To do this, water sprayers installed at the ends of the dropper pipes are fixed on top of the room fan grille (it is advisable to use a floor fan with a high rod). Once an hour (or in another algorithm “programmed” by a radio amateur for specific tasks), the water pump and tank will spray moisture in small drops onto the rotating fan blades. In this case (considering that the fan rotates in one horizontal plane, but has a free rotation angle of up to 90°), humidification of a large area of the room is achieved.
Thanks to the use of aquarium sprayers, moisture is sprayed in small drops, so water leakage (and puddles under the fan) does not occur. The device was practically tested by the author in the hot summer of 2007.
Attention!
The electronic timer described above can be replaced with an industrial version similar in purpose (and vice versa), described in detail in subchapter 4.2. In this case, there is no need to assemble the electronic device yourself, but, for example, take a ready-made the electronic unit.
1.2. Lightning indicator
Distant thunderstorms interfere with radio communications and navigation, and those passing nearby can damage communication equipment with lightning-induced signals.
Direct lightning strikes are especially dangerous, leading to the destruction of equipment, fires and human casualties.
Lightning discharges induce powerful pulse signals on power and communication lines, and even short surges in voltage in them can cause malfunctions and failure of expensive equipment. electronic devices, computers. The likelihood of thunderstorm danger is especially high in rural areas with long open lines, with high antenna masts for receiving and transmitting equipment, which local radio amateurs try to install higher (on a hill), on poles or metal masts.
It is advisable to turn off radio equipment when a thunderstorm approaches.
A nearby thunderstorm can be seen and heard, but how can you get advance warning? After all, everyone needs this: tourists and fishermen, yachtsmen and radio amateurs who spend many hours on the air. Early warning of thunderstorm danger is also very important for other people working or relaxing far from shelters.
1.2.1. Methods for measuring lightning activity in numbers
There are two known methods for recording thunderstorm activity. Both of them were invented and researched at the end of the 19th – beginning of the 20th centuries.
Static - recording occurs as the electric field strength in the atmosphere increases from 100 V/m (in normal conditions) to 1-40 kV/m before a thunderstorm (lightning discharges also occur in clear skies). This method is widely known to many in physics courses.
A device that can record field strength is called an electrometer.
Modern electrometers do not require complex antennas; they register the electric field of the atmosphere, even if the control device is installed on a windowsill, and the electric field of a pre-electrified comb made of a mixture of plastics is recorded at a distance of 1–2 m (a pre-electrified (rubbed) ebonite stick will be “seen” from afar) .
The second method is electromagnetic, in which the field strength is determined by the spectral composition and intensity of radio wave pulses with a frequency of 7-100 kHz, emitted by lightning (discharges).
It is not without reason that one of the signs of an approaching thunderstorm is an increased level of rustling sounds (crackles) perceived by the human ear when listening to signals from radio stations in various ranges of long and medium waves.
It is believed that this method was invented by A. S. Popov.
Based on this principle, a lightning indicator device was created, the electrical circuit of which is shown in Fig. 1.5.
Rice. 1.5. Electrical diagram lightning indicator
1.2.2. How the device works
Extension coil L1, the upper (according to the diagram) output of which is connected to the WA1 antenna – a 45–60 cm pin, increases the efficiency of the device’s input circuit L2C1. Input circuit tuned to 330 kHz (above maximum spectral density pulses of radio waves emitted by lightning electrical discharges).
The setting of the device’s input circuit also determines the distance from which an approaching thunderstorm can be “detected.” With the elements indicated in the diagram, the device will detect an approaching thunderstorm from a distance of 130–150 km (an experiment with the finished device was carried out in the village of Erakhtur, Ryazan region, Shilovsky district in the summer of 2007).
The signal amplified by transistor VT1 is supplied to the recording stage (VT2-VT4). A high-frequency (HF) pulse (amplified by VT1) with a voltage amplitude of 1–3 V causes transistors VT2 and VT3 to open and the oxide capacitor C4 to discharge. The charging current of capacitor C4 passes through the high-frequency diode VD1 and resistor R5, which leads to a delay in the closing of transistor VT4 and the lighting of the indicator LED HL1.
1.2.3. About details
Coils L1 and L2 are chokes of type DPM-1, DPM2, DM, D179–0.01 with the corresponding inductance values indicated on the electrical diagram.
Instead of the HL1 LED, you can use another indicator LED (with a current of up to 12 mA so that the device does not lose efficiency) or a sound indicator (for example, KPI-4332–12 with a built-in generator audio frequency). The sound indicator instead of the HL1 LED is turned on according to the poles indicated on its body.
Resistor R4 sets the response threshold (sensitivity) of the device.
Device supply voltage 3–6 V direct current. 2–3 are suitable as a power source AA batteries(batteries) type AAA or AA or a stabilized adapter must be with transformer isolation from a 220 V network.
Since the device operates at relatively low frequencies, there are no special requirements for its elements.
Transistors VT1-VT4 can be any low-power silicon and have the appropriate structure. Instead of VT1, VT3, VT4, you can use KT3102 with any letter index, 2N4401 or similar in electrical characteristics.
Transistor VT2 - p - p-p conductivity, for example, KT3107 with any letter index or 2N4403.
Diode VD1 - any pulse (germanium or silicon), for example, D9, D18, KD503.
1.2.4. Setting up
The device does not require adjustment (except for setting the response threshold with variable resistor R4).
How to check?
A correct device assembled from serviceable parts is easy to check. Bring the finished device with the connected batteries 1.5–2 m to a gas stove with automatic ignition. Briefly press the auto-ignition button on the stove. The indicator LED should respond with short flashes. If there is no stove with auto-ignition, the device can be checked differently, using a lighter with a piezoelectric element. The LED should flash briefly when the piezoelectric element of the lighter is “turned on” at a distance of 0.5–1 m.
1.2.5. Practical Applications
In addition to long-range detection of an approaching thunderstorm front, the device also works well at close distances. Thus, you can check the performance of gas stoves with automatic ignition, piezoelectric lighters (for gas stoves - there are such separate devices in the form of a huge match), and also find sources of poor contact in electrical communications - both indoors and “outdoors”. A bad electrical contact, for example in electrical wiring (which is a source of electromagnetic interference to radio communication devices), can be detected from a distance of several meters using a lightning indicator, even if the source of the bad contact is deep in the wall.
1.2.6. Industrial devices for similar purposes
I have been able to see portable lightning indicators (with LCD) on more than one occasion for free sale. As a rule, these devices display the speed of approach of a thunderstorm, the time until its arrival, the expected intensity and other parameters. Alarm system – sound and light. Radio wave pulses are received by a magnetic antenna; analysis of their intensity, frequency and spectral composition allows a “smart” electronic device to conclude that a thunderstorm is approaching.
1.3. Linear indicator scale
Most of the described voltage comparator circuits, in which LED bars serve as indicators, are built on the principle of parallel comparison of input voltage (hence the need for a large number of comparing devices - comparators). The number of comparing devices corresponds to the number of channels (LEDs) in the line.
The one shown in Fig. does not have this drawback. 1.6 circuit, with a sequential comparison of the input voltage, in which there is only one comparator that compares the constant voltage signal at the input with a cyclically changing reference voltage.
Rice. 1.6. Electrical diagram of the indicator scale device
The comparison results are transmitted to shift register on the D2 chip, from the output of which they are read onto the indicator line using a parallel code. This circuit design allows for greater accuracy, clarity and dynamic readings. Along with other positive distinctive qualities of this device over other similar ones - ease of manufacture, inexpensive parts, non-criticality of the supply voltage - it is able to compete for its popularity among radio amateurs and professionals. An alternating voltage and pulses can be supplied to the input of the circuit (with a little modification) - then it can become a universal, accurate indicator with a light scale that is not inferior in the dynamics of changes in indications and accuracy to pointer instruments with class 2. In the line of LEDs, the discreteness of indications should be taken into account when need to calibrate the light scale.
1.3.1. How the device works
The scheme works as follows. The clock generator on the popular CMOS chip K561LA7 produces rectangular pulses. Maximum clock frequency register at a supply voltage of 5 V - 2 MHz, U p = 12 V, f max = 5 MHz. They arrive at the clock input C of the successive approximation register D2, performing a clock-by-clock shift of the information loaded into the register. In parallel with this, the process of measuring the level of incoming voltage takes place using comparator D3. The result of the comparison (high or low logic level) from the output of the comparator goes to the data input D of the register, thereby determining the state of its outputs. At the end of the input conversion cycle analog signal into a series of logical pulses, an active logical “zero” signal appears at the output of the CC register (pin 3), which acts on the input of logic D4.1. Elements D4.1, D1.3 generate a stopping pulse. Therefore, the arrival of pulses to the clock input C register is not perceived and the LED scale of the indicator registers the achieved input signal level. The locking low level is taken from the conversion output Q1 (the second least significant digit), since an LED line of ten LEDs is used. If you use three lines of four LEDs in series or a line of 12 LEDs, they are connected in series to the outputs Q11 - Q0 of the register. Then logic elements D1.3, D4.1 are excluded, and pin 3 (CC) is connected to pin 14 (St) of the register, and from this the successive approximation register operates continuously, cyclically.
The number of indicated signal levels can be increased by adding microcircuits - registers and bar indicators. Such devices are widely used in industrial automation for visual indication of dynamic processes. I use the circuit in a car as an engine speed indicator (tachometer).
1.3.2. Practical Applications
An LED scale can be installed in a car, on the instrument panel, to indicate the on-board power supply voltage, fuel level in the tank, engine temperature, environment, and so on. The scope of application of this scheme can be as wide as desired.
1.3.3. About details
The ALS361A LED line can be replaced with ALS361B, ALS362P, KIPT03A-10Zh (yellow light), - 10L (green light), or made up of two lines like ALS345A (8 indicators) or ALS317B (5 indicators). Or, instead of an LED line, install ten LEDs of the AL307BM type or similar in series.
1.4. Anti-theft devices
Anti-theft systems, according to many experts, are the most reliable among all types of security systems used in practice in large and small retail outlets. The devices actually have a high probability of detecting an anti-theft tag (due to the exceptionally high power of the pulses supplied to the antennas). However, even with full compliance with acoustomagnetic technology (EAR) in the production of devices, these impulses have a negative effect on humans (with frequent and prolonged exposure) - mainly due to power. The little-studied features of acoustomagnetic systems are discussed below.
1.4.1. Amazing features of anti-theft systems
Anti-theft systems can be seen in almost every retail outlet today. Externally, they look like two open gate leaves installed in parallel. Between these flat “gates” a person leaves the store (sales area).
In Fig. 1.7 shows a photo of the anti-theft system.
Rice. 1.7. Appearance anti-theft system
If the buyer does not carry goods “marked” with special microtags, the “gate” lets him through without complaint. If the tag on the product is not removed (neutralized), the alarm system will go off and notify the sales area with loud alarm sounds.
Then the guards will come running, and the unlucky “carrier” will be caught.
Acoustomagnetic technology was developed by Sensormatic. Later, seeing the success of this technology, the Tyco concern acquired this company. It is now a division (and brand) of ADT (American Dynamics Technology). The active devices themselves (antennas, electronics units) are no longer subject to copyright (patents have expired). Therefore, another manufacturer appeared - the WG company.
1.4.2. How the device works
Anti-theft gates have a transmitting and receiving antenna operating at a frequency of 58 kHz with possible deviations of ±200 Hz. During operation, the antenna emits pulses with an amplitude of 40 V and a duration of 1.5–1.7 ms (filled with a frequency of 58 kHz). The pulse repetition period is 650–750 ms.
A high field strength is created around the antenna, which causes the amorphous metal to resonate at the irradiation frequency.
Attention!
This magnetostrictive effect is very dangerous for pacemaker owners.
During the pause (650–750 ms), the same antenna works for reception. The power of the tag's initiated radiation decreases exponentially over time according to a complex law that manufacturers keep secret. Therefore, it is quite difficult to imitate the response signal. But the presence of even a few or even the slightest signals like these greatly impairs the operation of the system. It is known from practice that if 50-100 m from the store (sales hall) in which the acoustomagnetic system is located, there is another similar system, then they create mutual interference that is difficult to eliminate. In advertising, manufacturers claim that their equipment is effective and safe (how could it be otherwise?), but it seems to me that with its help (not intentionally) they conduct experiments to study the influence of powerful (albeit short-term) impulses on human health.
To understand what an amorphous metal is, in this case, you should consider in detail the marks themselves, which sellers place in product packaging.
In Fig. 1.8 shows an acoustomagnetic mark.
Rice. 1.8 Acoustomagnetic tag of the anti-theft system
Each of us has seen and even held these strips in our hands many times. Let's try to figure out how they work.
♦ If you tear off the anti-theft tag from the product packaging and examine it from reverse side, behind the translucent plastic you can see a metal strip.
♦ If you cut the tag, you can remove 3 metal strips: two from amorphous metal (they are more shiny) and one from ordinary ferromagnetic tape.
In Fig. Figure 1.9 shows the internal structure of acoustomagnetic tags.
Rice. 1.9. Internal structure of acoustomagnetic tags
1.4.3. About harm to human health. Practical tips to live a little longer
Acoustomagnetic electronic devices among all anti-theft systems are the most harmful to human health. The ultrasonic frequencies that their antennas emit are comparable in frequency to some biologically active frequencies. The peak radiation power can be measured in kilowatts.
Draw your own conclusions.
In any case, when passing through the “security gate”, try not to linger (so as not to receive a dose of radiation), and in particular, if the alarm system is triggered (an alarm is heard), try to get out of the zone of direct influence of the antennas, and only then deal with the cause "triggering" of the alarm.
Unfortunately, you can often see the opposite picture. For example, an alarm is triggered when an elderly woman passes through the “gate” of the EAR system. The buyer, having heard the alarm, wondering about the reasons for such attention to her by electronics, stops at the “gate” and waits for the guards to approach her. All this time she is under high-power radiation, the effect of which on the human body has not been fundamentally studied.
The same recommendations apply to another aspect: try to go through these gates as little as possible, even when the guards require you to do so in view of the search for an active tag located somewhere on the product you just bought. A better solution may be to show them all the items purchased and carry them through the gate individually.
1.4.4. Methods to combat EAR
Is it possible to suppress an industrial EAR system?
Of course you can. In particular, by introducing interference from other sources into the system.
Today, many readers have access to the Internet, where you can easily (if desired) find the electrical circuit diagram of the EAR anti-theft system suppressor. That is, make sure that the alarm does not turn on when passing through the “gate” with a purchase from which (for various reasons) the acoustomagnetic tags have not been removed (neutralized).
I do not discuss the legal issue of removing unpaid purchases from the store (which is why I am not providing a diagram of the EAR suppressor). Something else is important. Even if you deprive the anti-theft alarm system of its “voice,” this will not reduce the harmful effects of electronics on the human body - the buyer, when he leaves the store (sales floor).
1.4.5. How to detect radiation
For the radio amateur who wants to independently understand the problem and find it The best decision, I propose to independently detect the radiation of the anti-theft systems described above.
To do this, you need to take a special sensitive device with you to the store, for example, a signaling device - an indicator of high-frequency radiation from the Master Kit NS178.
1.5. A simple buzzer controlled by logic zero
Activating the buzzer by connecting a power source to the device is not always acceptable, especially if the buzzer needs to be controlled by another electronic device, which forms the control pulse of logical zero. In this case, power is supplied to the sound alarm constantly. This decision is justified by the fact that the shaper device sound signal assembled on one K561 series chip (using CMOS technology), and the current consumption does not exceed 10 mA.
In Fig. 1.10 shows the electrical circuit of the sound alarm.
Rice. 1.10. Electrical circuit of the sound alarm
At the input of the device, you can install a button with contacts to close. According to the diagram (Fig. 1.10), the logical zero signal is connected to pin 1 of the DD1 microcircuit and the common wire.
The button simulates the supply of a logical zero signal to pin 1 of the DD1.1 microcircuit.
The circuit consists of an infra-low frequency generator using elements DD1.1, DD1.2 (pulses with a frequency of 0.5 Hz at pin 4 of the microcircuit) and a pulse generator with a frequency of 1 kHz using elements DD1.3, DD1.4.
When there is a low logic level signal at pin 1 of the DD1.1 element (when the security loop is broken), the generators begin to work, and the first generator controls the operation of the second, therefore, at the output of the node (pin 11 of the DD1.4 microcircuit), bursts of pulses appear with a variable frequency.
The output signal from pin 11 of the DD1.4 microcircuit can be fed to the input of another circuit or to an amplification transistor stage, loaded, in turn, to a piezoelectric capsule or (if a higher power amplifier is used) to a dynamic head.
Practical application of the device is universal. The sound alarm can be used in security devices, toys, radio communications (for example, as sound generator“transmission” signal and tone call) and in various other cases.
This electronic unit does not require adjustment.
The power source is stabilized with an output voltage of 5-15 V.
1.6. Simple radio pager
A pager is a device that transmits a signal (including an alarm signal) over a distance. In this case, the prefix “radio” means transmitting a signal via radio waves. Many modern alarm systems are equipped with a radio pager device, which includes a key fob - detector - radio signal receiver. In particular, cars are equipped with such alarms.
Today you can buy almost everything. Those who have a day tend to do so. Those who want to do it with their own hands are creative. For the creative types of radio amateurs, I propose on the pages of the magazine a simple electrical circuit of a radio pager - a device that transmits an “alarm” radio signal over a distance of up to 0.5 km in line of sight. A car owner who has such a device is completely free (particularly at night) from jumping out of a warm bed at the “call of an alarm system that sounds similar to mine.” Those who have repeated the recommended device do not need to disassemble “their own or someone else’s car starts singing”, having heard, as a rule, a standard car alarm signal through the thickness of the double-glazed windows. The autopager will signal right at home, without disturbing the neighbors with sharp trills.
Let's consider the electrical circuit of the pager shown in Fig. 1.11.
Rice. 1.11. Electrical circuit of a radio pager
The pager transmitter consists of an oscillator and an amplifier high frequency. The generator is made on transistor VT1, the amplifier is made on transistor VT2.
Pager transmitter stabilized quartz resonator, operating at the third harmonic of quartz 48 MHz (144 MHz).
Circuit C4, L1 is tuned to the second harmonic of quartz, circuit C5, L2 – to the third harmonic.
Coil L1 contains 8 turns of PEL-1 wire with a diameter of 0.3 mm, coil L2 contains 4 turns of the same wire. In this case, the diameter of both coils is 4 mm.
An installation copper stranded wire (with insulation) 30 cm long is used as the WA1 antenna. MGTF-1.0 wire is well suited for these purposes.
A signal can also be supplied to point A (see Fig. 1.11) from external sources (alarm sensors and others). It is important here that the signal at point A consists of pulses of sound frequency received by a person by ear (100-1800 kHz). This “alarm” signal will be broadcast when the appropriate situation arises. About the options practical application described below.
Limiting resistor R4, ripple-smoothing capacitor C1 and zener diode VD1 are the voltage stabilizer of the car generator during engine operation. If it is known that the device will operate from a battery or a stabilized power source, these elements can be excluded from the circuit.
The SB1 “ON” locking button turns the radio pager into standby mode. The device will begin to emit a radio signal when the contacts of the SB2 button, which is a standard lighting limit switch (activated when the doors are opened), are closed.
1.6.1. Setting up
The adjustment is carried out with the RF amplifier turned off (the connection point between the collector of transistor VT1 and the transition capacitor C6 is temporarily broken).
By forcibly closing the contacts of the SB1 button, supply power and check the generation at the collector of transistor VT1. If the elements are in working order and the connections are correct, the device does not need to be adjusted.
DIY thunderstorm recorder
This device is perfect for those who are engaged in tourism, hiking, and more. It allows register a thunderstorm within a radius of approximately 80 km, which will allow you to find shelter, hide, and turn off electrical equipment in time.
Assembling a thunderstorm recorder is not so difficult, since it does not contain scarce parts and special settings; you just need to configure R4 - this is the sensitivity threshold of the detector.
Extension coil L1 boosts its effectiveness. The input circuit L2 C2 is tuned to about 330 kHz.
L2-dangles on any circuit from an old radio, frame diameter 5mm, 360 turns of wire 0.2mm, winding height 10mm. Circuit L1 has the same parameters, only 58 turns of 0.2mm wire. In my version, this coil is not there, I replaced it with another - you can experiment with it.
Printed circuit board V LAY format.
About the details of a homemade thunderstorm approach recorder. Transistors VT1-VT4 can be any, from KT315/KT361 to KT3102/KT3107. Diode VD1 - any pulse.
Operating principle: the signal amplified by transistor VT1 is supplied to the recording stage (VT2-VT4). The RF pulse opens transistors VT2 and VT3 and discharges capacitor C4. Its charging current, passing through the diode VD1 and resistor R6, leads to a longer opening of the transistor VT4 and the lighting of the indicator light VL1.
You can use an LED or a sound indicator with a built-in generator - whichever is more convenient for you. You can check the recorder using a piezo lighter - clicking the lighter at a distance of half a meter from the antenna. It is recommended to ground the device, this will increase sensitivity.
This simple design allows changes in atmospheric charge to be monitored. For example, by recording an increase in atmospheric discharge, the approach of a thunderstorm front can be predicted. The magnitude of the atmospheric charge on a sunny day is about 100 mV, but when thunderclouds accumulate and before rain, the magnitude electric charge increases many times.
In the event of a thunderstorm, the voltage can increase to several thousand volts shortly before the lightning strikes. This describes the circuit of an atmospheric electricity monitor, the change of which is displayed on an LED scale.
Description of the operation of the atmospheric electricity detector
The input circuit consists of an antenna, the signal from which is fed to operational amplifier DA1 (TL071) used as a comparator. This type The operational amplifier has a JFET input and a gain of up to 100 dB. Its non-inverting input is connected to a voltage divider formed from resistors R3 and R4, and the non-inverting input is connected to the antenna.
Resistor R2 protects DA1 from excessively dangerous input voltage, while resistor R1 keeps the non-inverting input stable. Since the operational amplifier TL071 has a very high gain, resistor R5 is added to the circuit to form feedback with appropriate restrictions.
Depending on the input voltage, output 6 DA1 will have a voltage in the range from 2.5 to 5 V, which is supplied to input 5 of the LM3914 (DD1) microcircuit through variable resistor R6. Resistor R7 limits the maximum sensitivity.
Microcircuit - integrated circuit, which is capable of measuring (linearly) input voltage and display the values on a line of LEDs. In essence, it turns out to be a classic analogue LED display. The current flowing through the LEDs is limited by the LM3914 itself, eliminating the need for external resistors. In this circuit, the input voltage from 1.7 to 4.2 V is distributed over five LEDs.
Device setup
Before turning on for the first time, turn the knob of the variable resistor R3 completely counterclockwise, and the variable resistor R6 to approximately the middle of the range. Apply power and turn the slider of resistor R6 to test the device. Usually the LED VD2 and even VD1 light up for a short time, this indicates the correct operation of the equipment and a change in the atmospheric charge.
The final adjustments should be made on a sunny day with a clear sky, turning R4 until only VD5 glows, which indicates normal atmospheric electricity. The scheme, despite its simplicity, works very well and allows you to warn of the approach of a thunderstorm long before it starts.
An insulated wire about 3 meters long can be used as an antenna, and the common wire of the circuit can be grounded, for example, connected to a central heating battery.
Attention! To avoid being struck by lightning during a thunderstorm, you must disconnect the antenna from the device.
A device such as a thunderstorm recorder is a good thing for hikers and more. It registers thunderstorms within a radius of approximately 80 km. This will allow you to disconnect the Internet cable in time, since network cards they often burn during close lightning strikes, or you have time to go take off your drying clothes outside before the rain gets them wet. Assembling a thunderstorm recorder is not so difficult, since it does not contain scarce parts and special settings; you just need to configure R4 - this is the sensitivity threshold of the detector.The extension coil L1 increases its efficiency. The input circuit L2 C2 is tuned to a frequency of about 330 kHz, L2 is wound on any circuit from an old radio, frame diameter 5mm, 360 turns of wire 0.2mm, winding height 10mm. Circuit L1 has the same parameters, only 58 turns of 0.2mm wire. In my version, this coil is not there, I replaced it with another - you can experiment with it. in LAY format.
About the details of a homemade thunderstorm approach recorder. Transistors VT1-VT4 can be any, from KT315/KT361 to KT3102/KT3107. Diode VD1 - any pulse. Operating principle: the signal amplified by transistor VT1 is supplied to the recording stage (VT2-VT4). The RF pulse opens transistors VT2 and VT3 and discharges capacitor C4. Its charging current, passing through the diode VD1 and resistor R6, leads to a longer opening of the transistor VT4 and the lighting of the indicator light VL1.
You can use an LED or a sound indicator with a built-in generator - whichever is more convenient for you. You can check the recorder using a piezo lighter - clicking the lighter at a distance of half a meter from the antenna. It is recommended to ground the device, this will increase sensitivity. Author: (please specify).
This device is perfect for those who engage in tourism, hiking, and more. It allows register a thunderstorm within a radius of approximately 80 km, which will allow you to find shelter, hide, and turn off electrical equipment in time.
Assembling a thunderstorm recorder is not so difficult, since it does not contain scarce parts and special settings; you just need to configure R4 - this is the sensitivity threshold of the detector.
Extension coil L1 boosts its effectiveness. The input circuit L2 C2 is tuned to about 330 kHz.
L2-dangles on any circuit from an old radio, frame diameter 5mm, 360 turns of wire 0.2mm, winding height 10mm. Circuit L1 has the same parameters, only 58 turns of 0.2mm wire. In my version, this coil is not there, I replaced it with another - you can experiment with it.
Printed circuit board in LAY format.
About the details of a homemade thunderstorm approach recorder. Transistors VT1-VT4 can be any, from KT315/KT361 to KT3102/KT3107. Diode VD1 - any pulse. Operating principle: the signal amplified by transistor VT1 is supplied to the recording stage (VT2-VT4). The RF pulse opens transistors VT2 and VT3 and discharges capacitor C4. Its charging current, passing through the diode VD1 and resistor R6, leads to a longer opening of the transistor VT4 and the lighting of the indicator light VL1.
You can use an LED or a sound indicator with a built-in generator - whichever is more convenient for you. You can check the recorder using a piezo lighter - clicking the lighter at a distance of half a meter from the antenna.
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