There is such a science - harmology. No matter how much people invent anything useful, sooner or later it will still be used for harm.
Ultrasound has long been used in some types of washing machines, locators, alarms, and in industry. But the main purpose of this device is to cause damage. Many have heard about methods of struggleultrasound with moles, mice, mosquitoes. And now we will doULTRASONIC GUNS for attacking humans. While studying audio engineering - setting up speaker systems, I discovered an interesting effect: when a signal is appliedon the high-frequency speaker, and gradually increasing its frequency, there comes a moment when the sound (whistle) is no longer perceived by the ear, but the head begins to hurt noticeably. In other words, the subtlest whistle can no longer be heard (neither the source nor the presence), but the effect is very unpleasant. Even after turning off the ultrasonic gun, unpleasant sensations persist for some time.The ultrasonic gun circuit does not contain expensive parts and can be assembled in an evening.
Attention! The transistors are drawn incorrectly in the diagram - here's how to connect them:
The basis of the device is a digital microcircuit - 6 logical inverters CD4049 or HEF4049. To replace it with the Soviet K561LN2, you will need to slightly change the connection pinout. As a powerful sound emitterultrasonic gunwe take a high-frequency speaker from a speaker, for example 5GDV-6, 10GDV-4, 10GDV-6 or any other from old Soviet speakers, the more powerful.The entire structure fits into a metal case from a lamp, is powered by any source of 5-10 V, with a return current of 1 A. For example, 4 AA batteries or one 6-volt lead-acid battery.
As you can see, ultrasonic gunIt turns out to be very compact and autonomous. It can be used for the speedy departure of unnecessary guests (who suddenly have a headache), sabotage during classes in the classroom, dispersing a group of drunken jackals under the windows, “scaring away” the bosses from your workplace... In general, this ULTRASONIC GUNNER, in my opinion, is a must-have will find application. Especially now, with the onset of summer, the problem becomes urgent ghouls - mosquitoes. Having caught a couple of pieces and placed them in a jar (why a couple? So that it wouldn’t be boring), slowly changing the generation frequency, we irradiate them with ultrasound. When they start to wobble, remember the frequency and put it on the windowultrasonic gun likea barrier from these vampires. Another scheme
An ultrasonic emitter is a generator of powerful ultrasonic waves. As we know, a person cannot hear ultrasonic frequency, but the body feels it. In other words, the ultrasonic frequency is perceived by the human ear, but a certain part of the brain responsible for hearing cannot decipher these sound waves. Those who are involved in building audio systems should know that high frequencies are very unpleasant for our hearing, but if we raise the frequency to an even higher level (ultrasonic range), the sound will disappear, but in fact it is there. The brain will try to decode the sound unsuccessfully, resulting in headache, nausea, vomiting, dizziness, etc.
Ultrasonic frequency has long been used in a variety of fields of science and technology. Using ultrasound, you can weld metal, do laundry, and much more. Ultrasound is actively used to repel rodents in agricultural machinery, since the body of many animals is adapted to communicate with their own kind in the ultrasonic range. There is also data about repelling insects using ultrasound generators; many companies produce such electronic repellents. We suggest you assemble such a device yourself, according to the diagram below:
Let's consider the design of a fairly simple high-power ultrasonic gun. The D4049 chip works as an ultrasonic frequency signal generator; it has 6 logic inverters.
The microcircuit can be replaced with a domestic analogue K561LN2. The 22k regulator is needed to adjust the frequency; it can be reduced to the audible range if the 100k resistor is replaced with 22k, and the 1.5nF capacitor is replaced with 2.2-3.3nF. Signals from the microcircuit are supplied to the output stage, which is built on only 4 medium-power bipolar transistors. The choice of transistors is not critical, the main thing is to select the complementary pairs that are as close as possible in terms of parameters.
Literally any HF heads with a power of 5 watts or more can be used as a radiator. From the domestic interior, you can use heads like 5GDV-6, 10GDV-4, 10GDV-6. Such HF heads can be found in acoustic systems manufactured in the USSR.
The ultrasonic gun is assembled with your own hands using only two logical inverters and has a minimum number of components. Despite the ease of assembly, the design is quite powerful and can be used against drunken drunks, dogs or teenagers who sit and sing in other people's hallways.
Ultrasonic gun diagram
Microcircuits CD4049 (HEF4049), CD4069, or domestic microcircuits K561LN2, K176PU1, K176PU3, K561PU4 or any other standard logic microcircuits with 6 or 4 logical inverters are suitable for the generator, but you will have to change the pinout.
Our ultrasonic gun circuit is based on the HEF4049 chip. As already mentioned, we need to use only two logical inverters, and it’s up to you to decide which of the six inverters to use.
The signal from the output of the last logic is amplified by transistors. To drive the last (power) transistor, in my case, two low-power KT315 transistors were used, but the choice is huge, You can install any NPN transistors of low and medium power.
The choice of power switch is also not critical; you can install transistors from the KT815, KT817, KT819, KT805, KT829 series - the latter is composite and will work without an additional amplifier on low-power transistors. In order to increase the output power, you can use powerful composite transistors like KT827 - but to boost it, you will still need an additional amplifier.
As a radiator, you can use any midrange and high-frequency heads with a power of 3-20 Watts, you can also use piezo emitters from sirens (as in my case).
By selecting the capacitor and the resistance of the trimming resistor, the frequency is adjusted.
This self-assembled ultrasonic gun is quite suitable for protecting a dacha area or a private home. But we must not forget - the ultrasonic range is dangerous! We cannot hear it, but the body feels it. The fact is that the ears receive the signal, but the brain is not able to decode it, hence the reaction of our body.
Collect, test, rejoice - but be extremely careful, and I say goodbye to you, but not for long - AKA KASYAN.
A submersible ultrasonic transducer is a device designed to transmit ultrasonic vibrations into a liquid medium, containing a sealed housing with a diaphragm, which is part of the surface of this housing, inside which piezoelectric emitters and electrodes are located and fixed to the diaphragm, which are electrically connected to a high-frequency cable that serves to supply piezoelectric emitters of high-frequency electrical voltage from an ultrasonic frequency generator.
It is used to excite ultrasonic cavitation in a liquid cleaning medium, which intensifies the processes of cleaning parts from contaminants. Used in ultrasonic cleaning baths with a volume of over 50 liters.
Fig.1 Submersible transducer
in U.Z. bath
The structure of the ultrasonic submersible transducer is shown schematically in Fig. 1.
The generator is connected to a 220 volt 50 Hz network and converts the voltage frequency to 25,000 Hz (25 kHz) or 35 kHz. depending on the design of the submersible converter.
High-frequency voltage is supplied through a cable into a sealed housing of the converter, made of stainless steel, inside which piezoelectric emitters are mounted, connected in parallel.
Fig.2 Design of a piezoelectric emitter
The piezoelectric emitter is the main component of the submersible ultrasonic transducer. The structure of this emitter is shown in Fig. 2.
The emitter has two piezoelectric plates (piezoelements) located between two metal plates: a steel one located on the back side and an aluminum one on the front side.
The piezoelements are pulled together into one piece with the linings by means of a central bolt. A high-frequency voltage is applied to the central electrode located between the piezoelements.
The piezoelectric emitter converts electrical energy into high-frequency mechanical vibrations, which are transmitted to the diaphragm of the submersible transducer, from which these vibrations are transmitted to the washing liquid.
The number of piezoelectric emitters in a submersible ultrasonic transducer can range from 4 to 11 or more.
Piezoelectric emitters are fixed to the diaphragm using an adhesive connection.
Fig.3 Submersible transducer
A general view of the ultrasonic submersible transducer with a partially cut out back cover is shown in Fig. 3. It can be seen that the piezoelectric emitters are arranged in several rows, two in each row.
Submersible ultrasonic transducers can be used both in ultrasonic cleaning baths specially designed for them, and in cleaning baths already available to the customer. The convenience of these converters is that they can be easily installed in various parts of the bath volume.
Unlike ultrasonic transducers, which are firmly attached to the cleaning bath at the bottom or side, submersible transducers can be replaced within minutes.
The generator for powering submersible transducers with high-frequency voltage can be located from the ultrasonic bath at a distance of up to 6 meters.
Immersion transducers can be placed in cleaning baths in three different ways:
Fig.4 Placement of the transducer in the ultrasonic bath
The first two methods do not require making holes in the wall of the bathtub.
Some types of mounting of a submersible transducer in an ultrasonic cleaning bath are shown in Fig. 4.
When placing the converter at the bottom of the bath, it is necessary to take into account the height of the layer of washing solution above the converter diaphragm.
You should strive to ensure that the height of this layer is a multiple of half the wavelength of ultrasonic vibrations transmitted into the washing solution by the submersible transducer.
In this case, due to the reflection of ultrasonic vibration waves from the water-air interface, a zone of standing waves is created in the cleaning solution (reverberation phenomenon). When ultrasonic waves reverberate in a liquid, the efficiency of ultrasonic cleaning is slightly higher.
As an example, we will determine the optimal height of this layer for a specific submersible transducer.
It is known that the speed of sound in water is 1485 m/sec. The wavelength of ultrasonic vibrations is equal to the speed of sound divided by the frequency of these vibrations.
Let's assume that we have a submersible ultrasonic emitter whose diaphragm oscillation frequency is 25,000 Hz (25 kHz). The wavelength in this case will be 0.0594 m. Half the wavelength is 0.0297 m or 2.97 cm. The optimal height of the liquid in this case above the surface of the submersible transducer should be 2.97 cm x n where n is any positive integer.
Fig.5 Standing waves in an ultrasonic bath
For example, for n=40, the optimal height of the level of the washing solution above the surface of the submersible converter will be 2.97x40=118.8 cm. The above is illustrated in Fig. 5.
Placing submersible ultrasonic transducers on the walls of the cleaning bath is recommended when its depth is more than two times less than its width or length. In this case, the converters can be placed either on one wall of the bath or on its opposite walls.
The video shows the placement of submersible transducers on the side walls of the bath and the operation of submersible ultrasonic transducers located on the bottom of the bath.
Submersible transducers in action
When ultrasonic vibrations propagate in a liquid, a phenomenon called cavitation occurs, which means the formation of cavitation cavities in the liquid in the rarefaction phase of the sound wave and its subsequent collapse in the compression phase.
Fig.6 Effect of frequency on ultrasound cavitation
The behavior of cavitation cavities when changing the oscillation frequency is shown in the graph in Fig. 6.
The y-axis on the left side shows the amount of energy released during the collapse of a single cavitation cavity (cavitation energy), and the y-axis on the right shows the number of cavitation cavities per unit volume of liquid.
As can be seen from the graph, with an increase in the frequency of ultrasonic vibrations, the number of cavitation cavities in the liquid increases, and the cavitation energy decreases.
As the frequency of ultrasonic vibrations decreases, the number of cavitation cavities in the liquid decreases, and the cavitation energy increases.
Moreover, for each frequency of ultrasonic vibrations, the product of the energy released by the cavitation cavity when it collapses by the number of these bubbles in the liquid is a constant value approximately equal to the energy transmitted into the liquid by the ultrasonic submersible transducer.
The influence of the frequency of ultrasonic vibrations on the number of cavitation cavities is discussed in detail on the website
For practice, it is important that the number of cavitation cavities be as large as possible, but at the same time the cavitation energy must be sufficient to remove contaminants. Thus, to clean parts from contaminants loosely bound to the surface (fats, oils), converters with a frequency of 35-40 kHz should be used, and to clean parts from contaminants firmly bound to the surface (polishing pastes, varnish and polymer films), submersible converters with a frequency of 35-40 kHz should be used. lower frequency 20-25 kHz.
change the picture
Fig. 7 Ultrasonic bath with converters of different frequencies
The most optimal solution is to create conditions when the number of cavitation cavities would be large and at the same time the cavitation energy would also be large.
These conditions are implemented in an ultrasonic cleaning bath with submersible transducers located on its walls, as shown in Fig. 7. Another option for the location of submersible transducers can be seen if you move the cursor to this figure.
In this case, two converters are used with different oscillation frequencies of 25 and 35 kHz. A converter with a frequency of 35 kHz ensures the creation of more cavitation cavities in the volume of washing liquid, and a converter with a frequency of 25 kHz increases the cavitation energy of these cavities.
When determining the number of required submersible transducers, one must proceed from the fact that the maximum efficiency of ultrasonic cleaning is achieved with an ultrasonic power of 10...30 watts per 1 liter of bath volume.
For example, for a bathtub with a volume of 50 liters, two converters of the PP25.8 model are sufficient (see table below).
For large-volume ultrasonic cleaning baths, for example, over 250 liters, satisfactory results are achieved with an ultrasonic power of 4.5 watts per 1 liter of bath volume. For example, for a bath with a volume of 1000 l, 11 converters of the PP25.8 model are sufficient
Currently, there are many designs of ultrasonic submersible transducers on the domestic market.
The table shows the technical characteristics of submersible ultrasonic transducers from TNC Technosonic LLC (Moscow).
This article does not fully address all aspects of the design and use of submersible ultrasonic transducers. However, the presented material may be useful for specialists who are faced with specific tasks for the first time in choosing the optimal option for an ultrasonic bath for cleaning products.
Ultrasound is elastic acoustic waves, inaudible to humans, whose frequency exceeds 20 kHz. It is customary to distinguish between low-frequency (20...100 kHz), mid-frequency (0.1...10 MHz) and high-frequency (more than 10 MHz) ultrasonic vibrations. Despite kilo megahertz, ultrasonic waves should not be confused with radio waves and radio frequencies. These are completely different things!
By its physical nature, ultrasound is no different from ordinary audible sound. The frequency boundary between sound and ultrasonic waves is arbitrary; it is determined by the subjective properties of human hearing. For reference, high-frequency vibrations are well felt by animals (including domestic ones), and for bats and dolphins they are vital.
Ultrasound, due to its short wavelength, travels well in liquids and solids. For example, ultrasonic waves in water are attenuated approximately 1000 times less than in air. This leads to the main areas of their application: sonar, non-destructive testing of products, “sound vision”, molecular and quantum acoustics.
To generate ultrasonic vibrations, the following types of emitters (ultrasonic transducer) are used:
Piezoceramic (piezo);
Electrostatic;
Electromagnetic.
For the latter option, even ordinary high-frequency audio loudspeakers (in slang “tweeters”) are suitable, which have sufficient efficiency to generate signals in the near ultrasonic range of 20...40 kHz.
Piezoceramic ultrasonic emitters (Table 2.10) are produced, as a rule, in pairs with frequency-matched piezo receivers. Typical parameters of an “ultrasonic tandem”: resonance frequency 37...45 kHz, sound pressure level at a distance of 30 cm - 95...105 dB(A), operating voltage 12...60 V, capacitance 1000...3000 pF, transmitter output impedance 200...500 Ohm , receiver input impedance 10…30 kOhm.
Table 2.10. Parameters of ultrasonic emitters
It is recommended to apply not unipolar, but multipolar pulses to the plates of ultrasonic piezo emitters, i.e. during pauses, generate a voltage of reverse polarity. This contributes to accelerated discharge of the equivalent emitter capacity and increased performance.
In Fig. 2.53, a...l shows diagrams for connecting ultrasonic emitters to MK. To generate multipolar pulses, transistor bridges and isolation transformers are widely used. If you reduce the generation frequency, then the given circuits will fit “one to one” for the audible range, i.e. for the previously discussed piezoceramic sound emitters.
Rice. 2.53. Diagrams for connecting ultrasonic emitters to MK (beginning):
a) smoothing the signal shape supplied to the ultrasonic emitter BQ1 using inductor L1. Resistor R1 regulates the amplitude;
b) transistors VT1, VT2 alternately open with short pulses from MK. For reliability, you should choose transistors with a large permissible collector current so that they do not fail with low ohmic resistance of the inductor L1\
c) capacitor C1 differentiates the signal and eliminates the DC component, which allows you to connect the ultrasonic piezo emitter BQ1 to a bipolar power source;
d) low-power ultrasonic transceiver. The divider R1, R2 determines the operating point of the ADC MK when receiving a signal and the amplitude of the output pulses when transmitting a signal;
e) ultrasonic rangefinder transceiver. Pulse frequency 36...465 kHz, voltage at the emitter BQ1 50...100 V (the maximum is selected by capacitor C3). Diodes VD1, VD2 limit the signal to the receiver. Transformer 77 contains 15 turns of PEV-0.3 wire in windings I and II, and 100...200 turns of PEV-0.08 in winding III (ring M2000HM K10x6x5); ABOUT
About Fig. 2.53. Diagrams for connecting ultrasonic emitters to MK (continued):
f) the use of the DD1 logic chip eliminates the simultaneous opening of transistors of one arm in hardware. Pulse noise that occurs in the power circuit due to non-simultaneous switching of inverters DD1.l...DD13 and the spread of the current-voltage characteristics of transistors is eliminated by the filter L /, C1. Diodes VD1... VD4 are installed in case of replacing the audio HF speaker BA1 (10GD-35, 6GD-13, 6GDV-4) with a more powerful ultrasonic piezo emitter;
g) increasing the power of the BQ1 emitter using a voltage doubler on the DD1 chip and increased power supply +9...+ 12 V. Transistor VT1 matches the logical levels;
h) an increase in the voltage amplitude at the BQJ emitter occurs due to the increased supply voltage +9 V and the accumulation of energy in the inductor L1\
i) field-effect transistors K77, VT2 (replacement for IRF7831) reduce energy losses during switching. Resistors R1, R2 prevent the transistors from opening when MK is restarted; ABOUT
About Fig. 2.53. Diagrams for connecting ultrasonic emitters to MK (end):
j) the ultrasonic echolocator operates at a frequency of 40 kHz and generates pulses with a duration of 0.4 ms. The signal amplitude on the BQ1 piezo emitter (Murata) reaches 160 V. The inductance of the secondary winding of transformer T1, together with the capacitance of the BQ1 piezo emitter, forms an oscillatory circuit tuned to a frequency close to 40 kHz. The inductance of the primary winding of transformer T1 is 7.1 MK H, the secondary winding is 146 MK H, quality factor Q > 80;
k) ultrasonic hydroionizer operates at a frequency of 1.8…2 MHz. Transformer T1 is wound on three 50BH K20x 10x5 cores. Windings I and II each contain 4 turns of PEV-0.3 wire folded in three, winding III contains 12 turns of PEV-0.3 wire. Coil L1 contains 5 turns of PEV-0.8 wire on a mandrel with a diameter of 8 mm with a pitch of 1 mm. The BQ1 emitter has a diameter of 30 mm (PZT piezoceramics). Resistor R1 reduces voltage surges at the drain of VT1.
