The engine blocking relay is a car theft deterrent that allows you to remotely block the engine and perform control. Its use along with a car alarm turns an “alarm” into a whole anti-theft complex.

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Functions and operating principle

Depending on the manufacturer, the manufacturing technology and operation of the security system may vary. The principle of operation is to break the electrical circuit of the starter device when an unauthorized attempt is made to start movement.

The transmission of encrypted impulses from the blocker or the processor module of the anti-theft complex can be performed in several ways. This is done through standard electrical circuits, via a separate radio channel or via radio transmission.

Digital devices use a standard electrical circuit to transmit packet data. The wire has a special analog channel that allows for increased speed of information transfer. Packet data is collected virtually around the perimeter of the vehicle. Before sending information to the consumer’s remote control, the anti-theft complex diagnoses the code to determine its legitimacy. The data can be transferred to the consumer’s communicator or mobile gadget, depending on the capabilities of the “signaling”.

The essence of the blocker lies in the physical break of one of the power lines, and the control button is installed at the break point. This key is pressed at the beginning of the movement, which ensures the start of the power unit. If the button is released when trying to start the engine, it will not be possible. Using the key on the alarm relay, a signal is sent to open or close the contacts.

Andrey Kondrashov spoke about the principle of operation of internal combustion engine blocking relays.

If automatic mode is preferable, then the consumer can independently set the power unit blocking time using a timer. This option can be configured based on the temperature inside the car, a specified time interval, or the temperature of the internal combustion engine.

Design

The radio relay is made in a small block; the device body is usually made of plastic. Structurally, the block itself includes an electronic circuit, as well as a relay chip. These components are used to monitor specific controllers installed in the machine.

The automatic blocking module itself includes a set of electrical circuits. They are used to connect via the CAN bus or to the standard wiring of the machine. If the car is equipped with an alarm system with auto start, then a relay must also be connected to this system. The small dimensions of the case allow the installation of the power unit blocker anywhere in the vehicle interior. When choosing a location for installing the relay, you need to take into account the location of the points through which it will be connected to the standard electrical wiring of the car.

Blocking relay design

Kinds

You can find several types of engine blockers on sale. Let's look at the features of each of them in more detail.

Regular

Conventional analog devices can be made in several variations. The first option is considered the simplest to implement; it is installed in a microprocessor car alarm module. The broken electrical circuit is connected to the control module. The main advantage of such blockers is ease of installation and high fault tolerance. But these devices cannot be classified as anti-theft devices. If the criminal gets to the microprocessor unit, he can quickly restore the broken circuit.

There are more advanced analog relays. Such blockers are removed from the microprocessor “signaling” module and installed in the engine compartment. The control procedure is carried out via an electrical line that connects the relay to the anti-theft complex through a normal voltage supply. If voltage is supplied to the blocker, the circuit is closed; when there is no voltage, the contacts of the element are open.

The advantages of such devices include fault tolerance. Compared to the first option, the theft resistance of remote locks is higher, but it also cannot be classified as a full-fledged anti-theft means. If a criminal gains access to a microprocessor device, he can quickly apply voltage to the control power line. This will allow you to restore the broken chain and start the engine.

Analog engine blocking relays are not recommended for use, since they cannot provide effective protection against theft.

The Nördlich Bär channel showed the operating principle of a simple power unit lock.

Digital

Digital devices are divided into several types:

1. A simple digital blocker. A more advanced version of the above-described option visually looks similar, only for unlocking a digital pulse is transmitted through the control power line. In essence, it is a password; simple voltage cannot be used to unlock it. Such blockers are not susceptible to quick hacking, which makes them more reliable and fault-tolerant. The disadvantages include the presence of a wire from the microprocessor module going to the blocking relay, this will allow an attacker to determine the location of the relay installation. To prevent theft, the electrical circuit itself must be properly hidden.
2. Blocker without direct connection with the microprocessor module. The transmission of control pulses is carried out through the standard electrical circuits of the machine, the signal is made in the form of digital packet data. The advantages include the difficulty of detecting a device through electrical circuits; in practice, such blockers cannot be easily hacked. But a criminal can use special devices to interfere with standard electrical circuits, which will result in the signal not being sent to the relay and the blocking will not be carried out. Installation of such blockers is advisable if there is resistance to alarm noise; installation will require the help of a qualified specialist.
3. The next type of device is digital with transmission of control pulses via radio channels. It is impossible to identify such a blocker in a car using power lines; these devices are less susceptible to hacking. But a professional criminal will be able to use the same “noisemaker,” which contributes to the formation of interference and the impossibility of transmitting control impulses. In areas where strong radio noise predominates, operational difficulties may arise, this is especially true in large cities. During installation, the car owner must take into account all these points. It is important to ensure that the criminal cannot bypass the device using a noisemaker.

According to technical parameters, digital devices are divided among themselves:

1. By size. The device can be an imitation relay, made in a miniature case for hidden installation. On sale you can find sealed blockers designed for installation outside the car.
2. According to the value of switched current. Depending on the device, the blocker can be designed for 5-40 amperes.
3. By type of transmission and reception of signals. Digital devices can operate via electrical circuits, from an on-board network signal, or via a special radio channel from the main module. More advanced devices can work with transponder keys.
4. According to the length of the transmitted signal and the type of transmission. Packet data using a constant code is transmitted over 4-8 bit channels. When using dynamic locking, the code length will be from 16 to 100 bits. The length of the dialog code can be any; this option is considered the most reliable and safe.
5. If possible, protection from detection by dialing.

Digital device with direct connection to the unit Blocker without direct connection with the processor unit Digital device with a radio channel for data transmission

Wireless

Such blockers cannot be forced to open or close contacts by applying voltage. An electronic board is installed in the device body, which is controlled by an electromechanical component. The transmission of commands is carried out in encrypted form, so it is almost impossible to detect the signal and intercept it.

The main advantage of wireless blockers is that a consumer can simultaneously install several dozen such devices on a car engine, it all depends on financial capabilities.

Single wire

Single-wire devices are not susceptible to interference. To connect such blockers, not a standard electrical circuit is used, but a separate single-wire line, through which packet data is transmitted. This type of connection allows you to provide reliable protection from interference, increased loads, and also increase the power of the transmitted pulse. The wiring does not transmit code signals, so if a criminal wants to use a bug for hacking, he will have to find the appropriate cable.

The disadvantages of the devices include the complexity of installation compared to wireless blockers. To prevent intruders from turning off the relay, it can be moved to the engine compartment and an additional lock can be installed on the hood. Single-wire relays are not so in demand among consumers. The fact is that it is almost impossible to implement an invisibility lock with a wire.

The channel “WUST-TV - All about GPS monitoring” talked about installing a GPS tracker, as well as a blocking relay using the example of a tractor.

How to connect and configure?

You can install and connect the blocking device yourself.

Auto-latching relay

Let's look at an example of connecting a signal blocker Starline B62 Dialogue. On the main board of the microprocessor unit there is a blocking device with a group of switching contact elements. On Starline B62 this output is marked as X1. The maximum current generated is 15 amperes.

The connection procedure is performed as follows:

1. Before installation, the specific operating mode of the relay is programmed. Depending on the model of the alarm, the setup process may differ. In the case of the B62 Dialog system, programmable option 10 is used for configuration. Initially, the device is configured for a normally closed interlock.
2. Decide on the installation location. The installation must be performed in one of the standard electrical blocking circuits of the power unit. For example, you can install the device in the gap of the fuel pump or injectors.
3. Two of the three contact elements of the built-in blocker are connected to the created gap. Blue and white-blue wires are used for connection. These electrical circuits are included in the “signaling” package.
4. If the connection is made into a power line break with an inductive load, the magnitude of the current must be taken into account. The maximum switching parameter may be greater than the maximum current with which the blocker operates. This may cause it to break.

Remote latching relay

We will look at an example of a safe connection of a digital relay using the Starline P2 model as an example. A detailed device connection diagram is presented in the technical manual.

Before installing and connecting the blocking relay, you need to understand one of the operating modes of the device. It is determined by the consumer based on the state of the electrical circuit loop that comes out of the blocker board. If the loop is intact, then the closed mode is activated, if the loop is open, the normally open mode is activated.

Connection and installation:

1. The installation procedure is similar. The device crashes into one of the electrical circuits of the car - the fuel pump, injectors or starter device.
2. To connect, you need to go to the settings menu for the main “signaling” options. Select the blocker operation mode - 3 or 4 options 10, detailed information about the functions can be found in the service manual. Once selected, disable the option settings menu.
3. Connect the black cable marked MAC to the car body.
4. Turn off the ignition and click on the Valet service key seven times.
5. Turn the key in the lock to turn on the ignition. The siren will sound seven sound signals, this indicates entering the blocker configuration mode.
6. Within five seconds, connect the black cable marked ZAZH to the electrical line of the ignition system. If the device is paired, the siren speaker will play one long beep.
7. To leave the binding mode, turn off the ignition system or wait five seconds and the “signal” will automatically leave the menu. If you plan to use several relays, then install and connect the second device in the same way. When the second relay is successfully linked, the siren will emit two extended beeps.

If, in the event of an attempt to bind a blocker, the siren plays three extended signals, this indicates that the device has already been entered into the memory of the microprocessor unit.

A blocker that has been stored in memory cannot be linked to another communicator; to do this, you will have to reset all settings.

Andrey Kondrashov spoke about the independent implementation of car engine blocking.

How to choose a relay?

When purchasing a device, you need to take into account the main selection criteria and manufacturers.

Criterias of choice

Nuances to consider when purchasing:

1. The type of device that will be used. The type of blocker is determined in accordance with the needs of the car owner.
2. Overall dimensions of the device. To make the installation secret and the relay difficult to detect, give preference to blockers made in a small housing.
3. Decide on the installation location. If the installation is carried out in a salon, then any type of device will do. If you plan to install the relay in the engine compartment or under the bottom of the car, then buy blockers made in a sealed housing. They will prevent negative impact external factors for the operation of the device.
4. Manufacturer. The more famous the manufacturer, the more likely it is that their product will last a long time.
5. Technical parameters of the car. Blockers can operate with currents of different magnitudes. This nuance must be taken into account before purchasing in order to prevent the relay from failure under increased load.
6. Type of control signal used. Conversational encoding is considered the most effective.
7. Additional features. If a manufacturer claims that its product is protected from interference and scanners, we recommend that you read consumer reviews on the Internet about this model.

An overview of the selection parameters, as well as the Starline P2 relay, is given in the AutoAudioTsentr video.

Manufacturers and models

The most popular blocker models:

1. Pandora VM-105. A wireless device designed for installation in cars with a 12-volt on-board network. Installation of the blocker on trucks and buses that use a 24-volt power supply is not allowed. The device uses the block principle of signal encryption, and the key length for data transmission is 64 bits. The blocker is compatible with many Pandora signaling models. The cost of the device is 3000 rubles.
2. Starline R4. The device, made in a small housing, is designed for hidden installation in a harness with standard car wiring. The module is equipped with all the necessary elements that will provide control of the hood lock and hidden blocking of the power unit. The control procedure is performed via a single-wire digital line. If the car is equipped with an anti-theft system, before purchasing it is necessary to clarify the possibility of connecting the blocker to a specific model of the alarm system. Since the device is controlled via a single line, the consumer does not need to extend additional wires into the cabin. The code blocker provides the ability to control the hood limit switch, as well as activate the ignition system. The cost of the device is 2200 rubles.
3. Collection Standard. The domestically produced device is characterized by the presence of normally closed contacts. The current the blocker operates with is 10 amperes. A dynamic communication channel is used for control. The device is made in a small-sized case, which ensures ease of installation anywhere in the cabin. To detect the blocker, the criminal will have to check all the cables in the car. If an unauthorized attempt is made to start the engine, the contact elements are unlocked, which leads to the blocking of the internal combustion engine. The price of the device is 2950 rubles.
4. Pandect IS-125. The device was developed by the manufacturer AlarmTrade specifically for use in cars equipped with alarms. The lock is also compatible with other anti-theft systems and new immobilizers. The device is installed in the engine compartment; the blocker is connected to the microprocessor module via a radio signal. Conversational encoding is used to transmit data; all information is transmitted in the range from 2.4 to 2.5 GHz. The device is protected from short circuits and is energy efficient. The cost of the device is 3300 rubles.

How to turn a “minus” into a “plus” and vice versa? How to hook up to an electric drive? How to open the trunk with the alarm key fob? How to block the engine from starting? There is an answer to all these questions: using a relay.

Knowing how a relay works, you can implement various connection schemes to the car's electrical wiring.

Usually relay has 5 contacts (there are also 4-pin and 7-pin, etc.). If you look at relay carefully, you will see that all contacts are signed. Each contact has its own designation. 30, 85, 86, 87 and 87A. The figure shows where and what contact is.

Pins 85 and 86 are the coil. Contact 30 - general contact, contact 87A is a normally closed contact, contact 87 is a normally open contact.

At rest, i.e., when there is no power to the coil, contact 30 is closed with contact 87A. When power is simultaneously supplied to contacts 85 and 86 (one contact is “plus” and the other is “minus”, no matter where it is), the coil is “excited”, that is, it is triggered. Then contact 30 is disconnected from contact 87A and connected to contact 87. That’s the whole principle of operation. It seems to be nothing complicated.

A relay often comes to the rescue during installation additional equipment. Let's look at the simplest examples of using relays.

Engine lock

The blocked circuit can be anything, as long as the car does not start if the circuit is broken (starter, ignition, fuel pump, injector power, etc.).

We connect one coil power contact (let it be 85) to the alarm wire, on which a “minus” appears when arming. We apply +12 Volts to the other contact of the coil (let it be 86) when the ignition is turned on. Contacts 30 and 87A are connected to the break in the blocked circuit. Now, if you try to start the car while the security is on, contact 30 will open with contact 87A and will not allow the engine to start.

This scheme is used if you have a “minus” from the alarm to blocking when arming. If you have a “minus” from the alarm to blocking when disarming, then instead of contact 87A we use contact 87, i.e. the circuit break will now be on pins 87 and 30. With this connection relay will always be in working condition (open) when the engine is running.

We invert the polarity of the signal (from “minus” we make “plus” and vice versa) and connect to low-current transistor alarm outputs

Let’s say we need to get a “minus” signal, but we only have a “positive” signal (for example, a car has positive limit switches, but the alarm system does not have a positive limit switch input, but only a negative input). The relay comes to the rescue again.

We apply our “plus” (from the limit switches of the car) to one of the coil contacts (86). We apply “minus” to the other contact of the coil (85) and to contact 87. As a result, at the output (pin 30) we get the “minus” we need.

If, on the contrary, we need to get a “plus” from a “minus,” then we slightly change the connection. We apply the initial “minus” to contact 86, and apply “plus” to contacts 85 and 87. As a result, at the output (pin 30) we get the “plus” we need.

If we need to make a good powerful “ minus" or "plus", then we also use this scheme.

We supply the alarm output to pin 85. We apply “plus” to pin 86. We apply a signal of the polarity that we need to receive at the output to pin 87. As a result, on pin 30 we have the same polarity as on pin 87.

Opening the trunk using the car alarm key fob

If your car has an electric trunk drive, you can connect to it with a car alarm to open it using the alarm key fob. If the alarm outputs a low-current signal to open the trunk (and most often this is the case), then we use this circuit.

First of all, we find the wire to the trunk drive, where +12 Volt appears when the trunk is opened. Let's cut this wire. We hook up the end of the cut wire that goes to the drive to pin 30. We hook up the other end of the wire to pin 87A. We connect the alarm output to contact 86. We connect contacts 87 and 85 to +12 Volts.

Now, when a signal is sent from the alarm to open the trunk, the relay will work and “plus” will go to the trunk electric drive wire. The drive will operate and the trunk will open.

These are just a few wiring diagrams using relays. You can find a few more schemes using relays on the website in the category

In this article, I will try to highlight the issues related to proper engine blocking, not from the point of view of the correctness of electrical circuit breaks in the car, but from the point of view of the theft resistance of the blocking systems themselves, that is, we’ll talk about how to get the maximum out of an ordinary alarm system in terms of blocking. But first, some necessary clarification on the topic - for most, the history of the issue may be useful.

So, as you know, a modern car alarm has two important functions, which is why they are actually bought and installed on a variety of cars. Important - I mean - in terms of counteracting theft, as well as from the point of view of protection against looting. The first function is to directly notify the owner and others about such attempts, and the second is to prevent, well, let’s put it bluntly, unauthorized starting of the engine, or, in other words, the start blocking function. Let’s talk about it, about blocking, in more detail.

It just so happened historically that the vast majority of alarms use relays as actuators. This is probably why the motto of hijackers of all times and peoples today sounds like this: “Cherche la relay.” Blocking relays can be built into the alarm module, or the alarm has special pins on the connector to control such a relay. Or very small, but high-quality and powerful relays are placed in the housing of a standard automotive relay (as can be seen in the photograph, Fig. 1), Fig. 1 together with a control circuit that carries out switching according to coded commands coming from the alarm unit either through a special wire or without a wire at all, and through switched circuits in the form of a high-frequency coded signal. It is clear that with the help of such “stuffed” relays it is possible to organize the most secretive and difficult to neutralize locks today, because their presence in the car does not reveal anything, and car thieves must be highly qualified in order to find such small bugs in modern car, literally stuffed with various electrical devices and cables. However, alarms that can control wireless relays are much more expensive than the ubiquitous simple systems with ordinary relay interlocks. But if you have the means to protect your car from theft, preference should be given to such expensive systems, because the developers with this beautiful solution were able to give installers a fairly effective solution to combat theft - a locking relay controlled via the car’s standard wiring (or even via radio). .

Why? Because a regular standard-installed alarm system will not be able to resist hijackers for more than a few minutes. And the reason lies not only in the standardization and predictability of the “mass installation”, but also in the fact that the developers themselves did not pay enough attention at the time to the important function of blocking the engine; they even came up with an offensive name for it - “auxiliary”. “Well done,” of course, what can you say - one built-in relay or even just one wire - that’s all that is allocated by them to implement this, which is still far from auxiliary, but the same basic signaling function, along with notification.

Well, let’s see what can be done to correct the situation with “little loss.” To “take a look,” however, you need to have a good idea of ​​what engine blocking algorithms are used in modern car security systems.

And they - these algorithms - can be passive or active. Everything is the same as with well-known “minorities” - like relays and relays - and lo and behold - it can be “passive”, or maybe “active”. It depends on the algorithm (like, on the environment, on upbringing - who will become who and what). The active blocking algorithm is the most vulnerable, because the blocking relay with such an algorithm in a de-energized state allows the engine to start. This type of blocking is otherwise called “normally closed”, or simply NC - according to the type of blocking relay contacts in the “Security” mode. A typical scheme for implementing NC engine blocking is illustrated by the fragment of the connection diagram for a standard Taiwanese alarm system shown in Fig. 2 - mostly manufacturers who have narrow eyes from birth like to use NC blocking. In the “Disarmed” mode, there is no voltage on the blocking terminal, and therefore on the relay winding, and the relay, with its NC contacts (contacts 87a and 30), allows the engine to start. More precisely, it does not prevent this. In the “Security” state, there is a ground potential on this wire, and when you try to start the engine, a plus from the ignition switch will appear at the second end of the winding, the relay will switch, thus prohibiting the operation of the starter, in this example.

To neutralize active blocking, obviously, it is enough to simply de-energize the alarm module in any way. For example, by pulling out all the connectors from the module, or simply breaking the wires, and often it is enough to remove the system fuses from the holders. And that's all - nothing can stop you from starting the engine. This is the main reason why I can’t stand blocking NC by relay contacts.

With a passive algorithm, a blocking relay prohibits engine operation in a de-energized state; the contacts of such a relay are normally open (blocking is therefore called NR). This means that to remove the lock, you need to apply voltage to the relay, it will switch, and the engine can be started. In Fig. Figure 3 shows an example of a standard blocking of an injection engine fuel pump by an alarm.

As can be seen from the diagram, the blocking relay breaks the control circuit of the standard fuel pump relay, so the current through its contacts is small, which allows the use of a low-power, and therefore small-sized relay. At the same time, the theft resistance of such a simple blocking is low - it is usually bypassed by applying voltage directly to the fuel pump using a jumper. You can slightly improve the quality of blocking by adding another blocking relay (Fig. 4), breaking the power supply wire of the pump with its contacts. In this case, it is advisable to partially remove the standard power wire, laying your own wire in its place - you will get a so-called “spaced” blocking - it will be even more difficult for scoundrels to repair the break. Especially if the second relay is installed directly in the fuel pump hatch, as illustrated in photographs 5, 6, 7 and 8.

Rice. 4. A resistor is used to make it difficult to diagnose a “fault” (specifically, here it is more to illustrate the principle), but diodes are needed so that a short to ground of the blocking wire directly at the relay does not turn off the entire blocking.

Rice. 5. The photo shows the fuel pump connector and its supply cable. The blocking relay breaks the power wire, and applying voltage using a jumper to the wires in the cabin will not have any effect - you will need to unscrew the fuel pump hatch cover, and we can use non-standard screws to make this more difficult.

Rice. 6. The relay is carefully hidden under the bottom of the trunk, so that after installing the cable in place, the relay would not be visible.

Fig.7. The cable is in place - but where is the relay?

Rice. 8. After screwing the lid back on, it is not easy to guess about the “bug” living under it.

The most important advantage of the HP blocking is that even if you de-energize the alarm using the above methods, this will not help - to neutralize it, it is already necessary not only to de-energize the system, but also to connect the blocking output of the alarm to ground. To make things even more difficult for hijackers, the developers integrate a blocking relay inside the alarm module. An example of such a blocking is shown in Figure 9 - the built-in relay breaks the high-current power supply circuit of the fuel pump - and to bypass the blocking in this case it is necessary to restore the break.

Thus, it is easy to see that the HP lock is better at resisting thieves - they must find the necessary wires in the alarm harness and connect them together. Or find the ground wire on the alarm connector, disconnect it and connect the remaining wires together. In general, this is already more complicated than tearing the alarm unit out of its connectors. But it's still simple.

Well, it’s clear with NC blocking - but what to do if the alarm system has an active algorithm for blocking NC with relay contacts. Such questions often arise from those who would like to modify the existing Taiwanese alarm system in order to add protective properties to it “at an inexpensive price.” There is a way out, but for this you need to install a transistor inverter switch into the alarm module. It is best to make the blocking relay itself remote, and implement the winding switching circuit so that 12 volts must be supplied to one end and ground potential to the other. Then twisting all the wires into one pile, or even just two control wires, will do nothing! The engine will remain locked.

A diagram of such a modification is shown in Figure 10.

Typically, in standard alarm systems, the output to NC blocking is taken from the output of a buffer microcircuit (ULN2003A - for example), sometimes, apparently, just in case, the developer adds a diode or low-resistance resistance in series - especially if a transistor switch is used instead of a buffer microcircuit, or an output to the lock is taken directly from the processor. A low-resistance resistor or diode plays the role of a kind of fuses; they must be removed during modification.

The photograph in Figure 11 shows, as an example, an alarm board in which the blocking output is taken directly from the “leg” of the microcircuit (marked with a red arrow) - in this case, you will have to cut the track on the board. Resistance R2 is selected for reasons of optimal current consumption - however, there is no need to get carried away - after all, the load in the collector circuit of the transistor will be the relay winding, and it depends on the type of relay - what current is needed for the transistor to saturate in open state, and, accordingly, the resistance value in the base depends on this. Suitable for most cases compound n-p-n transistors with the corresponding relay type load current. Naturally, the key converts the blocking algorithm from active NC to passive NO - when the microcircuit is “minus in security” - the transistor is closed, the relay is de-energized, and the engine is blocked. It is advisable to connect the second end of the blocking relay to the “Ignition” wire so that the relay is not energized when the alarm is turned off for some reason and when the engine is not running. However, if the second end of the relay winding is connected to the “Ignition” directly inside the alarm, and even through a diode, as shown in the diagram, then the thief’s task will become even more complicated - it will no longer be enough to find the wires for blocking and connect them together or to ground - you will need to submit a plus for one of them, and a minus for the other, and this is already a 50 to 50 lottery. At one time, this simple idea was “instilled in me” by Grigory, aka GrishaTav. This scenario can occur when the thief first turns off the power to the alarm system (but it didn’t work), then tries to disconnect the connectors and find the exit to the blocking (usually an orange or yellow wire) - again a mistake, then there will probably be attempts to alternately connect all the “suspicious” wires to mass - time, in a word, all this takes more time. And this is our goal - to maximize the time required for theft. For this, you can use not one, but several blocking relays connected according to the described algorithm - each such relay will significantly complicate the task of starting the engine for possible car thieves, and, of course, the likelihood for them to be caught at the crime scene will increase. We can work slowly, and our cause is just, and the enemy will be defeated - after all, God himself told us to think again and again - what we could do... good for our car, in order to further protect it from theft.

Photo in fig. 12 - illustrates one of the examples of the implementation of this modification in real life - additional elements are successfully placed in place of the soldered light alarm relay (which is soldered and mounted remotely because its characteristic “clicking” of contacts during an alarm is an unmasking factor). The blue wire is an additional wire to the second end of the relay coil

As you can see, with properly “sharpened” hands, adding just a transistor and a resistor and a couple of wires to the alarm is a very simple task - the main thing is to have a good understanding of the operating principle of the described algorithms.

In a similar way, you can modify alarms with a passive HP algorithm using relay contacts - in this case, a transistor switch is obviously not required. And if the developer took care of a more restful sleep for the owner’s car and built a blocking relay inside the alarm module, then you can increase the number of additional remote relays “as your heart desires” - and then you get the concept of “alarm + immobilizer” in one bottle - and only at the expense additional relays and properly organized interlocks.

Well, well, many will object to me, but you have to unscrew the case, pick up a soldering iron, carefully mount the elements, often cut the tracks on printed circuit board— in general, this technology, I agree, is not for everyone. Yes, and with the warranty on the module, problems are inevitable. More important point Another one - although after the described modifications it is more difficult, it is still possible to bypass the blocking relay - they are still connected to the alarm module.

What if you use polarized rather than simple relays as blocking relays?! The photographs (Fig. 13 and 14) show several cool examples of such a relay. For comparison, photo 13 also shows an ordinary car relay (on the left) and the radio relay mentioned somewhere at the beginning of the article along with a two-button control panel. Isn't it true - the dimensions of polarized relays are very small. The most pleasant relay for our purposes, SDS S2-L-12V, has four contact groups (two NC and two NO) and two stable states. And now about the main advantage of these relays - they switch from one stable state to another only when the polarity of the voltage supplied to the winding changes! This is an interesting property and allows you to organize a unique blocking approaching in its properties the coded blocking relays mentioned at the beginning of the article, which are so far used mainly in expensive security systems. And what’s most important is that the blocking described below can be implemented for any alarm! Essentially this is a secret device, but controlled by the main alarm module.

Let's look at a few typical examples of the use of “little helpers”.

Example 1. A polarized relay is connected to the power outputs for controlling door actuators. By the way, I am often asked to draw the most detailed connection diagrams for illustration, with numbering of contacts, for a specific type of alarm, and in general - to explain everything in as much detail as possible. But in this example, the diagram is so elementary that let me not give it - but limit myself to a description of the principle. Namely, when the door locks are closed, the relay is in the “locked” position, when open, the “lock is removed”, that is, the winding of the polarized relay is simply connected in parallel to the door activators, because the relay and an ordinary Taiwanese motor are very similar - the same two stable states and switching by changing the polarity of the control pulse. Only the relay is not afraid of constant voltage on the winding, and you cannot switch it from one state to another by hand, like a motor.

It is clear that twisting the wires together here, as in the other examples below, will not remove the lock. Intervention in the signaling circuit is not required, the guarantee is maintained. Disadvantage - without an additional relay, it is impossible to use such a function of many alarms, which is convenient for some, as closing the car door locks while driving. This, I must say, is also a popular topic - how to attach door actuators to the low-current alarm output for the central locking control, how to organize the connection of additional sensors and a pager transmitter for power supply, and in our case - how to connect an additional engine lock if you want the doors While driving, would the cars be locked for safety by an alarm command? Well, Figure 15 shows a detailed diagram of how this is implemented in practice. At the same time, as an example of “flexibility of thinking,” the more common two-winding relay (RPS28B, RPS34, RPS36, etc.) was taken as a polarized relay - for these types of relays, switching is carried out by applying a control pulse to the corresponding winding, and not by changing the polarity of the control pulse. However, this circumstance does not at all prevent us from using such relays for our purposes.

Figure 15. Using a polarized relay for switching additional actuators and for additional engine blocking.

A few explanations about the diagram. Negative impulses are sent from the alarm output to the relays that control the door locks. The polarized two-winding relay is also controlled by the same pulses, so that when the alarm closes the doors, the relay switches to the locking position (the diagram simplifies only one group of polarized relay contacts, in fact there are usually more of them). When the doors are opened, the lock is also released. To ensure that while driving, closing the doors at the alarm command does not lead to engine blocking, an additional relay is used that breaks the control circuit of the polarized relay along the blocking winding when the ignition is turned on.

Example 2. The alarm system has two unused additional channels for controlling external devices - upon command from the key fob at the additional terminals. channels, negative pulses are generated, switching the polarized relay into the “blocked” and “unblocked” states. This, in general, rare option is shown in the circuit diagram in Fig. 16, with the necessary explanations. Although here it is better to act according to the situation, depending on the capabilities of the security system at your disposal. For example - the alarm system has an output for the “Comfort” function, when the windows are additionally closed when arming - OK, we use this impulse to activate the relay - with each arming the relay will switch along with the windows being raised, and our car will receive an additional lock at a cost several relays, one of which is very tricky. By the way, to control it, due to the low current consumption (less than 10 milliamps), you can directly use the alarm output, intended for active blocking.

Your alarm system has an output for remotely opening the trunk, or a hood lock, which usually works in the “disarmed” mode - great - you can use the output of such a channel to unlock the relay and, accordingly, the engine. At the same time, if you are smart and entrust the important task of turning off the relay to the car’s standard buttons or a convenient suitable combination of them, you will get a lock that cannot be disconnected from the alarm! Buttons can be very different - there are quite a lot of them in the car - for example, buttons for power windows or control mirrors. It could also be the parking brake switch, or the brake pedal switch, or the reverse speed sensor, or the button for turning on the heated rear window, or the low/high beam switch lever, or the washer button, - finally, - the buzzer (joke) - who knows where else you can “obtain” the necessary “on demand” 12 volts in the interior of the protected car! The options can be very different - it is only important to weed out the frankly inconvenient ones or those that can be noticed from the street - for example, if the ignition is on, then when you press the brake pedal the brake lights will light up - this can be seen from the outside and figure out how to turn off the “secret toggle switch” in such a car.

But what if the alarm system does not have enough additional channels, and additional manipulations with the standard buttons are not desirable (not everyone likes to start the engine of their car in “two slams, three slams” every time). This case is illustrated by the following example (Fig. 17). Here, one end of the relay winding is switched ... by the alarm output to the siren (the siren, by the way, can control not only the blocking, with the help of this output you can even “teach” the door alarm to open separately, as Yuri Gnatyuk from Arkhangelsk did in his time , aka Jora - he lives here http://jora.by.ru, and here he talked about using the siren output “for other purposes” http://www.auto.ru/wwwboards/stealings/0034/9289.shtml ).

The relay is turned off (in our example) by an additional alarm channel. It turns out to be an interesting algorithm of operation, based on a convenient and useful feature of most alarms, which is called complexly - “silent arming/disarming” or, in other words, without sound confirmation signals from the siren. That is, with a quiet setting, our cunning, really main relay will not be activated, and if we also “quietly” disarm the alarm, the relay will continue to “sleep”. However, any alarm can “wake up” him, or rather, the very first alarm trill of a siren. The siren, by the way, can go off not only in “security” situations, but also during a robbery attack - and thus a new, unexpected and even “polarized” line of engine protection will appear in front of the robbers - called “try to start it.”

Of course, the second, unlocking end of the “tricky” relay can also be connected to the already described combination of standard buttons, which - this is important - will no longer have strict restrictions on the ease of regular use - because now this will have to be done much less often. For example, when parking in an unfavorable area or for a long time, it is better to set the alarm to “security” with “sound” - it will be calmer. And for a short-term stop, you can also rely on sensors - which, by definition, are required to provide at least one “crack” of the siren. If nothing happened while the car was under alarm protection, then the owner of the car turns off the system in the same silent way, sits down and goes about his business. If there was an alarm, the relay will immediately switch to the “blocked” position, and no manipulation of the alarm will help switch it back - you will need to use the “two slams, three slams” method known only to the owner. But this is no longer annoying as in previous versions, because with correctly adjusted sensors, false alarms rarely occur. Well, if there are no false alarms, due to the additional line of protection there is a chance to stay with the car.

And so, with unhurried explanations, we slowly reached the end of the edge of our “savvy.” We throw out the extra relays (which also need to be shunted with diodes “just in case” - and this requires time and money during installation, extra connections appear that reduce reliability, etc.), and what remains is this simple “obscenely” The diagram in Fig. 18 is an original solution, isn’t it?! The characteristics of “cunning” relays allow them to do just fine without their ordinary “clattering” contact counterparts. One end turns out to be connected to ground through the resistance of a conventional non-autonomous siren (a fuse (or diode) connected in series with the siren protects the alarm output to the siren - after all, now this output has the important task of activating the “sleeping” interlock). The second end “sits on ground” through an additional penny resistance of 100 Ohms, since the resistance of the relay winding is a kilo-ohm or more. How the scheme works is elementary, dear Watsons. The relay is activated by any siren signals - including service ones, this has already been described. And it is turned off by a reed switch, through the contacts of which 12 volts are supplied to the second winding of the relay at the moment we need. I moved the magnet of the reed switch to the desired place on the casing, and the siren would quietly “say” - everything is in order, the relay has turned off, and feel free to start the engine. You can also take a reed switch with switching contacts - they are just less common, but a regular NC reed switch (this is a NC reed switch when paired with a magnet, and without a magnetic counterpart its state is as in the diagram - normally open) and a resistor are sold everywhere. Where to hide the reed switch in the car is not a problem - they are so small that you can choose and hide it anywhere - right down to the horn, and this is no longer a joke.

Thus, the use of such relays - relatively cheap, but very suitable for, I’m not afraid of this word - the sacred task of worthy of blocking OUR car - a serious bid for victory in the fight against car thieves - after all, a ghost lock, as you can call it, does not turn off, even if the entire alarm subject is found, and, at the same time, practically does not bother you in everyday use. The reliability of the relay, of course, is higher than that of complex microprocessor devices, and this makes it absolutely unnecessary, in order to exclude warranty claims, to provide for “emergency” bypass of locks - it’s no secret that car owners, if something happens to the engine, the first thing they do is sin to the alarm. And of course, in such cases, they often don’t remember what they were shown on the service to disable the blocking. And in the case of using polarized relays, the user himself turns them off periodically, and this circuit can fail only due to poor installation, which in itself is nonsense - it’s the same as poorly screwing the ground on the alarm. What’s especially nice is that the dimensions of polarized relays are much smaller than those of such serious competitors as Hook-Up relays, which allows them to be wound directly into bundles, making the task of detecting them difficult to accomplish in practice.

What's in the harnesses - for those who have right hands and who likes original non-standard solutions - the last illustration (Fig. 19) in this article is a blocking relay placed in the housing of a regular autonomous siren. The calculation is simple - a valuable item is often most difficult to find if it is in a visible place. The first thing the hijacker will do is “damage” the painfully familiar siren, cut off its wires, and thereby make it even more difficult for himself to start the engine. Would it ever occur to anyone that a relay could live in the body of a standard siren? But she is both warm and dry there - except that it is loud at times. Let's hope that she, the little one, is deaf from birth.

And the hijackers will only have the opportunity to try themselves in the field of “bypassing” these little bugs, but we will talk, I hope, in the next article about how to prevent them from doing this specifically and inexpensively.

Annex 1.
Short review domestic standard relays in housings as shown in the photograph below.

Below you will find information from one manufacturer; there are other manufacturers and foreign analogues. For this part of the article, the main thing is to make it clear to the average car enthusiast that relays can be interchangeable, have different circuits, different numbers of contacts, depending on their purpose.

Domestic relays of this series mark the normally closed contact as 88. In imported relays this contact is everywhere called 87a

Typical relay circuits. Tsokolevka.

Scheme 1

Scheme 1a

According to scheme 1, the following 5-contact (switching) relays are produced:

With 12V control - 90.3747, 75.3777, 75.3777-01, 75.3777-02, 75.3777-40, 75.3777-41, 75.3777-42

With 24Volt control - 901.3747, 901.3747-11, 905.3747, 751.3777, 751.3777-01, 751.3777-02, 751.3777-40, 751.3777-41, 751.3777-42

According to scheme 1a with an anti-interference resistor:

With 12V control - 902.3747, 906.3747, 752.101, 752.3777, 752.3777-01, 752.3777-02, 752.3777-40, 752.3777-41, 752.3777-42

With 24Volt control - 903.3747, 903.3747-01, 907.3747, 753.3777, 753.3777-01, 753.3777-02, 753.3777-40, 753.3777-41, 753.3777-42

Scheme 2

Scheme 2a

According to scheme 2, the following 4-pin (closing/closing) relays are produced:
With 12V control - 90.3747-10, 75.3777-10, 75.3777-11, 75.3777-12, 75.3777-50, 75.3777-51, 75.3777-52, 754.3777, 754.3777-01, 754.37 77-02, 754.3777-10, 754.3777-11, 754.3777-12, 754.3777-20, 754.3777-21, 754.3777-22, 754.3777-30, 754.3777-31, 754.3777-32

With 24Volt control - 904.3747-10, 90.3747-11, 901.3747-11, 905.3747-10, 751.3777-10, 751.3777-11, 751.3777-12, 751.3777-50, 751.3777-5 1, 751.3777-52, 755.3777, 755.3777-01, 755.3777-02, 755.3777-10, 755.3777-11, 755.3777-12, 755.3777-20, 755.3777-21, 755.3777-22, 755.3777-30, 755.3777-31, 755.3 777-32

According to scheme 2a with an anti-interference resistor:
With 12V control - 902.3747-10, 906.3747-10
With 24Volt control - 902.3747-11, 903.3747-11, 907.3747-10

Scheme 3

Scheme 3a

According to scheme 3, the following 4-contact (breaking/switching) relays are produced:
With 12V control - 90-3747-20, 904-3747-20, 90-3747-21, 75.3777-20, 75.3777-202, 75.3777-21, 75.3777-22, 75.3777-60, 75.3777-602, 75 .3777-61, 75.3777-62

With 24Volt control - 901-3747-21, 905-3747-20, 751.3777-20, 751.3777-202, 751.3777-21, 751.3777-22, 751.3777-60, 751.3777-602, 751.377 7-61, 751.3777-62

According to scheme 3a with an anti-interference resistor:
With 12Volt control - 902-3747-20, 906-3747-20, 902-3747-21, 752.3777-20, 752.3777-21, 752.3777-22, 751.3777-60, 751.3777-61, 62,

With 24Volt control - 903-3747-21, 907-3747-20, 753.3777-20, 753.3777-21, 753.3777-22, 753.3777-60, 753.3777-61, 753.3777-62,

ATTENTION!!!
Relays of the 19.3777 series have a housing similar to the one above. The circuit of these relays has protective and decoupling diodes. Such relays have a polarized winding. These relays are not mentioned here in the article because they have limited use.

Relays of modern cars.

Differences and variety of relay numbers mean different mountings, housing design, degree of protection, coil control voltage, switched currents and other parameters. Sometimes when choosing an analogue it is necessary to take into account some parameters.

According to scheme 5, the following 4-contact (closing/closing) relays are produced:
With 12V control - 98.3747-10, 982.3747-10
With 24V control - 981.3747-10, 983.3747-10

According to scheme 5a with an anti-interference resistor:
With 12V control - 98.3747-11, 98.3747-111, 982.3747-11
With 24V control - 981.3747-11, 983.3747-11

Relay

Relays are often used when installing security equipment.

The relay consists of two main parts - a winding with a core (electromagnet) and a group of contacts. Both of these parts are combined in one housing. When voltage appears on the winding, one of the relay contacts is attracted to the electromagnet and closes with the other. At the same time, an opening with the third contact can occur.

Based on the type and number of contacts, relays can be divided into several groups.

1. Relay with normally open contacts. In the initial state, the output contacts are open, no current flows through them. When the relay is activated, the contacts close, and the circuit in which the relay is connected begins to flow. electricity. This type of contact is called HP (normally open). In English literature it is designated NO (normally-open).

3. The contact can be a changeover contact. In the initial state, one of the two circuits is closed; after the relay is activated, the first circuit is broken, and the second is closed. Such a relay has one common contact for two circuits, that is, the circuits are not independent. In English terminology - CO (change-over) or DT (double-throw).

Basic relay parameters that you need to know for the right choice when installing security equipment:

The permissible current that the relay can pass through its output contacts;

Type of output contacts (NO, NC, switching), number of these contacts;

Relay current consumption, operating voltage;

Dimensions (which is especially important for performing invisible blocking).

Let's try to understand these parameters in more detail.

The permissible current supplied to the contacts is determined both by the dimensions of the relay itself and the materials used in it. For example, in expensive relays the contacts are placed in a sealed capsule filled with an inert gas. This allows you to prevent contact oxidation and increase its reliability. If you choose the wrong relay based on power, then there is a high risk that at the most crucial moment it will fail and damage the vehicle’s equipment. For example, exceeding permissible switching currents can lead to a short circuit, and exceeding control currents can lead to a fire.

To control several circuits independent of each other at the same time, there are relays that have not one pair of contacts, but two or more.

The type of output contacts is determined based on which circuit needs to be blocked and at what point in time. For example, you need to open the trunk on command from an additional alarm output. The power of the additional channel is not enough to directly connect it to the trunk activator. Therefore it is necessary to use a relay. In order for the relay to close the activator power circuit only when a control pulse appears at the additional alarm output, it is necessary to use a relay with a pair of normally open contacts. It will work like this: in the initial state there is no control signal, the relay is de-energized, the activator circuit is open. As soon as a pulse appears, the relay closes the output contacts, current flows through the activator, and the lock opens.

Current consumption is also important, because a relay that is incorrectly selected for this parameter can drain the battery in a short time. For example, when installing an alarm system, an additional engine blocking was made using a conventional automotive 4-pin relay. When armed, it turns on and breaks some significant circuit (for example, a fuel pump wire). However, when turned on in this way, current will flow through the relay winding. Although this current is small (approximately 0.05 - 0.1 A), 2 - 3 such blockages can drain all the energy from the battery in less than 3 weeks of inactivity.

IN in this case a different blocking circuit should be used (the relay will break the protected circuit only when the ignition is turned on).

Relays can be divided into non-polarized and polarized. A non-polarized relay is usually large in size, consumes more current and is capable of switching a larger load.

For example, a typical automotive non-polarized relay draws 0.1 A of current and is capable of switching currents up to 40 A.

A polarized relay has two stable states and consumes current only at the moment of switching. This relay can switch up to 10 A. Now polarized relays are rarely used; in most cases they can be replaced with logic chips.

When triggered, self-induction current surges occur in the windings of large relays, which can be quite significant. To prevent these surges from causing malfunctions in the alarm system, it is strongly recommended to shunt the winding of any relay with a diode, that is, solder a rectifier diode between two input contacts so that the anode of the diode is

connected to ground, and the cathode to the contact on which the plus appears. In this case, the diode will not affect the control signal, since with reverse voltage the diode resistance is very high. When an inductive surge occurs, all the current will pass through the diode and will be extinguished by it.