device connected to the sensor will be activated.

Using an old, unused cell phone, a highly effective homemade security alarm can be created using GSM communication capabilities. With the help of such a security system, it will be possible not only to activate the actuators connected to it, but also to notify the owner of the house about the danger through the channel mobile communications, sending to him mobile device SMS message or calling.

For those who do not know how to make an alarm with their own hands and temporarily cannot afford to purchase a ready-made one, they can install a simulator of the presence of a security system. To implement a basic signaling simulator circuit, you only need led indicator, two AA batteries, a current-limiting resistor and a housing for the location of the listed elements. The glow of the LED will indicate that the object is under guard - this should scare away thieves. But long time It’s not worth relying on security with the help of such a dummy - it’s better to figure out how to make an alarm yourself or buy it in a store.

Equipment for collecting alarms at home

A simple alarm system for a home can be built using the following set of devices:

• a set of sensors - for a simple security system, these can be motion control devices at the site, as well as opening sensors;
• siren and light-emitting devices - they will signal the activation of the security sensor;
• regular switch - used to turn off the alarm;
• autonomous power sources - these can be batteries or rechargeable batteries that will support the operation of the alarm system in the absence of power in the external network;
• mobile phone– needed in the case when a security alarm is created for a home with the function of notifying the owner on his mobile devices;
• a set of tools for installation work, conductors, mounting elements - with their help, the assembly and installation of an alarm system at home will be carried out.

Alarm creation process

The beginning of work on developing your own security system should begin with the creation of a project for the future alarm system. It will depend on him how to make a home alarm system so that it provides protection to all potentially dangerous areas. After compiling detailed plan You should make sure that you have the required devices and parts, some of them may be at home, and some will have to be purchased.

On initial stage the appropriate sensors are installed along the perimeter of the object, as planned in the project.

Note!

In order for the security alarm to perform its functions when they are triggered, actuators and mechanisms are connected to the sensors.

They can be connected through a specially prepared circuit, which includes an electronic turn-on delay timer and switching relays. In this case, the DIY security system will not work immediately, but after a set period of time, which is necessary so that the owner of the apartment can disarm it. For this procedure you need to install the usual push button switch, which must be located in a hidden place so that the thief cannot independently disable the security before the siren turns on.

One option for creating an alarm yourself:

If a do-it-yourself alarm is created for notification via a cellular network, then the sensors must be connected via a mobile phone, which, in parallel with the activation of the siren, will send an alarm signal to the owner.

Why is it beneficial to use a homemade alarm system?

By designing and creating an alarm system with your own hands, the user adapts it as much as possible to the specific operating conditions in his home, as well as to the tasks solved by the security system. Not every ready-made alarm from the kit can be optimally suited to specific conditions, and it is not always possible to upgrade it.

conclusions

The simplest DIY alarm system can be created in a fairly short time with minimal financial costs. But the protective effect it provides is quite high. This guarantees the owner the confidence that his property is not in danger.