DIY GSM module for car alarms. How to make a GSM alarm with your own hands

If you have an old mobile phone with buttons lying around at home, then do not rush to throw it away.
In this article I will describe how you can do it mobile alarm from an old push-button mobile phone.

Where to start making?

Alarm assembly instructions

• Glue the smallest part onto the button.
• We glue the largest part at the top of the phone above the screen, use a nail to guide both parts and glue them along the same axis.

Installation

No money for a professional alarm system for your apartment or car? No problem! You can always easily make an alarm from GSM phone with your own hands. The main thing is that your arms are straight. Moreover, this cunning electronic guard will call your phone itself, reporting the intrusion and raising the alarm. How to do this? Yes, very simple! You will need any simple mobile phone, the main thing is that it has a speed dial function. If you are making an alarm for a car, then you will also need a car charger. To quickly disable a homemade security system, we need a simple key switch.

Homemade car alarm from your phone

Preparing the device: We disassemble it, cut a hole on the keyboard above the button with the number “2”, using a soldering iron, carefully solder two wires to the contacts of this button. When the wires are shorted, a button press will be simulated. After that we collect the phone.

We buy a new SIM card and insert it into the device. We turn on the speed dial function and assign a number to the “2” key that the phone will call in case of intruders. To prevent burglars from immediately detecting your phone, turn off the backlight of the screen and keyboard, turn off the ringer and vibration.

We connect the charger to the phone, to which we need to supply power. Most best option— throw the wires directly from the battery.

All that remains is to connect the wires from the telephone button to the driver's door limit switch. We include a key switch in the circuit to be able to turn off the car alarm from a mobile phone when needed.

That's all - the security system is ready. As soon as someone opens the driver's door, you will receive a call on your phone. As a bonus, you can connect the search beacon function to your phone number and you can always find out the location of the car.

Mobile phone as an alarm system for a house or apartment

The solution presented above can be modified for use in a typical apartment. In this case, we need a door sensor - a reed switch. The alarm scheme from the phone looks like this:

We prepare the phone in the same way as in the case of a car alarm. On front door We attach a magnet and a reed switch to the jamb. We connect the reed switch contacts to the contacts from the button. Don’t forget to include a key switch in the circuit to quickly disable the security. With power, everything is simpler here - we connect the charger to the phone and plug it into a power outlet.
Well, that’s all - the simplest security system from a mobile phone is ready!

GSM alarm system - blocker

The proposed scheme for blocking a car engine using cell phone, is simple and does not require large expenditures.
To do this, you will need any cell phone with a new SIM card, a phone charger from the car’s on-board network, a small number of radio components for the switch unit and a button. All this can be purchased at any radio market.
The cell phone is put in /vibrator/ mode and leads are drawn from the vibrator to the outside, for which the phone must be disassembled, the vibrator itself removed, and the ends removed, determining the polarity (it is advisable to install a connector). To eliminate the function of turning off the vibrator when charging the phone, you need to charge the battery directly, for which a connection is made from the battery connection contacts or a shunt is installed.

A new SIM card must be installed in the phone to eliminate false positives, and only you should know the number via sms ” messages the circuit does not respond.
When you dial a phone number in the car, the standby mode will work and the indicator light will light up; after pressing the brake pedal, the engine will be locked. The unlock button is installed in a secret place of the car, out of sight; unlocking is carried out when the ignition is on by briefly pressing the button.
The lock indicator is displayed on the free peephole of the dashboard; if available or installed additionally, it is best to connect to the right turn indicator; with this connection, the car will immediately indicate a right turn after the lock is activated, and the turn indicator on the panel (in some cases with sound) will indicate the fact that the blocking was triggered is only natural for you.
The switch block is assembled according to the “block diagram”, temporary chain R 1, C 1 is selected so that K1 switches approximately on the 5th ring in the phone, keep in mind that if you redial quickly, the switch will occur earlier because The capacitor will not completely discharge.
The phone is installed in a secret but accessible place, because if the battery is disconnected, it will turn off after a few days, do not forget to turn it on. R 5 is selected in such a way that the phone battery does not heat up, about 30 Ohms.
The switch's power is connected to the ignition switch through a fuse or to a point that already has a low-current fuse. The blocking relay is installed separately and opens the ignition circuit or other devices responsible for engine operation; in operating condition, the relay is turned on.
For convenience, set the number in your phone to speed dial with one button, and also remember or write down the number in case it is not possible to call from your phone.
To enable the alert function, use the “alert scheme” scheme. Configure the phone in the car to call with one button, to your number, carefully solder the “call” pin to this button, and the “hang up” pin to the hang up button (identify and solder to the connector of the button matrix). Connect the relay to + siren. If the car does not have an alarm system, connect to the door limit switches, changing the polarity; in case of guarding a garage or apartment, also use a limit switch or reed switch. On your phone, enter this number as an “alarm” and set separate melody. If you answer an “alarm” call, you can listen to what is happening at the facility and take the necessary measures.
If you have one button to hang up and turn off the phone, connect only the call.
Once every 4 months, top up your balance a little so that your number is not blocked.
There is also the possibility of detecting the location of the vehicle because it will contain a cell phone.

GSM alarm system for garage

GSM alarm system for garage The easiest way to protect a garage and other objects is to use an old, unnecessary cell phone, of almost any model.
To do this, you need to set up your phone to dial your number with one button, for example “2”, and turn off the ringer and vibrator. Next, you need to carefully disassemble the phone and solder the wires parallel to the “2” button in a convenient place; it is best to solder them to the connector from the button matrix (determine with a tester). To charge the phone, use a standard charger for this phone, adding a diode and a resistor of about 30 ohms.
For a telephone with an end call and a power off on one button, use diagram 1 with a normally closed reed switch, this is important.
For a phone with separate end call and switch off, use scheme 2 and a reed switch with three contacts; in the phone, solder another wire to the end call button, one of the wires will be common.
Place your cell phone and charger in a hidden, safe place. Install a reed switch on the jamb and a magnet on the door or gate. Install the switch in a secret place or camouflage it as a light switch.
Limit switches can be used instead of reed switches, but they are not reliable in a wet environment.
Before leaving, turn on the alarm and close the door; if the alarm is assembled according to scheme 1, a call may come in, just answer it. After entering, turn off the alarm and also answer the call if it comes. This might be useful as a sanity check. If the alarm system is assembled according to scheme 2, calls do not have time to arrive.

The scheme has a significant drawback: if the gate is closed immediately after penetration, the alarm will not work. Therefore, use a simple device (see figure) on which the reed switch magnet is installed.

It works as follows: before leaving the garage, lift the bar with the magnet up and rest it on the flag; when you close the gate, the magnet will rest against the housing with the reed switch and move back, the flag will lower. If you open the gate, the magnet will also lower, respectively, if you now close the gate, the reed switch will not work. It is advisable to install axial springs on the axis of the bar and flag.
The advantage of this solution is that the alarm works during a power outage, which often happens in garages.
Don’t forget to check the alarm, lift the magnet before leaving, and top up your account a little every four months so that you don’t get disconnected.

Annunciator based on the old one cellular GSM phone (Kalmykov Boris)

The device was used on a car in conjunction with a volumetric security alarm sensor (not discussed here). The simplest option was created based on NOKIA phone 3310 (Figure 1), but any can be used, with a long-press speed dial feature on one button. Below we will discuss the use of other cell phones, with a different operating logic.

From the very beginning I will say that the cell phone requires modification: several wires (depending on the chosen circuit) are soldered to the keyboard. Be careful.

For NOKIA 3310, on any digit of the abbreviated dial, you “enter” the “owner” number (in the diagram there is a “Favorite button”), turn off the call beeper in the phone (for privacy) and solder the wires from the circuit (the vibrator must be turned off).

The alarm signal is released from the button that is triggered when the car interior door is opened (S1) or the “dry” contacts of the Volume Sensor (S2).

The circuit works in this way: when the doors are opened or a foreign object appears in the controlled area, the IC timer (NE555) generates a pulse of at least 1.5 seconds. The “Pressing” of the short dial button “favorite button” is simulated and the call to the “owner” cell phone is made. Based on the number displayed on the “owner’s” mobile screen, he decides whether or not to run to the car and with what “object”. You can “answer” a call and hear who or what is on the microphone at the far end. Since the circuit implements auto-pickup, if you wish, you can call the protected facility and listen to what is happening there.

Used element base does not contain

The logic of the work is as follows:

scarce components. The timers have a domestic analogue K1006VI1. For galvanic isolation of the created unit and the cell phone, any optocouplers can be used. When using only normally open sensor contacts, the elements: R1, VT1, S2 can be excluded.

It is possible, with further refinement of this circuit, to order the “object” to execute a command: detonate the squib, turn off the engine, etc. (I'll talk about this below).

For phones with speed dialing with 2 buttons, that is, we press the speed dial button and then the call button, the circuit solution shown in Figure 2 is suitable. It further shows a further improvement of the circuit by introducing a motor blocking unit. An approximate version of the resulting diagram looks like this:

The logic of the work is as follows:

When you call this mobile phone (in a car), the middle timer goes off, and then the bottom one. The output pulse is about 10-15 seconds. If, after the first dialing, you “fight back” and dial the same number again, then there is a simultaneous presence of output pulses on the middle and lower timers. This fact is recorded by the “wiring “AND”” circuit made on diodes in the base circuit of transistor VT2. As a result, the thyristor opens and holds “0” at output 9. Any blocking can be started from it (Relays, etc.). About “triggering” » blocking is indicated by LED1.

The lock is reset by briefly pressing button S2.

The devices were tested on cars owned by me and my friends, they were used in summer time when parking on the street, near the house. The unit was powered from an autonomous source - a small-sized battery of a computer backup power supply.

The appearance of the two resulting devices using Siemens C25 and C35 is presented in the photographs.

The good news is that the “unfashionable” mobile phone, which has been lying on the shelf for a long time, is again in service worthy of respect. Yes, the spirit of the radio amateur in us will not dry out!

Alarm based on a cheap cell phone (without microcontrollers and processors) (gsm-guard.net)

Operating principle of the alarm

After opening the contacts of the security sensor (limit switch or reed switch), the mobile phone cyclically dials the last number dialed on it by closing the contact pair of the “Call” button using an electronic relay.

The schematic diagram of the device is shown in Fig. 1. The device consists of three functionally complete units: voltage stabilizers with a charger (DA1, DA2, DA3, VT1, VT2), a logical control unit for closing the “Call” button (DD1, DD2, VT4) and an activation unit (DD3, DD4, VT5, VT6).

The charger made on the DA1 stabilizer provides charging of a sealed lead acid battery GB1 batteries with a voltage of 6 V and a capacity of 4 Ah (RB640E, RB640BS - made in China, widely available).

After supplying a supply voltage of 12 V (this supply voltage is selected to allow the device to be used in both stationary and automotive versions without recalculating the circuit elements, in the stationary version it is possible to power the device from a voltage source of 10...30 V with the appropriate selection of relay K1 and recalculation of resistors R1-R3), relay K1 is activated and, with its contacts K1.1, connects the battery to the charger. Charging current begins to flow through resistors R9 and R10. If it exceeds the value of 0.1 C (0.4 A for the specified battery), the voltage across resistor R8 will reach 0.6 V. The opened transistor VT2 shunts resistors R6 and R7, which leads to a decrease in the output voltage charger and limiting the charging current to the required level. At the same time, the voltage on resistors R9 and R10 opens transistor VT1, LED HL2 turns on, indicating that the battery is charging. As charging proceeds, the voltage on the battery increases and when the charging current decreases to less than 0.02 C (80 mA), the transistor VT1 closes and the LED goes out, which indicates the end of charging. In this state battery can be connected to the device indefinitely. The HL1 LED indicates that the device is connected to the network. Relay contacts K1.2 eliminate the influence of device elements on the battery charging mode, because The common wire of the device nodes, when powered from the network, is connected to the battery charging current limiting node (transistor VT2 and resistors R8-R12) and the device nodes are thus not in the battery charging circuit. The HL3 LED indicates the “Backup power supply” state. It turns on when the mains voltage is lost and a battery is connected to the device.

The DA2 stabilizer is necessary to bring the input voltage (12 V) to the battery voltage level (6 V) and provides power to the entire device. Stabilizer DA3 DA3 powers (3.6 V) mobile phone transmitter.

The logical control unit for closing the "Call" button of the telephone provides the necessary time delay when leaving the room, sequential double actuation of the electronic switch, leading to the closing of the "Call" button of the telephone (the first closing of the button calls up a number from the phone's memory, the second - calling it) and a cyclic algorithm call in case the phone receiving the call is busy.

The device is activated to open the contacts. As soon as the contacts SF1 (door sensor) open (this will happen when the door is opened), the device goes into alarm mode - it starts calling the previously entered number, repeating a series of calls with a period of approximately 1 minute. until the activation node is powered off. At the moment power is supplied to the control unit by closing the “Call” button of the telephone through the contacts of relay K3.1, charging of capacitor C6 begins through resistor R17. This charging takes approximately 20 seconds. During this time, the RS trigger on elements DD1.3, DD1.4 is forcibly held in the zero state (at the output of element DD1.3 low level) and does not respond to changes in the level at the lower input of element DD1.4, and therefore to the state of the door sensor SF1. During this time you must leave the premises. The output level of the trigger is inverted by transistor VT3 and is supplied to the lower input of the element DD1.1 and to the input R of the counter DD2 high level. As a result, counter DD2 is kept in the zero state, and the multivibrator on elements DD1.1 and DD1.2 is blocked and does not generate pulses. In this state, all outputs of counter DD2 will have a low level, transistor VT4 is closed, relay K2 is de-energized and its contacts are open. This state of the device corresponds to standby mode.

Let's assume that while the device is in standby mode, the door is opened. The contacts of the SF1 sensor opened and a high level entered through resistor R16 to the lower input of element DD1.4 in the circuit. Trigger DD1.3, DD1.4 switches to the single state, the voltage at the collector of transistor VT3 decreases to almost zero. In this case, the multivibrator is activated on elements DD1.1, DD1.2 and pulses are sent to the input C of counter DD2. The pulse repetition period is 7 s. At the end of 1 and 3 pulses of the multivibrator, a high level appears alternately at outputs 1 and 3 of the counter, respectively, which leads to the opening of transistor VT4 and the operation of relay K2, which with its contacts K2.1 twice, with an interval of 14 s. closes the contacts of the "Call" button of the mobile phone. At the end of the fourth pulse at input C of the counter, diodes VD4, VD5 close, which leads to the closing of transistor VT4. At the end of the eleventh and thirteenth pulses at input C of the meter, the contacts of the “Call” button of the telephone are closed twice again, etc., i.e. The button closes cyclically every 10 multivibrator pulses.

The HL4 LED indicates pressing the phone's "Call" button (in principle, it is necessary at the stage of setting up the device - it can be eliminated in the future).

The activation unit is designed to control relay K3 using the reed sensor SF2. The relay contacts close and open each time the sensor contacts are closed (each time the magnetic key fob is brought to the installation site of the SF2 reed switch). The node controls a logical node that closes the “Call” button of the telephone when entering and leaving the room, i.e. when arming and disarming. This ensures the supply or removal of supply voltage (6 V) to the logical control unit of the phone's "Call" button.

The activation unit consists of a single-vibrator on a DD3.1 trigger, a DD3.2 trigger, a VT5 transistor and a K3 relay. After power is supplied to the device, relay K3 is de-energized, contacts K3.1 are open. When the contacts of the reed switch SF2 are closed, the contact bounce pulse triggers the monovibrator and generates a positive pulse lasting about 0.5 s. At the same time, a high level appears at the output of trigger DD3.2, transistor VT5 opens, relay K3 is activated and its contacts K3.1 supplies power to the logical node. The next time the contacts of the reed switch SF2 are closed, the single-vibrator again produces a single pulse with a duration of about 0.5 s, which leads to the fact that the trigger DD3.2 changes its state - a low level appears at the output of the trigger, the transistor VT5 closes, the relay K3 is de-energized and the contacts K3. 1 break the power supply circuit to the logical node for controlling the “Call” button of the phone. Thus, each closure of the contacts of the reed switch SF2 changes the state of relay K3, the contacts of K3.1 of which, in turn, supply or turn off power to the logical node.

The intermittent signal generator on the DD4 chip is used for half-second audio notification of activation - deactivation modes, i.e. Every time you briefly bring the key fob to the installation site of the SF2 reed switch, an intermittent sound is heard beep. The generator consists of two interconnected multivibrators, one of which, based on elements DD4.3 and DD4.4, generates pulse trains with a repetition frequency of about 2 Hz at the output, and the second, based on elements DD4.1 and DD4.2, generates filling pulses with a frequency of about 1 kHz. The generator is started by applying a high-level control voltage to the lower input of element DD4.3 from the output of the monostable trigger DD3.1. The glow of the HL5 LED additionally signals activation.

The general operating algorithm of the system is as follows:

1. When leaving the room, briefly bring the magnetic key fob to the installation site of the SF2 reed switch. A half-second beep and the glow of the HL5 LED indicate that the system is armed;

2. You must leave the room within approximately 20 seconds, during this time the system will not respond to opening or closing the door;

3. If the door to the room is opened unauthorized, after about 25 s. (this time depends both on the frequency of multivibrator pulses on elements DD1.1 and DD1.2, and on the dialing speed determined by the GSM network) a call is made to the phone number last dialed on the mobile phone - transmitter;

4. Continuous dialing to the subscriber occurs for approximately 45...50 s., at this time the receiver phone rings, then after 50...60 s. After a pause, a repeated forty-five-second dialing occurs, etc. cyclically;

5. After receiving a notification about a break-in by the receiver phone, by pressing the “Call” button on it, it is possible to listen to the protected object within 45… 50 s.;

6. To unlock the system, after opening the door for about 20 seconds (this time depends on the frequency of the multivibrator pulses on elements DD1.1 and DD1.2), briefly bring the magnetic key fob to the reed switch SF2. At the same time, a short beep sounds and the HL5 LED goes out.

The device uses RES22 relays, RF passport 4.500.129 (K1); RES 49, passport RS 4.569.026 or RS 4.569.032 (K2, K3). You can use other relays with the corresponding number of contact groups. K1 - for response voltage 12 V; K2, K3 - for an operating voltage of 4...6 V. Diodes VD1, VD2 are replaceable with any that can withstand a current twice the charging current (400 mA).

The transistors indicated in the diagram can be replaced with any of the KT 315 (VT1, VT3, VT6), KT 3102 (VT2), KT 815 (VT4, VT5) series.

The BF1 telephone capsule is used from the same telephone used in the device. It must be carefully removed from the phone body. Stabilizers DA1, DA2, DA3 are placed on three needle-shaped heat sinks measuring 45 x 20 mm.

All parts, with the exception of the door sensor, reed switch of the activation unit, telephone capsule and LEDs, are mounted on a printed circuit board made of single-sided foil fiberglass 1.5 mm thick, dimensions 125 mm x 60 mm.

The phone is connected to printed circuit board two pairs of wires. One pair is soldered directly to the printed conductors going to the contacts of the "Call" button, the second - to the printed conductors of the phone's power supply. In addition, a microphone is carried outside of the phone by a shielded wire, which is used to listen to the room.

A properly assembled device requires minimal adjustment.

With the battery disconnected, power is supplied and, by selecting resistor R6, the voltage at the charger output is set to 6.75 V. Instead of the battery, a 10 Ohm resistor with a power of 2 W is briefly connected and the current flowing through it is measured. It should not exceed 0.4 ... 0.45 A. The voltage of 6 V and 3.6 V is measured at the output of stabilizers DA2 and DAZ, respectively; in extreme cases, resistors R15 and R26 are selected to adjust these values.

To check the functionality of the entire device, turn on the transmitter telephone and dial the telephone number to which you will need to call.

The security alarm board, telephone and battery are installed in a common durable plastic case. LEDs (5 pieces) are located on the front panel of the case (for secrecy, LEDs do not need to be installed). The SF2 reed switch can be located both inside the housing and outside in a hidden place. The SF1 sensor is placed on the door frame if the alarm is used indoors, or a standard door switch is used if it is a car. In the auto version, it is advisable to use an existing car security alarm in conjunction with the described alarm system, applying a high level when the existing alarm is triggered to the lower input of element DD1.4 of the logical unit for controlling the closure of the phone's "Call" button (in this case, the SF1 sensor and resistor R16 are turned off).

Also, a microphone and a telephone capsule, removed from the phone body, are fixed inside the case. Two small holes are drilled in the case and a microphone and telephone capsule are glued from the inside to these holes. 12 V power is supplied to the unit through a connector located on the side surface of the case. In the author's version, two nodes are added to the basic version of the security alarm (Fig. 1): a motion sensor (not shown in the diagram) and a speech module (Fig. 2).

The digital output of the motion sensor is connected to the lower input of the DD1.4 element (in this case, the SF1 sensor and resistor R16 are turned off). When movement occurs in the sensor's coverage area, a high level appears at the RS trigger input, which leads to the launch of the multivibrator and the logic node counter.

The speech module (Fig. 2) is designed to pronounce the phrase “The system is activated, please leave the room” when the system is activated (by bringing the key fob to the reed switch when leaving the room). However, you can record any other phrase for playback if you wish. The speech module consists of a speech recording and playback chip DD1 and a power amplifier DA1. The technique for recording speech into the ISD 1416P chip is presented in. When leaving the room, bringing the magnetic key fob to the reed switch SF2, a high level appears at pin 12 of the DD3 trigger. In this case, a low level appears at pin 24 DD1 of the speech module, which leads to the reproduction of the voice phrase previously recorded in the DD1 chip.

The motion sensor and speech module are also installed in the common body of the system.

View printed circuit board shown in Fig.3 and Fig.4.

Connection points are shown in Fig. 5.

Can a thing be considered secure if it does not have any security measures or if it has an ordinary lock? Of course not. The most popular protection is an alarm, but its cost is quite high, and it is not possible to install an audible alarm on every item.

We suggest watching a video recording that shows in detail how to make an alarm out of an ordinary old mobile phone that can be attached to any thing or device.

To make an alarm, we will need:
- old mobile phone;
- headset;
- Hens-fries;
- long wire;
- radio switch.

The essence of the device is that the phone will send a signal to another device. The call keys can be soldered anywhere.

We will use hen's fries. This will give us the opportunity to use phones that are not completely dead.
Take any headset from an old mobile phone and cut off the microphone from it.

Wrap the microphone with electrical tape and solder two wires to it. Soldering must be done in the place of the key that must be pressed when calling.

We take a regular radio switch, which can be bought at any stall for 10 rubles. You can attach this switch to a door or window frame. You can try attaching such an alarm to your car. At the top of the switch there is a kind of button that is pressed when the door is closed. If an intruder breaks into the apartment, then the button comes to starting position and a signal is sent to the work mobile phone to indicate that the door is open.

In the phone, you must enter a call on the last dial key and connect the hands-free wire to it, which will already be connected to the radio transmitter and a headset with a microphone.

The switch to which we will solder the wiring has three legs. The middle leg is for closing, and the two side legs are for soaking.

We must solder the wiring to the two outer legs. When the top lever button is pressed against the switch, the circuit opens and a cell phone call is sent. If the switch is a parrot, then we need to open the door 2 times.

You can also use a switching crank. You need to use a weight with three outputs. Girkom needs to buy the KEM3 brand, but it is not always highly effective. It requires precise setup.

It is important to use phones that can last up to one month in standby mode.

This type of system can be used as a bug. Using a hidden microphone, you can hear what is happening in our apartment. When the door opens and the radio switch is released, the handset will automatically be removed.

Installing an alarm in your garage is a very smart decision. At the same time, it is not necessary to buy something expensive and sophisticated. You can install the simplest GSM alarm system and with your own hands.

All you need for this, besides a soldering iron and basic knowledge of electronics, is:

• old unnecessary mobile phone (necessarily push-button);
• magnet;
• hermecon (sealed contact, regular or with three contacts, depending on which connection scheme you use);
• wires and a regular single-key switch.

Theoretically, limit switches can be used instead of hermecon, but in a humid environment they are not very reliable. Why make an alarm system that you can’t rely on?

The installation of the GSM alarm system itself takes place in several steps:

The principle of operation of such an alarm is very simple: when the gate opens, the reed switch closes the contacts and the phone rings your number.

In order to put the alarm in the “combat” position and, conversely, turn it off, an additional switch is provided in the circuit. Where exactly to place the telephone, switch and other structural elements depends on the structure of the garage. The main requirement is that these places be protected from moisture and prying eyes . Actually, the more inconspicuous the installed system, the better.

An undoubted advantage of such an alarm system is its independence from the electrical network. You just need to charge your mobile phone battery on time, using a standard adapter. If you have electricity in your garage, then it is advisable to install this adapter into the network, as shown in the diagrams above, so that the phone runs directly from the battery only during power outages.

Finally, we need to provide one more important nuance. This GSM alarm needs a certain time to trigger– a few seconds while a connection to your number is established. Therefore, if intruders quickly close the doors immediately after breaking in, the circuit will open again and the call will be reset.

Do you know how it is produced? This article will help you avoid major mistakes when installing an alarm system.

Video surveillance is also good for home protection. And video surveillance kits, which you can find out about at, will help you save time and money when purchasing equipment.

If you want to independently choose video surveillance equipment and install it, we recommend that you read the article located at

To prevent this from happening, you need to equip the magnet on the moving part of the gate with some kind of additional device, which will not allow him to open the circuit again. There are a lot of options here, it all depends on specific device gate and from your ingenuity.

The simplest option is to make the magnet move slightly from its place when the gate is opened. Then, if the gate is closed, the magnet will not come into contact with the reed switch and will not open the circuit. To bring the system into initial state, you will only need to move the magnet to its original place.