DIY security alarm. DIY car alarm with immobilizer - auto electrician Schemes of homemade security alarms on microcircuits

Schematic diagram of a homemade security alarm on a microcontroller:

The starting element is the LX19B (or LX19C) motion sensor. These are freely sold in electrical goods stores and are not expensive. The security alarm sensor requires a small modification: on its board it is necessary to cut the tracks of the relay contacts that close and remove two wires from them (according to the “start” signal diagram). When a person appears in the sensor's action space, the diagram closes to common wire“Start” contact and the time countdown begins from 9 to 0 seconds. This time is displayed on a seven-segment indicator. During this time, use the buttons to enter the correct code. Only then will the alarm turn off for 30 seconds. This time is enough to enter the room and turn off the alarm from the inside.

To dial the code, 4 buttons are used: Key1, Key2, Key3 and Key4 All. They are pressed in the following order: 1-2-3-1-2-1. These buttons can be located anywhere on the keyboard, but they must be pressed exactly in correct sequence. All other buttons (Key4 All) are connected in parallel. When you press any of them, the code set is reset and you have to start all over again. When the time counter displays “0,” dialing the code is prohibited. You need to move away from the door or stand still until the sensor resets the time to “nine”, and then dial the code again. The more buttons on the keyboard, the less likely it is to guess the code.

Any car howler is used as an alarm sound emitter. Original scheme The secret police was assembled on an indicator with a common cathode, taken from some Chinese device. Even the smartest DataSheet doesn’t know its name. Therefore, for convenient repetition, I redrawn the circuit, board and firmware for the more well-known (but not the brightest) ALS324A indicator, also with a common cathode. The board option can be used, for example, as in the archive, and if desired, the button board can be changed.

If someone likes the circuit, but some other indicator is at hand, for example with a common cathode or a common anode, I will change the signet, circuit and firmware according to your wishes and capabilities. Archive with files and microcontroller firmware on the forum. If you have any questions, I will be happy to answer them there. Good luck! Samopalkin

Discuss the article SECURITY ALARM DIAGRAM

Car security is a pressing and sometimes expensive issue. But if you have an inexpensive car, you can do simple car alarm with your own hands. To do this, you need minimal knowledge of physics, a simple microcircuit and the necessary radio components. They can be easily removed from old equipment.

To create an alarm, SC1006 series microcircuits are suitable, which are designed for alarms with increased level nutrition. And I also want to immediately note one point, if you have a truck like a forklift, then I want to tell you an excellent resource where you can select and buy spare parts, come in and choose.

Microcircuits can operate over a wide range of supply voltages. But it is best to power the microcircuits with a voltage of 5 volts.

They have a built-in zener diode, which allows them to be powered from a battery. The SC1006 microcircuit is one of these. Looking at the diagram, you can understand that Rated voltage makes it possible to use it for alarms. Based on these microcircuits, many alarms and signaling devices in the car have been developed.

The pulses emitted by the microcircuit, the frequency of which is constantly changing, create the howl of a siren. With every second it increases and is fed to the head. It is connected to two transistors, the second of which is a power amplifier. Instead of two conventional transistors, you can install one - KT829. It's much more powerful.

A piezo emitter is suitable as a sound head. It can be replaced with any high frequency dynamic head with a power of more than 10 watts. In order for the head to enhance the alarm effect, it must be installed in the acoustics.

A one-amp semiconductor diode is installed at the power input. It is necessary to prevent power overload.

The system uses a 30 kOhm resistor. The sound of the alarm depends on it. If you are not satisfied, you can install a variable resistor on which you can adjust the duration of the pulses and configure the desired sound.

If you attach a vibration or presence sensor to the alarm system, your car will be under reliable protection.
All the best….

The alarm system is designed to protect various objects of apartments, offices, cottages, cars and bicycles. And also to warn and inform people in case of emergencies

Happy opening summer season the issue related to the protection of country property brought for the season. The most popular among gardeners are homemade and purchased burglary detection and warning systems based on wireless sensors and gsm modules to signal an alarm or trigger. Many of the alarms and designs discussed are perfect for repeating with your own hands. In addition to standard security sensors these systems can use other optional equipment, such as smoke, flood and concentration sensors carbon monoxide, gsm sockets, etc. In this article, we will consider a security alarm for a dacha and a private home, which you can assemble with your own hands.

The principle of operation of laser signaling is as follows: when an object enters the area of effect of the beam, the laser stops illuminating the photodetector. The resistance of the latter increases sharply and the relay turns off. The relay contacts also turn off the laser. This is a variant of the simplest scheme.

When laser ray acts on a photoresistor, its resistance tends to zero, and when the laser is turned off, its resistance increases sharply and significantly. The photoresistor must be placed in a closed housing.

This alarm uses a ready-made module with a red emitter from a cheap Chinese pointer as a laser, which can be easily removed from the housing with your own hands

Selection simple circuits do-it-yourself alarms, mainly for indoors. Using a reed switch or microswitch with normally closed contacts as a sensor, the circuit also has a delay in turning on the alarm when leaving the controlled room, and a slight delay in triggering the alarm when entering.

A selection of simple sensor alarm schemes for protecting various objects, recommended for self-assembly with your own hands. The principle of its operation is based on direct touch contact and the triggering of one or another type of alarm indicator

Ready-made types of car alarms are given, as well as methods for their installation, modification and modernization. In addition, a selection of various homemade options alarms for making with your own hands.

In the first alarm scheme, a simple car guard is considered, which successfully worked on a VAZ car; in the second part, a similar design is considered, but with minimum set radio components

As observations of the operational reports of the Ministry of Internal Affairs show, greatest number thefts from closed premises carried out by opening the door. Even having a safe door with English locks will not give full protection. Therefore, to reduce the risk of theft, I recommend installing homemade alarm system on the door, which will play the role of active protection. And experienced thieves, seeing a homemade product, cannot know what it is capable of and will choose another object to attack.

The principle of operation of the first two circuits assembled with your own hands is very simple, you just need to monitor the integrity thin wire, secretly stretched across the territory of a protected facility or in it. The attacker does not notice and tears it, thereby causing an alarm signal that is transmitted by the call mobile phone at a pre-assigned number. The article discusses two options devices - simple on electromagnetic relays and more complex ones on transistors and microcircuits of the K561 series

A bicycle alarm for your iron horse will work if you apply some kind of vibration to it, that is, just lightly touch the bicycle and the alarm will go off. Anxious sound signal The alarm lasts 30 seconds, and after a few seconds it repeats, and so on until the bike alarm is turned off.

When leaving your home for a long time, you need protection from thieves - an alarm with a motion sensor is great option. The sensor can be installed on the wall next to or above the door, on the ceiling, or anywhere else. The principle of operation of the device is as follows: when motion is detected at a certain distance, an audible alarm is triggered.

This security alarm is a simplified version of the military analogue, which is used when it is necessary to provide security for a camp or any other facility in field conditions. The disadvantage of this design is one false alarm, which can be due to a fallen branch, a forest animal, or a similar break in the motion sensor, which is thin copper wire

The sensor reacts to an increase in air temperature to a certain value and to a certain level of smoke. The level of smoke is determined by the darkening of the gap between the infrared light and photodiodes. The temperature is controlled by a thermistor, the sensor is triggered at 45 °C, but this temperature can be easily changed within +20 °C. The homemade radio is powered by the main 9 V alarm unit and consumes a current of 10-11 mA.

Homemade alarm system based on the AVR microcontroller ATtiny2313 and a mobile phone.

The alarm system is designed to protect premises. And although there are already quite a few similar devices on the Internet, I decided to create my own, which I need for work. The operating principle is classic: a reed switch and a magnet are attached to the door. The door opened - the reed switch opened - a signal was received on the microcontroller (zero changed to one) - after a time delay, the relay activated, which with its contacts closed the shortcut button on the phone for a short time. The shortcut button is configured in advance to the desired number. You can use any push-button telephone with a quick call function. When writing the program, the task was to make a delay at exit and entry, and also after the alarm was triggered, transfer the circuit to passive mode, so that in the event of a long time open door the phone did not make constant calls and did not get on my nerves. Schematic diagram I tried to make it as simple as possible.

For the microcontroller I used a socket so that, if necessary, the microcontroller could be easily changed (for example, to change time intervals). For the relay, I also used prefabricated sockets, under which I placed diodes (diodes protect the transistors from breakdown by self-induction of the relay). Relay 1 - miniature type “TIANBO TR5V L-S-Z 05VDC”. If necessary, the relay can be easily removed from the socket and replaced with another one.

The installation was carried out on a breadboard, all parts are output, resistors are 0.25 W. I used the legs of the parts for connections; I also placed the parts (resistors and diode) under the microcircuit socket. The result is a compact board 40 by 40 mm. For clarity, wiring diagram I marked the sockets in red, the points where the legs of the parts are inserted in blue, the parts themselves in green, the microcircuit body, capacitors and relays in yellow. Relay 2 for the siren, made on a separate board. To charge the phone I used the standard Charger, which I connected to the timer. The timer turns on once a week for two hours.

Algorithm of device operation.

When power is applied:

Turning on the control LED HL2 to “OUTPUT”.
Checking the cable for rupture. If, after turning on the circuit, the loop is broken or the reed switch is open, the LEDs begin to blink at intervals of 1 second.
Exit delay - 1 minute
Transition to the “SECURITY” mode “SENSOR CONTROL” (Reed switch).
The control LED turns off and the circuit goes into security mode.
After the sensor is triggered, the delay to “ENTRY” is 25 seconds.
Turning on “Relay 1” (twice - 1 sec. and 4 sec.) - the phone button closes twice.
Delay 30 sec.
Turning on “Relay 2” - Turns on the SIREN for 2 minutes.
Turning on the control LED HL1, an indicator of security activation (you can not use it to increase secrecy).
The circuit transitions to passive mode - the circuit does not respond to the reed switch until the next power switch.

The security is turned off by turning off the 5V power supply. (the switch is located in a hidden place).

Intervals may vary by 5 seconds. depending on the specific microcontroller because I did not use quartz to simplify the circuit.

The device has been tested and shown to be reliable in operation (the length of the cable to the reed switch during testing was 14 meters). Anti-interference protection is provided both at the hardware and software levels. The program was written by me in Assembly language in the AVR Studio software environment.

Of course, you can purchase a security unit in a store. There are various devices on the market. But what if you don’t want to overpay for different options. Besides, your hands grow where they need to. No problem!

You can assemble a completely acceptable option yourself. This car alarm has nothing superfluous: central locking control, radio key fob. But the homemade product will protect your car from penetration using door and trunk limit switches. And also, using a shock-vibration sensor, it will warn the owner if, for example, wheels are unscrewed. By the way, did you know that it is much more difficult for an attacker to disable this kind of alarm. He doesn’t know what you could have introduced there. In addition, in the absence of a key fob, the degree of protection increases many times, since car crooks will not be able to read the code (after all, it is known that most hacks occur using this method).

Device diagram

Principle of operation is as follows. The signal from A1 vibration sensor goes to the amplifier, which is made on VT1, VT2 and controls the thyristor VS1. The base of transistor VT2 also receives a signal from the limit switches of the doors, hood, and trunk. A timer is assembled on transistors VT3, VT4, which controls the anode of the thyristor VS1. The VT3 base circuit uses a high-capacity capacitor C3. Due to this, when arming the securely hidden toggle switch, C3 begins to charge through the car siren and a circuit of resistors R6, R7. During the charging of the capacitor, VT3, VT4 will be closed, therefore, thyristor VS1 is locked. Due to this, the circuit is armed with some delay, giving the driver time to leave the car and close the door.

After 20 seconds, capacitor C3 gains capacity, VT3 opens and turns on the security system. Suppose there was an impact on the car or a door was opened. Thyristor VS1 is unlocked, C4 begins to charge through VS1, VT4, R10. The thyristor is designed in such a way that it remains open when passing direct current. When the door closes (the signals stop), the alarm siren will notify the owner of the intrusion. If the sensors were triggered when the owner appeared, then during the C4 charge (20 seconds) he will turn off the disguised toggle switch. If this is not done, then VT5, VT6 will open, relay KV1 will turn on, which in turn will connect the siren. In order not to disturb the neighbors and not to run to the car during false positives, such as a truck passing by, this car alarm has an alarm time limit function. It works as follows. When the contacts of KV1 are closed and current flows through R6, R7, capacitor C3 is charged. After a short time, VT2, VT3, VS1, VT5, VT6 will close and relay KV1 will turn off and arm again.

What details can be used to implement the circuit. The requirements for them are not critical. Capacitors and resistors of any type, preferably small ones. Relay KV1 with an operating voltage of 12 volts and a coil current within 100 mA. The power contacts of the relay must withstand a current of 5 A. But it can be reduced to 0.5 A if an intermediate relay is used.

The A1 vibration sensor is not difficult to make yourself. It is made in the form of a coil with a steel core, from which it is attached at a short distance permanent magnet on a flat spring. At the slightest impact on the car body, vibrations through the spring will be transmitted to the magnet. This, in turn, will create an alternating magnetic field, which will induce an EMF in the coil. The latter, Ø10×15 mm in size, is wound on a Ø3 mm steel core. For the winding, copper wire 0.06...0.07 mm is used. A magnet with dimensions of 25Χ10Χ5 mm must be secured to a spring using glue and thread. As which you can use a spring from an alarm clock. The length of the latter is selected within the range of 60 - 80 mm. When assembling the shock sensor, care should be taken to ensure that the magnet can be positioned as close as possible to the side of the coil. The finished vibration sensor should be placed in space so that the magnet is able to oscillate perpendicular to the surface of the earth.

Homemade vibration sensor

Now the most important thing remains - to hide the toggle switch through which power is supplied to the circuit. This issue should be approached with no less responsibility. Since you will have to use it constantly, but the attacker should not detect it.