If the stock is illiquid. burden burden of low-power portable radio (or a set of two stations), designed for communication in civil band 26,9 — 27,2 MHz, offer the option of their useful lives. Often, ham radio is both a car owner and cottager, who, as a person concerned for the safety of your car or suburban house. Besides there are many other areas of application of the proposed security devices on the basis of two portable radios. The main difference from other security systems is that the “alarm” signal is passed through the radio channel and range of action of the protection system depends on the power of radio transmitters and features of the passage of radio waves in the area of application of the system Even if there is only one radio station (CBS stations), is also not a problem as the receiver can use an all-band multimode transceiver type Kenwood FH-7E, Yaesu or similar (more about that below) in the circumstances, the transceiver is programmed to receive the appropriate frequency 27,175 MHz. Automatic shutdown function in the transceiver neutralized. Assessment ideas
Today is a rare vehicle not equipped with an audible alarm, however, much good in it (even expensive) less due to the almost identical set of sound signals produced when the signal “alarm” As one specialist installer car alarm buy the alarm for their “iron horse” cost less than $ 3000 does not make sense because of its uselessness in defending against car thieves, the Minutemen(“Minuteman” in translation from English. man minutes). This statement makes perfect sense.
At a mass gathering of cars in the Playground or Parking lot in the city not to allocate the signal “your car” from a stranger So the work cheap industrial anti-theft devices to cars without block “beeper” signal is now ineffective. And anti-social elements (thieves, working in this field) for a long time to learn how to convert a simple alarm before they enter the car. Purchase “fancy” alarm with pager more efficiently, but requires the owner of the car significant additional costs, and they will be justified or not — everyone decides for themselves.
According to statistics, the end of 2005 — beginning of 2006 in the Northwest region of the Russian Federation was celebrated as a boom in car thefts and break them thieves to steal. Therefore, no additional protection is not unnecessary, moreover, made their own security device and not a template that is installed secretly, is less likely to be decoded and neutralized by the offender.
The proposed “guard”, consisting of two similar radio stations and the block of the audio signal with the effect of “Serena” implemented on the chip КР1436АП1, reliable and provides the original car alarm system at a distance and beeps when opening the doors, hood or trunk of a car — all those available seats that are equipped with covert buttons that trigger when an unauthorized opening of the Hearing parallelity audio signal at the receiving unit, the owner of the car POPs up to the car or call for help, watching the situation from the window. Such a system can be equipped with any vehicle, even a truck with a system voltage 24 V (which today is in need of protection not less than others, and to establish a industrial alarm system, expensive and seemingly inefficient (inappropriate)).
The application of the proposed electronic unit allows you with small financial investments to establish effective means to monitor the safety of the car or a country house. Such a control system can also be used on large protected Parking lots and terminals, placing the receiving node in the guard room and providing each freight car transmitter.
Watchman is an all-band multimode transceiver Kenwood FH-7E.
The principle of operation of the device
As the receiving and transmitting nodes, I use the radio station “Ural-P” to the frequency 27,175 MHz Power transmission path is so portable station of 50 mW, which provides a stable range in urban areas up to 0.5 km of This distance is quite enough to, placing the car at home or parked near the housing, to control her person, while in his own apartment (cottage, house).
One radio is at home and constantly connected in the “welcome” to a stable power source with a constant voltage of 12 V. the Other is in the car. The volume of the amplifier audio frequency reception of the radio is an optional extra.
Current consumption of this radio station from a specified source in the “reception” at medium volume, is about 12 mA.
By the way, in the transmit mode, the radio of standard antenna current consumption (transmitting station) is increased to 160 mA. Each of the radio is used with the standard whip antenna, connected via standard high frequency connector SR50-74ПВ, and transmission — with passive car antenna is connected through the same connector and connected to pin automotive antenna mounted on the glass or on the roof of the cable RK-50 or similar. C-side as a transmission is better to use a car antenna mounted securely (fastened to the body or, in extreme cases, on glass or drain the car), since the antenna is fixed to the body by magnetic suction Cup, it is also easy to remove as to install. From securely of the antenna depends on the efficiency of the security device.
A schematic circuit diagram of electronic unit’s set-top box for CB radio.
Radio station “Ural-R” has no squelch, so the minor noises and noises and sometimes the radio on the given frequency at an appropriate volume to be heard. This system is not a hindrance to third-party conversations, as the power output is very small Instead of “Ural-R” it is possible to use a portable station with the same frequency and power characteristics, more importantly, to frequency of transmitter and receiver coincide, for Example, such stations domestic production can be “Pilot” (Moscow radio), “Veda-FM” (Yaroslavl radio plant) and others.
Since the “Ural-R” doesn’t signal the dial-tone, walkie-talkie working as a transmitter and installed in the car, had slightly Supplement the e-node.
Switch type П2К, by means of which the transceiver is installed modes “transmit-receive”, mechanically fixed to the radio in the car was always included on the transfer. Low-power dynamic speaker in the radio is the microphone and transmitter of sound, depending on the position of the mode switch П2К, connecting, respectively, to the input of the preamplifier, to the output of the audio amplifier.
In the left part of the diagram shows the connection of the system to the standard parts of the vehicle, the Connectors X and y it is convenient to use three – or five-pin low frequency, which in the set were used in tape recorders and radios. In the right part of the diagram shows the system connection to the station ground and the supply voltage are connected, respectively, via the terminals X3, Y3 and X1, Y1 the Contact Y2 is connected on the motherboard of the radio to the wire going from the drivers to switch modes П2К, wherein the link chain with a dynamic head must be broken, leaving the speaker is not connected.
This is done to ensure that the transmitting radio does not beep in the car when the penetration that can spook the perp or to detect the location of the transmitter.
Electronic Assembly, implemented on the chip DA1 (КР1436АП1) is a sound generator and the internal power node with Schmitt trigger At the output of the generators (output 8 DA1) are rectangular pulses with variable frequency. On hearing this sequence of pulses will be perceived as the effect of “wah-wah”, reminiscent of the sound of sirens, the pulse Frequency of the first generator set elements R2C3. For the second generator are the defining elements R3C6. Transition capacitor C4 prevents the influence of the nodes of the radio frequency generators, and does not pass the DC component of the voltage at the input of the preamplifier “Ural” on Capacitor C5 provides a more pleasant sound, softens the sound.
When power is applied to the chip (more than 10 In the terminal 1 DA1) internal trigger voltage is ready, its input — output 2 DA1. First, input low voltage level Even when a momentary input trigger with a hysteresis high-level voltage (which occurs when the vehicle door is opened and the relay K1) the trigger is being transferred to another steady state and allows both generators. They will work (and on the receiving node a “home” radio station can hear the signal “alarm”) until, until will not be disconnected power or a momentary short to ground button SA2, establishes at terminal 2 DA1 low voltage level.
Thus, thanks to the features of the chip КР1436АП1 managed to do a minimum of parts.
While experimenting with this amazing chip revealed some more features of the device, which can be useful when repeating device.
Additional node for the simultaneous control of several circuits of the limit switches.
Features of the device
So, if the capacitor C3 from the circuit to eliminate, in the output we get the single-tone signal with a frequency of about 1000 Hz (works only one generator with elements R3C6). If the underlying scheme to complement the site, shown on the next page, you will get an intermittent single-tone signal (“peak to peak”), opening with a frequency of about 2 Hz.
The VT1 transistor with its emitter-collector sauntered capacitor C6, tearing the generation of the second oscillator. For greater duty cycle (the ratio of the repetition period of pulses to their duration. — Approx. ed.) of the pulses in the latter case you should increase the resistance of the resistor R2, 750…..1000 ohms or increase the capacitance of the capacitor C3 to a few UF. All fixed resistors and capacitors can be replaced with deviations of the values of up to ±20% of the sound that it is better to use in the mode “alarm” is left to the choice of each ham In the additional node are shown relay contact K2 1. His introduction to the scheme can be interesting if, for example, to use controlled circuit in the car, and two or more (adding the same relay).
If relay K1 will control the door openings of the vehicle relay K2 in a similar manner to control the opening of the bonnet or bodywork.
Thus, the relay K2 (K1 the same type) that are connected similarly to another staff push the auto switch will connect to the base scheme an additional node, which will lead to another sound effect.
While away from the vehicle (the controlled area), the owner (guard) may, at the tone of the audio signal, to determine that it was attacked (autopsy), and to act appropriately.
Oxide capacitors C1 and C2 smooth out noise in the onboard vehicle network in the case if, for example, when the penetration from unauthorized mode is “starter”, which selects the energy from the battery.
The device is in adjustment is not needed.
Details
All fixed resistors type MLT-0,25. Electrolytic capacitors of the type K50-29 or similar non-polar capacitors — type KM5, KM-6. Relay K1-RES 15 — performance RS4.591.003 or similar, surely triggered at a voltage of 10 to 12 V.
Switch SA1 type ПД9-1, TVZ-or any small-sized latching It is necessary in order that the alarm device can be disabled when moving or car repair. ЅА2 button contacts on the circuit — type MPZ-1.
Recommendations
Before connecting the device with the elements of the radio control the audio generators, supplying power to the chip and connecting between the terminals Y2 and Y3 of the piezoelectric capsule type ZP-22. If when you first turn to the sound, once you click SA2 for setting the device to standby mode.
The elements of the device are mounted on the Board from a unilateral foil fiberglass or perforated mounting plate dimensions 20×40 mm. They are installed into the housing from the transmission station (free of batteries “the battery” compartment).
HL1 led is discharged to the outside of the lid of this compartment. It signals the opening of car doors and apply power to the transmitting node. If necessary, this item along with current limiting resistor R1 can be waived or replace HL1 on flashing led, for example, L36BSRD, TLBR5410, L816BRCS-B, L769BRG or similar — then the effect is even more colorful — luminous flux of the led will be interrupted, the Switches SA1, SA2 are set secretly.
If sets of identical radio stations no, recommended as a receiving station to use the all-band transceiver type Kenwood FH-7E, or equivalent, portable radio with scan ranges, which can be easily programmed (set up) on the frequency of the CB range.
Such a transceiver (or an all-band multimode receiver) today can easily be purchased in various companies that sells industrial equipment for radio Amateurs, and this device will serve you well not only within publishing, but also much wider, allowing radio traffic on other frequencies (including VHF), and, in the end, will lead you to becoming a licensed radio Amateur. Is it bad when a good person in our community will be more?
Especially when installing the unit in a car with a battery voltage 24 V
During node installation in the vehicle onboard voltage of 24 V is necessary slightly to modify the schema. In the gap Y1 of the conductor should be included stabilizer adapter 24 to 12 V. it may be two cascaded chips КР142ЕН8В and КР142ЕН8Б or one chip KR142EN12A (circuit adjustment of the output voltage) Current transfer mode the radio is small, so heat sinks for these chips is not needed.
Relay K1 should be replaced by any other electromagnetic relays, effectively triggered at a voltage of 24 V (it is convenient to use a regular relay for vehicles with on-Board network 24 In). The resistance of the constant resistor R1 to increase to 1 com. Oxide capacitors C1, C2 to use for a working voltage below 50 V. Chip КР1436АП1 (foreign analogue КА2410) is designed to work in circuits with a constant voltage to 29 V, therefore, in its circuit to change anything not necessary.
A. KASHKAROV, St. Petersburg
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