The simplest alarm from a syringe. Homemade alarm for cars The simplest do-it-yourself alarm

Currently, you can find a huge amount of information on the Internet about alarm systems with notification over GSM networks, but is GSM dialing always necessary? Sometimes a simple, local siren system is enough to scare off a thief. After all, it is well known that when a siren sounds, a criminal abandons his evil intentions.
The most expensive part of the alarm system is the central unit. This is what I would like to do myself. Of course, there are quite simple circuits on transistors and logical elements, but they have low functionality and significant limitations in operation. A good alarm should at least have the following capabilities:

1 Adjustable alarm delay time so that the owner can safely disarm the system.

2 Adjustable siren time.

3 Sound indication. Countdown of the time for which it is necessary to leave the premises or disarm the system.

4 Light, external indication of the operating mode. Whether the system is armed or not.

5 Re-arming. After the siren stops working, the system should return to operating mode.

6 Limiting the number of triggers. Protection against a faulty sensor, so that the siren does not whistle for days until you disarm or the neighbors break it.

7 Power failure status memory. The power-on alarm shall continue to operate as it was before power-off.

8 The civilized way of arming is a code keypad or an i-Button key fob, not a secret toggle switch.

Probably, all this can be organized on logical elements, but just imagine how complex this circuit will be. There is only one conclusion - to use a PIC controller. I know that after this phrase, half of them lose interest in what is happening, but there is no way without it. And it's not so difficult, there are many detailed articles about the simplest programmers and programming.
Taking into account all of the above, we got such a scheme, well, and the firmware.

The total cost of all parts is $ 5-6. You cannot name a complex scheme. It does not need tuning, the main thing is to solder correctly. You can assemble it on the "mounting" or etch the board, if you need more than one copy. And using SMD elements, at least partially, in the end it can turn out like this:

The reader, quite decent looking, can also be made from improvised means.

Firmware, detailed instructions for setting up the device can be downloaded
Questions about the firmware, printed circuit board, manufacturing of the reader, as well as advice and recommendations, send to the author's E-mail

Everyone wants to live as comfortably and safely as possible. The desire to protect your home as much as possible from someone else's penetration is natural and reasonable. Therefore, technical ways to prevent cases of theft of property through the use of security alarm systems are popular.

The development of microprocessor technologies, controls, video surveillance and communications make them increasingly available for security for household purposes. However, attackers are also studying them, looking for effective ways to block or control. Our tips will help the home craftsman to reliably and covertly install a DIY security alarm system for a house or apartment, disguising them from the view of a potential thief.

The principles of creating a security alarm

A few decades ago, the burglar alarm system operated by means of limit switches connected by wires to a power source and light or sound displays, but now it is a complex of various technical systems that function autonomously and automatically. Security is created to notify the owner of the property about unauthorized entry into his zone in order to take effective measures to suppress the crime.

For this purpose, approaches to protected property are divided into the following lines:

1. access route control zone;
2. fence, structural elements of the building: basement, walls, roof, windows, doors;
3. interior rooms of rooms.

For their implementation, a security alarm system is created, consisting of:

• object control schemes;
• a logic block that processes information coming to it;
• sirens sensors;

Each of these components, working autonomously, provides its own specific tasks of protection and control.

Methods for monitoring the security zone

Detection sensors react to the intrusion of unauthorized persons in various ways:

• video surveillance;
• control of acoustic signals;
• breaking or changing the state of the circuit of the electrical circuit;
• mechanical stress and in other ways.

Detectors can be triggered by:

• electrical contact;
• changes in the magnetic field;
• shock mechanical impact;
• piezoelectric effect;
• capacitive current;
• optical-electrical conversion;
• sound or ultrasonic control;
• combinations of several signals and other methods.

Surveillance sensors monitor the object:

• a certain amount of space;
• parts of the surface;
• section of the access line;
• pointwise.

Reed switches - magnetic contact security sensors

The so-called magnetic locks can often be found in shop windows and on the front doors of premises. They allow the sensor with contacts and wires to be fixed to permanently installed elements, and the adjoining magnet to them on the opening doors.

Burglar alarm sensors of this type have become outdated for a long time: they are mounted in a conspicuous place, and it is not difficult for intruders to use an additional magnet, which by its field will block the operation of the detector.

Glass break sensors

Showcases and large glass windows attract intruders because they can be broken relatively easily and entered through the opening into the security zone.

To signal such actions, detectors are created that respond to:

• mechanical shock;
• extrusion with jacks;
• heating of glasses with blowtorches.

The installation of the sensor, as seen in the figure above, is carried out directly on the tested surface, which transmits mechanical or sound waves. They are picked up by electric shock-contact and piezoelectric detectors.

Passive sound sensors distinguish between two control modes:

1. low frequency caused by the impact of a hard object;
2. high frequency from flying debris.

Infrared sensors

Two principles are used to work:

1. passive temperature control of the security zone;
2. active tracking of the state of a free segment in space.

Passive detectors

It works by constantly comparing the temperature gradient in the directional zone. The appearance of a person or pets in it is quite enough to send a signal.

Attackers, knowing the zone or place of installation of passive infrared sensors, manage to bypass them, putting on protective suits that block the thermal radiation of the body. The firefighter's outfit is quite suitable for these purposes.

Active detectors

The receiver with the transmitter of infrared signals in the security zone works in a complex manner, constantly monitoring the passage of the control beam.

Since it is indistinguishable to the human eye, it can only be bypassed by knowing the exact location or using special optical technology.

Radio wave detectors

The principle of operation of such a security zone is based on the emission of electromagnetic waves into the room and the simultaneous reception of signals reflected from the inside of it. At the same time, they are constantly being compared.

When movement is detected in the controlled space, the balance between the added signals is disturbed and a command is issued to trigger the sensor.

However, the disadvantage of this control method is that attackers, knowing about the presence of a radio wave detector, can simply move slowly in its zone.

Capacitive sensors

The detector is tuned to the capacitive charge of the surrounding area and balanced with the electromagnetic fields around it. When the human body is in the zone of its influence, it destroys the created balance with its capacity. The sensor senses this moment and is triggered.

An attacker, when he knows about the principle of operation and the location of the capacitive sensor in the guard, blocks its action by using electrical protective equipment of electrical personnel. A hard hat, rubber gloves, an electrician's suit, and specialized shoes will prevent activation.

Combined sensors

The use of several methods of detecting intrusion into a protected object significantly complicates the actions of criminals. For example, the combination of a radio wave and a passive ultrasonic detector is still considered quite difficult to break. Such a security zone is very difficult to overcome.

However, attackers are constantly studying all the technical details of the newly introduced security systems, carefully developing measures to bypass and control them. This fact must be taken into account in your practice.

When using any burglar alarm, the main attention is focused on their hidden installation, closed installation, maximum restriction of persons who know about its work. After all, even close people, family members can accidentally let slip and provide useful information to potential criminals.

Methods of operation of sirens of unauthorized access

These devices can be assigned the function:

1. scare off an intruder approaching the protected object by giving a light signal or a siren roar;
2. promptly notify the owner and the security service about the penetration of strangers into the restricted area in order to take emergency measures of detention by the police brigade;
3. or to comprehensively solve several other tasks of control or protection.

Wired and wireless home communications, including Internet technologies, allow information to be instantly transmitted to the building owner.

Logic block operation

It is created taking into account the effective use of the functions of the selected detector and siren for the contour tasks of protecting a private house or apartment.

If earlier such systems were made by a home craftsman with his own hands from improvised means according to electronic circuits published in textbooks, now such designs are on sale with a fairly wide range of possibilities.

They are easy to customize to the individual requirements of local security using the available programming tools. The algorithm of work includes all the processes of receiving, processing, transmitting and accounting for tracked information.

Types of communication channels

Depending on the conditions of use, wired channels or wireless technologies based on the transmission and reception of radio waves are used.

It should be borne in mind that the reliability of their operation depends on the quality of the power supply, its reliability and If the attacker turns off the power at home, the burglar alarm will be taken out of operation.

To prevent this from happening, use either autonomous power supply from batteries or accumulators.

However, rechargeable batteries require constant monitoring of the technical condition and. Otherwise, they can also fail by playing along with the attacker.

Security alarm from China

Well-known online stores in China provide a wide range of electronic products for security. Their kit includes:

• control block;
• various detector designs;
• additional accessories.

This composition should be studied, carefully analyzed before purchasing.

Control module

Its appearance and composition of functions is repeated and at the same time differs in different models.

On the frontal surface are usually located:

• information display display;
• push-button switches for entering commands;
• built-in speaker and microphone jacks.

Under the cover at the back are:

• terminal blocks and connectors for connecting wires and cables of detectors and sirens;
• microswitches of module modes;
• SIM card for.

Equipment manufacturers make control modules in a beautiful case, which can be simply hung on a screwed-in screw or secured with adhesive tape to the wall near the front door. This convenience can end badly.

The attacker, having entered the apartment, will first of all look for a place where the burglar alarm is installed. He will try to quickly disable it: rip it off the mount, throw it into the water, for example. Keep your secrets a secret!

Detector

Structurally, the principle of operation of sensors of the main types is described above, and their appearance is shown in the picture.

A battery and electronic boards with mode switches are located inside the case with a convenient shape.

In addition to the security function, other detectors can work in the alarm set, for example, or even In this matter, each apartment owner or home master himself determines the list of necessary functions for his own needs.

Optional accessories

The equipment may include as separate accessories:

• various sirens;
• remotes key chains.

Sirens and spotlights

Due to their small dimensions, sounders can be hidden in the interior of rooms or in niches of stairwells, where they will fulfill their purpose - to scare off intruders, to prevent cases of theft.

Small-sized floodlights have sufficient lighting power for a private house.

Keychain for protection

Small size mobile remote controls can be easily stored in a pocket or bag.

They allow you to control the operating modes of equipment from different places, for example, to turn off the motion sensor when your people are in the room, and leave the window and door sensors in operation.

How to set up a burglar alarm

The factory instruction defines the sequence of actions for commissioning each set

Antenna installation

If an external rather than a built-in antenna is used in a logic block module, then a special socket is mounted for it.

The connection is made to this connector.

How to insert a SIM card

Installing a SIM card is fully consistent with the actions that we perform in a smartphone or mobile phone.

Putting into operation

When power is supplied from the 220 network, it is necessary to connect the adapter, and then turn the toggle switch to the ON position.

Communication settings

You will need to "bind" the individual SIM card number to the control unit. To do this, use the factory password, for example, 8888 and the SMS sending mode.

Then they connect an external siren and check the passage of signals between the blocks, starting from each detector, and receive SMS to the mobile phone.

Once again, we draw attention to the fact that all actions with the burglar alarm must be kept secret and not disclosed to unauthorized persons. We have specifically shown that for any technical novelty, attackers quickly find hacking tools.

This article provides diagrams of the simplest electronic alarms that can be made by anyone who is at least minimally familiar with electronics or just knows how to hold a soldering iron in his hand. Such alarms will come in handy in many cases. They can be placed on the windows if there is a small child in the house who can open them. There is a guarded parking lot on the doors of an apartment or garage. And when triggered, the watchman will call the police. You can put such an alarm in the apartment if you are friends with your neighbors. Even if you go on a hike, it is not a sin to spread a security loop around the camp at night in case of wild animals or strangers.

First scheme electronic alarm is simple to the extreme, it couldn't be easier. This is just one transistor, resistor and an executive relay. If an audible alarm is supposed, then instead of a relay, an audible siren or a howler is turned on.

Principle of operation: The security loop is a thin wire, or closed contact. When the wire is intact (or the contact is closed), the base of the transistor is grounded and the transistor is closed. No current flows between collector and emitter.

If you break the guard wire, or open the contact, the base will be connected to the power source through the resistor R1, the transistor will open and the relay (or siren) will work. It can be turned off only by turning off the power supply or by restoring the security loop.
Such an alarm can be used to guard your belongings, for example. A reed switch is used as a security contact, the alarm is hidden in the side pocket of a bag or backpack, and a magnet is placed nearby. If the magnet is removed from the alarm itself (move the thing), the siren will squeal in all voices.

Second circuit with more advanced custom functions

As in the first case, a security loop, a normally closed (in armed mode) contact or a reed switch closed by a magnetic field serves as a sensor. If the loop is violated, the alarm is triggered and its operation continues until the power is turned off. Loop recovery does not turn off the alarm, it will still continue to work for some time. The alarm has a temporary blocking button, which is necessary for the owner to leave the protected area. The alarm also has a response delay, which is necessary for the owner to turn it off when he enters the protected area.

Let's analyze how the circuit works. Before arming the alarm, you must turn off (open) the S1 switch. It must be installed in a secret place near the entrance. You can use, for example, a hidden reed switch, which closes - opens by rearranging an object with a built-in magnet, etc. This switch blocks the operation of the system and it stops responding to a loop break. When leaving, the switch S1 opens and the capacitor C2 begins to charge through the resistor R2. Until the capacitor is charged to a certain value, the system is "blind". And you have time to leave the facility by restoring the security loop or by closing the contacts. Choosing the values \u200b\u200bof the resistor R2 and capacitor C2, achieve an acceptable exit delay for yourself.

If the security loop is violated, then capacitor C1 will start charging through the resistor R1. This pair creates a slight delay in the alarm, and the owner has time to neutralize it by turning on the S1 switch. It is necessary to select the resistor and capacitor values \u200b\u200bfor a comfortable response delay time.
If the loop is violated by an intruder who does not know how to turn off the alarm, then some time after the loop is broken, the alarm will be triggered (both inputs of the D1.1 element will be logic "1", respectively, at the output "0". Having passed through the inverter D1 .2 it will again become "1" and open the transistor VT1 The transistor will discharge the capacitor C3 and through the inverter will open the transistor VT2, which will make the executive relay work or turn on the siren.

Even if the attacker quickly restores the loop, the siren will continue to work, since the capacitor C3 will be charged for a sufficient time through the resistor R3. It is the denominations of this pair that determine the alarm operation time after the loop is restored. If the loop is not restored, the alarm will work continuously.
Microcircuit - K561LA7, transistors - any n-p-n (KT315, KT815, etc.) Power supply - any with a voltage of +5 - +15 Volts. The executive relay or siren can be connected to a more powerful power source than the circuit itself. In standby mode, the circuit consumes practically no current (at the level of self-discharge of the batteries).

If you are the owner of an expensive car, then most of all this article is not for you. And if you have a rather modest car and you want to protect your car with minimal costs (which is not at all proportional to the quality), then this description is for you.
The fact is that car alarm should not cost more than 5% of its market value, which for a used car is an amount for which you cannot buy a ready-made, more or less reliable alarm. The danger for a car without an alarm is not only in its theft, but also in the very penetration into the salon, theft of property, documents, etc., which is very common in current conditions.
The damage may be small, or even more than the cost of the vehicle itself. In the traffic police, such cases are often not considered at all, since there is little evidence for them and they do not initiate a case at all, stating that you yourself have forgotten a purse or documents somewhere, and you did not have any money at all. My friends had several similar cases, although the cars were equipped with purchased alarms.
And the fact is that not expensive (although this is for someone else), and quite monetary standard alarms, scammers and thieves have long learned to bypass. And it became much easier to open (steal or rob) a car equipped with such a standard purchased alarm system. Now there are many different scanners with which an attacker reads the code of your alarm when you arm the car by sending a radio command from the remote control.

Everything, the "bad person" already has your code and he can easily open the car or close it, without attracting attention at all. Further, I think, everything is clear to everyone. Therefore, having such an alarm system, you significantly increase the potential theft or theft from the car, even in comparison if you simply locked it with a key, without the possibility of remote opening of the doors. And if we also take into account the human factor - the master who installs the alarm for you can naturally know how to turn it off, make a duplicate, etc.
Of course, most masters are decent people, but the facts show that if there is an opportunity, someone will always use it. The data can be transmitted to interested parties and "shoot" in a year or two after the installation of the alarm. It will be almost impossible to tie this together, and even more so to prove it.
There are still many reasons not in favor of standard low- and middle-class purchased car alarms, not to mention the expensive part.

Consider the functions that a simple, inexpensive do-it-yourself car alarm should perform:

• The alarm should respond to penetration into the car, for example, using an IR motion sensor, or from standard light buttons that are triggered when the door or trunk is opened (the cheapest option, easy to implement, but nevertheless quite functional).
• An intrusion car alarm should notify with a sound, a standard signal or an additional siren. This notification should last for a certain time, for example, two to five minutes, and then automatically turn off.
• After the alarm is triggered, the system must go into the unauthorized entry mode - it must be repeatedly triggered, block the engine start, etc.
• - The car alarm must consume a low current, excluding the discharge of the battery (standard or additional) during long-term parking of the car on guard.
• The mechanism of inclusion, transfer to the security mode and disable the alarm. In a simple case, a short delay (5-10s), after turning on the secret toggle switch, while leaving the car and closing the door.
• Easy to manufacture and connect with low financial costs with maximum efficiency.

Such an alarm will reliably protect even such a product as the Six-wheeled "Zaporozhets-Hammer"

Below is one of the most simple car alarm circuits that you can make yourself.

The car alarm combines an acoustic signaling, triggered by the closure of sensors (buttons for turning on the light of the doors and trunk) and when the ignition is turned on, and blocks the start of the engine.
This scheme is suitable for installation on domestic cars equipped with a classic contact ignition system (VAZ, Moskvich, Volga, etc.) and any foreign cars with a similar contact ignition system. (Previously, all cars had a contact ignition system - turned the key - contacts closed). Installation in many new cars is possible.

Homemade car alarm scheme quite simple and understandable to any novice radio amateur. All details are publicly available and cost a penny. The connection to the car's electrical circuit is also shown in the diagram. The bold line marks the alarm unit itself, which is assembled in a small plastic case, selected from available ones or can be purchased on the radio market - according to your taste.

Everything outside the bold rectangle is the elements of your car's electrical equipment, as well as other additional elements that are introduced into the car's circuit (K2 and short circuit sensors, two relays P1 and P2, toggle switch 51).

Two types of contact sensors are used - standard switches for interior lighting located in the doors of the car (they are connected in parallel, therefore one sensor K1 and one lamp of illumination H1 are indicated on the diagram), and specially installed sensors (such as door ones) under the hood and trunk lid, if the trunk not equipped with a standard switch, similar to a door switch - so that in the closed state their buttons are pressed and the contacts are open. When opened, the contacts must close.

The standard signal of your favorite car or an installed purchased siren can be used as a source of a sound signal of the car alarm system. The signal is switched on using an additional electromagnetic relay of sufficient power (since the current passes through the signal coil is decent), which must be installed in the engine compartment of the car - P1. The same P2 relay is used to block the ignition system. In principle, this relay can be placed in the alarm box itself. Its winding is connected parallel to the winding P1 and when the alarm is triggered, the relay P2 shunts the capacitor C of the ignition system with its contacts, which makes it impossible for sparking and starting the engine.

The car alarm is turned on by means of a micro toggle switch 51, which must be installed in a "secret place" inside the car (usually somewhere under the panel), known only to you and your trusted persons. After turning on the power, the device will not respond to the status of all sensors for 15-20 seconds. This time is spent on getting out of the car and closing the doors. After this time has elapsed, the car alarm goes into security mode.

To increase reliability, you can use an independent additional small battery, this is at will, desire and financial capabilities.

Even without an independent power source, such an alarm in modern conditions will be more reliable than a simple purchased one with a remote control. The cost is clear and so.

The system is economical. In standby mode it consumes less than 0.7 mA, trigger mode - 1.1 mA, and signal or siren current - 0.2-0.5 A

Additionally, you can add an infrared motion sensor - purchased or if one is lying around on the farm.

If the 220V sensor needs to be converted to 12V (8-20 Volts). A standard household motion sensor must be opened. The spherical part is removed by bending one support. The halves are fastened with latches.
You take out the board. The sensor is a passive IR receiver that responds to changes in IR radiation that hits it. Typically, the angle of view of the motion sensor is 180 degrees.

Another simple car alarm circuit without ICs

The circuit works on a similar principle, using the same sensors as in the previous case.

Short description:

SA2-SAn - intrusion sensors (door buttons, etc.). The VD5-VDn diodes are used to isolate the sensors, if they are used for other purposes. If the sensors are for signaling only, the diodes can be omitted.

The supply voltage supplied from any closed sensor through R1 C1 goes to VD1. The R1 C1 circuit generates a short current pulse even if the sensor remains closed. Capacitor C2 does not trigger the alarm when the SA1 toggle switch is turned off.

The output switch and multivibrator are assembled on elements C4, R4, R5, VT2, K1. The duration of K1 in the on position is determined by the selection of the resistor R5 (you can install a variable resistor), and in the off position - R4. The overall pulse frequency is set by C4. This part of the circuit requires more careful tuning. About 2 Hz.

On elements C3, VD3, VD4, a node is assembled, which forms an alarm delay when the intrusion sensor is closed. This is necessary to delay the siren sounding when the owner opens the car for 4-8 seconds to turn off the device (so as not to frighten others :-)). The delay time is set by capacitor C3. The discharge of the capacitor when the power is turned off is provided by resistor R3.

In this scheme, there is no node that would turn off the alarm after a while, this is the simplest option. If desired, such a unit can be modified by slightly complicating the design, or an autonomous time relay with periodic reset can be used.

VD1 - any low-power thyristor, for example KU101. You just need to select C1 (increase if the alarm does not work when the sensor is closed), R2 (decrease if it does not work) and C2 (increase if it works immediately when the circuit is powered on). Diodes - any low-power. Relay K1 - RES55A, or similar (selected according to the power of the switched current of the siren-signal). If you use a more powerful relay (more than 1A), then you will need to significantly increase the capacitance of capacitors C3 and C4 (this will lead to an increase in the size of the device). Therefore, if you have a rather powerful load, it is better to connect a powerful relay to the RES55A output. Transistors are also any, with an appropriate transition structure, and VT2 must withstand the relay turn-on current. SA1 - any small-sized switch (toggle switch).

To turn on the car alarm for protection:
1. Turn on the SA1 toggle switch with a closed sensor (with an open door). In this position, the circuit will not turn on and may remain for an unlimited time.
2. Close the door - the circuit enters the armed mode.

To turn off the car alarm:
1. Open the door (this will close the intrusion sensor).
2. Fast, within 8-10 sec. disarm - turn off the SA1 toggle switch.

Are thieves in the habit of climbing? Or the neighboring guys are trying to rob your apple trees or trample the beds, and there is no way to get a dog, then you just need an alarm. It is very expensive to buy a new one in retail outlets, but making a primitive but effective one yourself is quite simple, from scrap materials.

How to make an alarm from an ordinary one with your own hands, look at the video

To create an alarm, we need:
- wooden clothespin;
- battery;
- the wire;
- nylon threads
- button;
- soldering iron;
- electronic match;
- awl.

The wooden clothespin must be disassembled into two parts.

To the half that remained with the spring, we attach the finger battery to the flat side. You need to attach it so that the plus of the batteries is on the nose of the piece of wood.

You can fasten it with a nylon thread, making several turns in two places of the halves of the clothespin.

We take the tip of one wire and wind it on a pushpin needle. After that we hammer it into a piece of wood until it stops in the direction where the battery has a "+".

And immediately we solder the wire from this button to the plus of the battery.

We solder the second wire with one end to the minus of the battery.

After that, we take an electronic match or any other electronic device that will respond to changes in battery voltage (speaker, flashlight, etc.).

We wind one end of the wire onto the tip of a pushpin and hammer it into the other half of the clothespin.

We collect our clothespin.

We also need one more half of the clothespin without a spring. We make a small hole in her tail with an awl and thread a nylon thread.

Stretch alarm ready.

Principle of operation.

First of all, the created structure is installed with a nail, which is driven into the surface through a clothespin spring. Insert the free piece of the clothespin between the ends of the assembled clothespin and clamp it. We tie the free end of the thread to a fixed support (door or tree).

After that we connect the free ends of the wires together.

If you pull on the thread, the piece of wood will fly out of the clothespin, the contacts will close and a short circuit will occur. And you can immediately see that someone has entered your protected area.