What kind of laser pointer can be used for signaling. Laser security alarm from a pointer. What is a perimeter security alarm?

Full functioning of the security system is ensured by devices that record changes in the external environment: physical deformation of material objects inside the protected area, unauthorized movement around the territory, etc. Perimeter security sensors are devices that detect changes that occur and transmit a signal to the control panel. Their main task is to register crossing the perimeter of the site so that security can promptly prevent illegal entry.

Basic requirements for security sensors

Wireless perimeter security sensors can be linear or volumetric (for example, radar). Linear sensors using a specific signal (for example, infrared radiation) create a certain boundary within the space, upon crossing which a signal is transmitted to the central control unit, notifying about the presence of movement. Volumetric security devices monitor changes in a certain area of ​​the territory, and not just its borders.

Criteria that determine the basic requirements for the perimeter security system of a country house or any other facility:

• the degree of effectiveness of early detection of violation of territory boundaries by any person or object;
• following the outlines of the perimeter as accurately as possible;
• eliminating the presence of “dead” zones in the protected area;
• installation should be least noticeable to an outside observer;
• level of influence weather conditions, atmospheric precipitation, seasons should be kept to a minimum;
• ignoring external factors not related to the area of ​​illegal invasion (noise, vibrations of passing vehicles, movement of animals, birds, presence of industrial elements);
• inertia in interaction with sources electromagnetic radiation, lightning strikes, etc.;
• the ability to calibrate settings that allow you not to react, for example, to the movements of animals, trees and bushes;
• low false positive rate.

Features of the perimeter system

Outdoor perimeter security devices differ from their counterparts:

• moisture-resistant housing that protects against precipitation;
• protection from intense sun rays;
• resistance to temperature changes, high and low temperature influences;
• equipped with a battery that lasts for several months;
• there is no need to install power lines;
• autonomous operation;
• correction of settings.

The quality of the security system depends on:

• professional skills of the organization that calculated, designed, and installed a security alarm. The system may consist of several types of motion detectors, the proper placement of which within the perimeter largely determines the effectiveness and speed of early detection of illegal entry;
• the state of the enclosing structures, where a security sensor is often installed. An unstable support can cause false alarms when exposed to wind, precipitation (for example, hail, heavy rain).

Factors determining the choice of designing a perimeter security scheme:

• location;
• relief of the adjacent territory;
• the possibility of creating a right-of-way in front of the protected perimeter;
• closest location of motorways, railways, airport and other transport facilities;
• the presence of vegetation near the borders of the territory, as well as in controlled areas;
• distance to the nearest power lines.

Application specifics

Perimeter security consists of distributed or discrete devices, equidistant from each other, sometimes forming a chain of several kilometers. In this case, the devices must be resistant to weather changes, clearly transmit the signal and its changes, easily undergo remote diagnostics, and are least susceptible to false alarms.

Instrument signals depend on:

• physical, mechanical characteristics of the fence, support, where they are quite strongly integrated (rigidity, height, quality of material, etc.);
• correct installation of individual elements and the entire system;
• a well-chosen range of devices for transmitting data about the perimeter and its territory.

The perimeter security system must be easily combined with other systems: fire safety, video surveillance, etc.

Operating principle

The way wireless devices operate is identical in design: the transmitting device sends a signal along a strictly defined path, and the receiver records this signal. Any changes in signal duration, frequency, phase, amplitude. are recorded as signs of illegal border crossing, the presence of a stranger on the territory.

Beam sensors for perimeter security are structurally divided into:

• two-block, where the receiver and signal emitter are located separately. those. make up two blocks. A certain distance is allowed between them where the emitted signal passes. Each device has a range limitation;
• mono-case devices, the transmitter and receiver are combined inside one housing. The receiver picks up the reflected signals sent by the transmitting device. Such devices are also limited in their coverage range of the controlled area.

Changing signal parameters, which indicate unauthorized intrusion into the protected area:

• interruption of the signal between the transmitting and receiving blocks of the device. This applies to laser and infrared devices;
• changing parameters, signal characteristics (radio wave devices);
• Availability physical changes fences, other structures where the device emitting a signal is fixed (strain gauge controllers that detect deforming effects from the outside).

In addition, the devices used can determine not only the physical crossing of borders, the presence of an outsider, but also the speed of movement, overall dimensions, and temperature.

Infrared

An infrared sensor is the most common device that uses infrared radiation, which is invisible to humans. In this case, the beam has all the other characteristics of the color spectrum. The receiver and emitter are simple in their structure, installation, and use. The sent beam is caught by the receiving unit, and the result is recorded by the control panel.

The IR sensor is also capable of detecting the temperature of an object. For perimeter installation, you should purchase devices that are protected from moisture, extraneous thermal radiation, and exposure to direct sunlight, which change the quality of the transmitted information.

Simple installation, cover a large space for control, it is possible to adjust the settings to eliminate false alarms due to animals and vegetation. At the same time, they are subject to the influence of precipitation and phenomena (fog, rain), which significantly deteriorate the quality of transmitted radiation. The range is limited by the properties of the infrared beam.

In addition, infrared barriers installed on the fence of the territory are used to protect the perimeter.

Ultrasonic

They are perimeter volumetric devices. The receiver picks up the reflected ultrasonic radiation of objects and objects located inside the controlled area, thus determining their characteristics, movements within the space or their absence.

Ultrasonic devices do not have a high degree of accuracy; they are most often used indoors limited spaces, volumes, for example, are installed to protect cars and small enclosed spaces.

Distinctive features that do not allow you to fully rely on these devices when protecting the territory:

• low sensitivity to environmental changes;
• exposure to temperature changes in the external environment;
• frequent false positives;
• influence strong wind, loud noises from external objects;
• influence of air humidity level.

It is possible to make a homemade laser device if certain starting materials are available.

Seismic

Seismic sensors operate on a different principle, when vibration is detected due to physical, mechanical impact from an external object. The data obtained helps determine that there is illegal entry of a person inside by overcoming the fence of the territory.

The degree of sensitivity to vibrations is regulated by the settings. It is important that the fence where the seismic sensors are mounted is stable, durable, and has a rigid material.

Laser

Laser motion sensors for perimeter security use the triangulation method of measuring the distance to an object, i.e. The laser beam, reflected by the object, necessarily returns to the receiver at a certain angle. The laser beam has high accuracy, the ability to detect the slightest irregularities of an object.

The exception is objects with a completely mirror surface, which reflect the beam to its exit point. In other cases, the reflected beam will fall inside the receiver of the device, regardless of the size and location of the object within space.

The angle of incidence of the beam changes with increasing distance to the test object, thus it is possible to determine its speed of movement, intensity, direction of movement, distance. The received data is read by a microcontroller built inside the device body. The microcontroller calculates the angle of light distribution across the photodiode receiver, and from this data determines the distance to the object.

Laser motion sensors for perimeter security are characterized by a high degree of measurement, linearity, and reliability. Capable of capturing different colors of the spectrum, also determined by the microcontroller.

Radio beam

Radio beam sensors consist of a receiver and transmitter spaced at a certain distance opposite each other. The peculiarity is that an elongated control and detection area, similar to an ellipsoid, is formed between them. The diameter can reach several meters. Short-wave radiation operates inside this zone, changing its parameters when a foreign object or object enters the controlled area.

They are usually installed along the perimeter of the territory. Weak spot of this system – availability dead zones with reduced sensitivity. Therefore, the installation occurs with cross placement of transmitters and emitters. Also, the distance above the ground of 30-40 cm is poorly recorded, which is another weak side radio beam security system.

The location of the system must be on a straight, even terrain; no vegetation or any objects are allowed to enter the zone. Designed to detect a person who crosses the border of the territory at full height.

Radio wave

Radio wave sensors have greater radiation focusing. For determining external changes Ultra high frequency waves are used. They are not susceptible to precipitation and weather conditions to the same extent as infrared ones. The controlled area of ​​the protected area is larger.

The advantage is the ability to monitor external changes in more detail, for example, the radiation phase shift, changed amplitude, and transmission frequency are analyzed.

They are also characterized by a low percentage of false positives, thanks to the ability to adjust the degree of sensitivity using settings. Structurally, they can look like decorative items for the site, which allows for hidden installation.

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The market for systems to protect objects from break-ins and unforeseen incidents is saturated with sensors that help establish comprehensive control over housing. However, not every device is capable of providing reliable security, and connecting low-quality, cheap equipment leads to unexpected problems. As an alternative to motion sensors, a simple and fail-safe laser alarm is used, which is triggered when an object enters the beam spectrum.

What is the operating principle of a laser beam alarm?

Alarms with a laser beam are usually purchased in a ready-made kit, but if desired, you can make them yourself without spending a lot of effort and money. The entire operating principle of a laser alarm is associated with a special infrared beam, which is directed at a certain angle to the opposite wall of the room where the photocell is mounted.

Any object falling within a given spectrum creates refraction that can send a signal to a special detector. After reporting a violation, the built-in speaker will notify residents or security of the intrusion.

The laser detector kit includes the following construction materials:

• Relay;
• The simplest microcircuit from a flashlight;
• Photocell;
• Power unit;
• Resistor;
• Detector;
• Generator.

Due to the fact that the laser light flux does not scatter and is constantly directed in one direction, using a reflector system you can create a varied pattern that cannot be avoided. Small pieces of mirrors located at a certain angle at different ends of the room are used as reflectors.

The process of assembling laser elements and parts

The assembly principle consists of sequential soldering individual elements alarms to the board. First of all, you need to decide on the place where the laser alarm and photocell will be installed. Most often, such mechanisms are mounted in the lower part of the room at a level of 30 cm from the floor, which allows you to hide the device from prying eyes.

The video shows an experiment with laser signaling:

The installed laser on one side of the wall is connected to a relay and power supply, and in the opposite place, at a distance of no more than 10 m, a photocell is attached with the expectation that the beam will fall vertically onto the lens. When an object enters the spectrum of the beam, the photocell begins to heat up, the relay transmits a signal to the resistor, and the latter to the detector.

The siren acts as a repeller, emitting a signal with a power of up to 100 dB, which can be heard at a distance of about 100 m.

A conventional lithium battery should be used as a power supply, since it will consume a minimum amount of energy and is practically necessary to issue an alarm signal.

Modern radio amateurs propose to integrate a communication module for the functionality of the system, which will make it possible to send an SMS or voice message to a specific number, which will not only scare away the robber, but also try to detain him.

In this article we will tell you how to make a laser alarm. The idea is to make such an alarm as shown in movies about superheroes.

This laser alarm simulates a stretch when a thin wire is stretched 20 centimeters above the ground (floor). When an intruder enters the protected area and pulls a tripwire, an alarm is activated. What if you do a laser alarm and a tripwire at once? That's right, this will turn out to be quite interesting.

The alarm system discussed in the article is primarily intended for use in airsoft, but it can also be used to protect residential premises, garages, etc.

The principle of operation of a laser pointer alarm is quite simple.

The PIC16F688 microcontroller controls the laser module that sends the beam, which must be returned through the mirror. The reflected beam is received by a photoresistor. The PIC16F688 microcontroller checks the state of the photoresistor and if the laser beam is blocked, it activates a sound signal.

The laser signaling circuit is quite simple and is shown in the following figure:

To change operating modes, use switch S3 - select the operating mode: laser and / or stretching:

1. Laser + stretching.
2. Stretching.

The photoresistor must be placed inside the tube to prevent contact with sunlight or other light sources. To eliminate the possibility of accidental activation of the laser alarm.

And the laser pointer needs to be modified by soldering the wires to the place where the batteries are installed.

The following figure shows the laser module and photoresistor tube.

To combine both elements, they must be aligned and glued together, for example, by cold welding or plastic. Thus, they are assembled parallel to each other.

For the stretch version, a microswitch is used, located in the upper part of the laser alarm housing. The mikrik lever protrudes above the body, through the window, so that fishing line, thread or thin wire can be hooked onto it.

Now you can finally finish the case by making holes for the LEDs, power button, mode switches and siren.

When installing the emitter with the receiver, please note that it must be possible to adjust this part of the laser alarm.

The alarm uses a modified portable PC beeper because it is quite small and very loud. But him electronic circuit must be modified so that it can be connected to the PIC16F688 microcontroller.

Upon completion of assembly, it is necessary to check the functionality of the alarm from the laser pointer.

The scheme works as follows. When the power is turned on, the device enters setup mode, checks the laser and lets us know if the reflected beam has returned correctly to the receiver. At this point you need to adjust the mirrors. If the reflected beam is adjusted correctly, the red LED lights up.

After adjusting the beam, you need to press the button 1 time to exit the setup mode and enter the operating state.

If the laser beam is blocked, the PIC16F688 microcontroller will turn off the laser and activate the siren.
The siren will work until you press the button. Voices)

The proposed design may be useful for protecting non-permanent openings - windows, passage doors - or installed along the perimeter of an open object. The operating principle is triggered when the laser beam is interrupted by an intruder. Despite its simplicity, the system turned out to be quite reliable and economical, and the red laser operating in short pulse mode is practically invisible to the intruder.

Figure 1. Laser security system transmitter diagram

The transmitter, the diagram of which is shown above, consists of a short pulse generator and a current amplifier loaded onto a laser pointer, which is easy to find in almost any stall. The generator is assembled using elements DD1.1, DD1.2 and, with the ratings of the frequency-setting circuit indicated in the diagram, operates at a frequency of about 5 Hz. Next, the signal goes to the differentiating circuit C2R3, which forms short pulses lasting about 10 μs. This not only makes the device economical (one six-volt battery type 476 is enough for more than a year of continuous operation of the transmitter), but also invisible to the intruder.

Next, the pulses are equalized in shape and amplitude by elements DD1.3, DD1.4 and are sent to an amplifier assembled on transistor VT1. The amplifier is loaded onto a laser pointer, which is modified - the batteries are removed and the cone-shaped tip is removed. Resistor R7, connected in series with a resistor “imprinted” into the laser flashlight board itself (its nominal value is about 50 Ohms), is current-limiting for the laser LED, toggle switch SA1 turns on the continuous operating mode of the emitter, necessary for adjusting the transmitter-receiver system.

For greater economy and frequency stability, the DD1 microcircuit is powered by a voltage reduced to 3-4 V, the excess is suppressed by resistor R6. The average current consumption by the transmitter does not exceed 10 μA; the LED consumes about 20 mA per pulse, so there is no power switch. The transmitter remains operational (of course, with a decrease in range) when the supply voltage is reduced to 4.5 V.

The receiver, the circuit of which is shown in Figure 2, is assembled on an integrated circuit DA1, the sensitive element is a photodiode FD263-01. When replacing it, you need to take into account the length of the illumination pulses - the response time of the LED to illumination should be 5-10 times lower than the laser pulse duration.

In its place, for example, FD320, FD-11K, FD-K-142, KOF122 (A, B) and many others will be able to work. In response to each flash of the transmitter, the receiver generates a pulse at the output high level CMOS amplitude. It can be used for further processing. To exclude external illumination, the photodiode must be installed in an opaque tube that acts as a hood.

Setting up the system comes down to its alignment. This is done visually, aiming the laser beam at the photodetector as accurately as possible. To do this, switch SA1 to switch the transmitter to continuous radiation. After completing the adjustment, both the receiver and the transmitter must be firmly secured. In principle, such a system does not require “micron” adjustment. During the experiments, it worked reliably when the photodetector, spaced 50 m from the transmitter, was located in a circle of radiation scatter with a diameter of 30 cm.

Based on materials from “Radio” No. 7, 2002.

Fireworks to everyone! If there have been robberies in your area more than once or there is such a danger, and you want to sleep peacefully at night, then you have probably thought about the question: should I install an alarm?
But complex systems security is not always affordable, and you have to spend more and more on installation and maintenance. True, there are also cheap alarms, but attackers have long learned to turn them off, so today I will show you how to make a simple and inexpensive laser security alarm yourself.

Laser signaling circuit

Since there are many circuits today, I showed you what I think is the most current one, using the very popular NE555 IC.

For assembly we will need the following components: piezo buzzer(which will emit a signal), two resistors(750 Ohm, 130 kOhm), microswitch, photoresistor and an integrated timer chip NE555.

A little about the NE555 timer

It was developed in 1972 by Signetics. It has a wide range of supply voltages: from 4.5 to 18 V, the output current reaches 200 mA, and the microcircuit itself does not consume much. The accuracy of the microcircuit does not depend on the supply voltage. There are a lot of elements inside the timer: about 20 transistors and many other parts.

The chip has eight legs:

1. Earth
2. Launch
3. Exit
4. Reset
5. Control
6. Discharge
7. Nutrition

It is important to remember that no more than 1/3 of the supply voltage should be supplied to the second leg (start), and 2/3 of the supply voltage to the sixth leg (stop)!

Let's return to our laser. The laser beam is directed at the photoresistor. When it is not irradiated, this leads to an increase in voltage on the sixth leg of the microcircuit, as a result of which the buzzer turns on. You can turn off the speaker by pressing the microswitch. Let's watch a short video:

The choice of resistor R1 and R2 depends on the supply voltage. For example, my supply voltage is 4.5 V, so I chose resistors R1 - 130 kOhm, R2 - 750 Ohm. Since laser batteries run out quickly, the laser can be connected to a more powerful power supply, usually 4.5 V.

With the help of several mirrors you can cover the entire room with rays, the main thing is that the last mirror directs beam directly into the center of the resistor.

The laser alarm will always warn you when you are nearby, but you can also connect a more serious scheme: for example, with SMS notification. If interested, let me know. That's all, sleep well, have good dreams!

Best regards, Edgar.