Car alarm system on one chip k561la7. Security alarm

Figure 2 shows a diagram of a simple time relay with LED indication. Time counting begins at the moment the power is turned on by switch S1. At the very beginning, capacitor C1 is discharged and the voltage on it is low (like a logical zero). Therefore, the output D1.1 will be one, and the output D1.2 will be zero. LED HL2 will be lit, but LED HL1 will not be lit. This will continue until C1 is charged through resistors R3 and R5 to a voltage that element D1.1 understands as a logical one. At this moment, a zero appears at the output of D1.1, and a one appears at the output of D1.2.

Button S2 is used to restart the time relay (when you press it, it closes C1 and discharges it, and when you release it, charging C1 starts again). Thus, the countdown begins from the moment the power is turned on or from the moment the S2 button is pressed and released. LED HL2 indicates that the countdown is in progress, and LED HL1 indicates that the countdown has completed. And the time itself can be set using variable resistor R3.

You can put a handle with a pointer and a scale on the shaft of resistor R3, on which you can sign the time values, measuring them with a stopwatch. With the resistances of resistors R3 and R4 and capacitance C1 as in the diagram, you can set shutter speeds from several seconds to a minute and a little longer.

The circuit in Figure 2 uses only two IC elements, but it contains two more. Using them, you can make it so that the time relay will sound a sound signal at the end of the delay.

Figure 3 shows a diagram of a time relay with sound. A multivibrator is made on elements D1 3 and D1.4, which generates pulses with a frequency of about 1000 Hz. This frequency depends on resistance R5 and capacitor C2. A piezoelectric “tweeter” is connected between the input and output of element D1.4, for example, from an electronic watch or a handset, or a multimeter. When the multivibrator is working it beeps.

You can control the multivibrator by changing the logic level at pin 12 of D1.4. When there is zero here, the multivibrator does not work, and the “beeper” B1 is silent. When one. - B1 beeps. This pin (12) is connected to the output of element D1.2. Therefore, the “beeper” beeps when HL2 goes out, that is, the sound alarm turns on immediately after the time relay has completed its time interval.

If you don’t have a piezoelectric “tweeter”, instead of it you can take, for example, a microspeaker from an old receiver or headphones or telephone. But it must be connected through a transistor amplifier (Fig. 4), otherwise the microcircuit can be damaged.

However, if we don’t need LED indication, we can again get by with only two elements. Figure 5 shows a diagram of a time relay that only has an audible alarm. While capacitor C1 is discharged, the multivibrator is blocked by logical zero and the beeper is silent. And as soon as C1 is charged to the voltage of a logical unit, the multivibrator will start working, and B1 will beep. Figure 6 is a diagram of a sound alarm that produces intermittent sound signals. Moreover, the sound tone and interruption frequency can be adjusted. It can be used, for example, as a small siren or apartment bell.

A multivibrator is made on elements D1 3 and D1.4. generating audio frequency pulses, which are sent through an amplifier on transistor VT5 to speaker B1. The tone of the sound depends on the frequency of these pulses, and their frequency can be adjusted by variable resistor R4.

To interrupt the sound, a second multivibrator is used on elements D1.1 and D1.2. It produces pulses of significantly lower frequency. These pulses arrive at pin 12 D1 3. When the logical zero here, the multivibrator D1.3-D1.4 is turned off, the speaker is silent, and when it is one, a sound is heard. This produces an intermittent sound, the tone of which can be adjusted by resistor R4, and the interruption frequency by R2. The sound volume largely depends on the speaker. And the speaker can be almost anything (for example, a speaker from a radio, a telephone, a radio point, or even a speaker system from a music center).

Based on this siren, you can make a security alarm that will turn on every time someone opens the door to your room (Fig. 7).

Prologue

Another multivibrator is assembled on elements DD1.3 and DD1.4, the operating frequency of which is about 1 kHz. Timing circuit – C3, R3. The diagram was taken from the 11th leg of the microcircuit when the multivibrator was working constantly.

When pulses with a repetition rate of 3 Hertz appear on the 4th leg, an intermittent signal with a frequency of 1 kilohertz appears at the output of DD1.4 (11th leg). The diagram was taken from the 11th leg when the alarm was triggered.

Output DD1.4 is connected to transistor switch VT1, which controls the operation of speaker Ba1. Here a compound transistor with a high current gain is used. If you don’t have such a transistor at hand, you can replace it with a homemade compound transistor.

Potentiometer R4 allows you to set the optimal siren volume level.

Resistors R5, R6 limit the output current of the microcircuit. It is advisable to choose a resistance of these resistors of at least 1 kilo-ohm for each volt of supply.

Resistors R7 and R8 limit the LED current. And the main current consumption in standby mode also depends on the resistance of resistor R8.

Capacitor C1 protects the input circuits of the microcircuit from interference that can be induced into the circuit by electromagnetic radiation.

Protective diodes VD1 and VD2 protect the circuit from a powerful electrical impulse that can be caused by lightning. In this case, fuse FU1 can protect the loop from breaking, although not always.

Capacitors C4 and C5 – power filter.

The supply voltage of this security device can be selected in the range of 6… 12 Volts. You can use several AA, AAA elements connected in series or a 9-Volt Krona battery.

Energy consumption when the siren is activated depends on the volume level set by potentiometer R4, and at maximum volume, on the resistance of the dynamic head Ba1. Consumption in standby mode is mainly determined by the resistance of resistors R1 and R8.

But, if, to save battery energy, resistor R8 can be eliminated altogether along with LED VD4, then it is undesirable to significantly increase the resistance of resistor R1, especially if the wire length is 100 meters or more.

The circuit of this security alarm is designed to work with a break-type sensor. A thin enameled copper wire such as PEV, PEL and the like is used as a sensor. The wire diameter is selected based on the following considerations. The thinner the wire, the more likely a false alarm is, but also the less likely it is that an intruder will notice it or feel it when touched. So, you should choose in the diameter range of 0.05... 0.1 mm. A calmly walking person may not feel a break in a wire with a diameter of 0.05 mm even with an open part of the body. But it will be difficult not to break such a wire during installation. To lay a thin wire, you can use a light coil rotating in bearings.

The operation of the security system was tested on this mock-up.

A drawing of a printed circuit board based on one of the widely used types of breadboards.

How it works? Open the screen and select the resolution 1280x720px.

Schematic diagram of simple security devices with alarms. made on K561LA7 microcircuits. This alarm system can protect a passenger car or a room, the difference in the scheme is quite insignificant.

In the first case, automotive door contact sensors, as well as a hood and trunk sensor, are used as sensors, and in the second case, a standard reed door position sensor is used.

In both cases, the “key” to block the alarm is a key fob with a magnet inside, which must be brought to a hidden reed switch. In a car, the reed switch can be attached to the glass from inside the passenger compartment, and in the case of a room, for example, somewhere behind a non-metal decorative door trim. The status indicator is a two-color LED. If it lights up green, it means the alarm is blocked and you can enter. If red, the alarm is active.

The switch is a regular switch that turns off the power. It must be secretly located inside the protected object, because after the LED lights up green, there is no more than one minute to turn off the alarm with this switch. That is, you need to first block the alarm, then enter and turn it off completely.

Switching on occurs in the reverse order, first turn on the power, the LED lights up green, and you have one minute to get out and close the door. After the sensor is triggered, the alarm starts immediately and sounds for about one minute. The circuit then returns to its original state.

The alarm output is a 12-volt electronic car siren. But, instead of it, you can connect a relay winding, the contacts of which can turn on some other signaling device.

Car security device

The diagram of the automobile version is shown in Figure 1. The contact sensors of the car are designed so that when triggered they are shorted to ground. They are connected to the circuit via diodes VD1-VD3.

When triggered, they supply a logical zero to pin 8 of D1.3. The one-shot D1.3-D1.4 starts and a logical zero appears at its output (pin 11 of D1.4) for about one minute (depending on the C3-R1 circuit). The key VT1-VT2 opens and turns on for this time.

Rice. 1. Schematic diagram of a homemade security device based on the K561LA7 microcircuit.

When the power is turned on by switch S1, charging of C1 through R2 begins. While it is charging, pin 13 of D1.4 is zero, and the output is one. The monostable is blocked.

The key VT1-VT2 is closed. In this case, the output D1.2 is one, and the HL1 LED lights up green. After C1 is charged (this takes about a minute), pin 13 of D1.4 is set to one and the monostable is unlocked. And the HL1 LED lights up red. The locking key is the reed switch SG1. If you bring a magnet close to it, it will close and discharge C1.

Security device for premises

Figure 2 shows a schematic diagram of a device for protecting the premises.

Rice. 2. Diagram of a security device for the premises on the K561LA7 microcircuit.

The difference is that here the SG2 sensor is a reed door position sensor that operates to open.

Below is a diagram of a simple and reliable alarm system on one K561LA7 chip. Two generators are assembled from four logical elements “2I-NOT”. The low frequency generator on elements DD1.1 and DD1.2 controls the audio frequency generator on elements DD1.3 and DD1.4, generating an alarm signal. A piezo emitter can be connected between pins 11 and 12 of the microcircuit, thereby simplifying the device, but in this case the signal emitted by the QZ1 piezo emitter would be weak. Therefore, an amplifier has been added to the circuit using transistors VT1 and VT2, connected via a push-pull emitter follower circuit to form a complementary pair. But even in this case, the alarm signal would not be strong enough, because For the piezo emitter to operate at full strength, a relatively high voltage is required on its plates. This result can be achieved by connecting a step-up autotransformer Tr1, mounted on a ferrite ring, to the output of the emitter follower. With this autotransformer, the voltage at the input of the piezo emitter increases 10 times and the alarm signal becomes loud enough to be heard from a great distance. The number of turns of the transformer is about 900. The number of turns of the smaller winding (pins 1 and 2) is 80 turns. After winding it, a tap is made with a double wire and the second winding (terminals 2 and 3) is wound until the remaining wire is used up. Let's consider the operation of the circuit. After power is supplied to the circuit (the supply voltage can be in the range of 6 - 15 volts), the device goes into standby mode. Pin 2 receives a logical zero through the normally closed contacts of the SA1 button, which prohibits the operation of the first generator. Accordingly, pin 4 will also have a logical zero, which will not allow the second generator to operate. The device in this mode consumes very little current within a few microamps. As soon as the contacts open, a logical one is applied to pin 2 through resistors R1, R2, which leads to the start of the first generator operating at a frequency of about 2 Hz. At the moment when a logical one appears at pin 4, arriving at pin 8, the second sound generator is turned on. The audio frequency from pin 11 is supplied to the repeater input at VT1, VT2. Next, the amplified signal through capacitor C4 is supplied to the winding (1,2) of the autotransformer Tr1. The current passing through this part of the transformer winding creates an alternating magnetic flux in the core (ring), which in turn induces an electromotive force in the entire winding, proportional to the number of turns. As a result, the piezo emitter receives an audio frequency signal with an increased voltage relative to the voltage of the power source. Depending on the tasks, the button can be replaced with a normally open one, closing it to the guard position, or replacing the button with a thin wire using the tensile tension principle.

Security alarm. Scheme

The alarm is made on a simple and affordable microcircuit CD4023(or any other...4023), in which there are three logical elements “3AND-NOT”. Despite its simplicity, the alarm has quite a good set of functions, and can compete with similar devices assembled on specialized chips or microcontrollers. In addition, the use of simple “hard” logic makes the production of alarms very simple and affordable, since no programming or searching for expensive or rare microcircuits is required.

The alarm is designed to work with five contact sensors made from limit switches. One sensor - SD5 is specialized, it is installed on the front door. The other four can be installed on windows, shutters, other doors, hatches, manholes, etc. In the closed state, the sensor contacts are open and close when the corresponding door, window, shutter, hatch, manhole, etc. is opened. That is, when it is closed, the limit switch rod is pressed, which means that its opening contacts must be connected.

The alarm operation algorithm is as follows. Switching on is carried out by the power switch. The fact of switching on is indicated by one LED. After switching on, the alarm does not respond to sensors for approximately 15 seconds. However, during the first 2-3 seconds after turning on the power, the circuit checks all sensors except the main door sensor. If any of the sensors is closed (for example, the window is not closed), then a sound signal lasts 2-3 seconds and the LED lights up, which indicates a specific sensor that is in a closed state. If several sensors are closed, several LEDs will light up accordingly.

After fixing the problem, you need to turn on the alarm power again. Further, if all sensors are normal, only the LED will light, indicating that the power is turned on. Approximately 15 seconds after turning on the power, the alarm goes into security mode. Now, if any of the sensors is closed (or several of them), the electronic siren will turn on and sound for about 15 seconds. Then, the system will return to security mode and wait for the next sensor to be triggered.

Disabling the alarm occurs in two stages. First, the code is entered using the keyboard, after which the circuit is blocked for 15 seconds, during which you can enter the room and turn off the alarm with the power switch. If you enter a room and do not turn off the power to the alarm, then after 15 seconds it will enter security mode and will go off when you open a door or window, or something else that is protected, even if you are inside the room.

To set and dial the code, a simple electromechanical circuit of switch buttons connected in series is used. Such combination locks have been described many times in this magazine, and despite such inconveniences as the need to simultaneously press code number buttons, and the inability to change the code without disassembling and resoldering, they are very effective, cheap and
simple, which is also important.

The signaling device is an electronic siren for car alarms - today it is the most affordable signaling device.

Now about the scheme. The circuit is based on a three-input RS flip-flop based on two elements of a D1 type 4023 microcircuit.
There are two types of sensors. The main door sensor is SD5, it is connected directly to pin 2 of D1.1. It is not checked by an LED and an audible signal when the power is turned on, because it is located on the main door used to exit the room, and the sensor check begins immediately after the power is turned on, that is, while the person who turned on the power is still inside the room.
The remaining SD1-SD4 sensors are equipped with LEDs for status monitoring and RC circuits that generate a 2-3 second pulse when the sensor is closed.

Through decoupling diodes VD1-VD4 they are connected to pin 1 of D1.1.
When the power is turned on by switch S10, capacitor C6 begins charging through resistor R11. With a capacitance of 10 uF and a resistance of 1 M, I got to unity in about 15 seconds, although the accuracy of the capacitor capacitance and the amount of leakage play a role here, so the result may be different. Well, during this time, while C6 is charging through R11, a low logic level voltage is present at pin 4 of D1.2. Therefore, the RS trigger D1.1-D1.2 is in a fixed position, and the output of D1.2 is a logical one, regardless of what is at the inputs of element D1.1. Therefore, during this time the trigger does not respond to sensors.

At the same time, if after turning on the power it turns out that one of the sensors SD1-SD4 is closed, then, for example, if it was SD1, the R2-C1 circuit will create a pulse lasting about 2-3 seconds, which will go through the VD1 diode to pin 11 of D1 .3, and a high logic level will appear at its output for 2-3 seconds. The transistor switch VT1-VT2 will open for 2-3 seconds and a short warning sound will sound. And the HL1 LED will light up, indicating that it is the SD1 sensor that is closed.

After charging C6, the circuit goes into security mode. Now, when any of the sensors is triggered, the RS trigger D1.1-D1.2 goes to zero at output D1.2. In this case, a high logical level is set at output D1.3, and transistors VT1-VT2 open, and the BF1 siren sounds. But this continues only as long as capacitor C5 is charged through resistor R12, that is, also about 15 seconds. Although, this time also depends on the actual capacity of capacitor C5 and the magnitude of its leakage current.

For the first stage of disabling the alarm, a keyboard of buttons S0-S9 is used (the buttons are numbered according to the inscriptions next to them on the dial pad). All switching buttons, without fixation, are connected in series, but in such a way that the code number buttons are connected with normally open contacts, and all the rest - with open contacts. And this circuit is connected in parallel with C6. The circuit is closed only if only the code number buttons are pressed at the same time. At the same time, C6 is discharged, and the circuit goes into the state in which it is after turning on the power. That is, it does not respond to the SD5 door sensor for about 15 seconds.

The installation is carried out on an industrial prototype printed circuit board.

The delay time after turning on the power can be set by selecting R11 or C6. Siren sounding time - select R12 or C5.
A cell phone can also be attached to this system for remote signal transmission (L.1).