The ultrasonic emitter is a generator of powerful ultrasonic waves. As we know, a person does not hear the 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 engaged in the construction of audio systems should know that the high frequency is very unpleasant for our hearing, but if we raise the frequency to an even higher level (ultrasonic range), then the sound will disappear, but in fact it is. The brain will try unsuccessfully to decode the sound, resulting in headache, nausea, vomiting, dizziness, etc.

Ultrasonic frequency has long been used in various fields of science and technology. With the help of ultrasound, metal can be welded, washed and much more. Ultrasound is actively used to scare away rodents in agricultural technology, since the body of many animals is adapted to communicate with their own kind in the ultrasound range. There is also evidence of repelling insects using ultrasound generators; many companies produce such electronic repellents. And we suggest that you independently assemble such a device, according to the following diagram:

Consider the design of a fairly simple high-power ultrasonic gun. The D4049 microcircuit operates 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. The signals from the microcircuit are fed 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 choose the complementary pairs that are as close in parameters as possible.

As a radiator, you can use literally any HF heads with a power of 5 watts or more. Heads of type 5GDV-6, 10GDV-4, 10GDV-6 can be used from the domestic interior. Such HF heads can be found in acoustic systems made in the USSR.

It remains only to arrange everything in the case. For the directionality of the ultrasound signal, a metal reflector must be used.

A few days ago I received another order. The buyer wanted to order a powerful ultrasonic cannon to combat drunken youth, for whom the day begins at night when all normal people are asleep. Without thinking twice, I chose a proven scheme of a powerful ultrasonic emitter. The gun itself is built on just one standard logic chip.

Literally any similar microcircuit containing 6 logic inverters will do. In our case, a CD4049 (HEF4049) microcircuit is used, which can be successfully replaced with a domestic one - K561LN2, only you need to pay attention to the pinout, since K561LN2 differs from the one used by some conclusions.

Since the circuit is quite simple, it can be implemented on a breadboard or in a hinged manner. The amplifier is assembled on complementary pairs of KT816 / 817, due to the use of these keys, the power of our gun is 10-12 watts.

As an emitter, it is desirable to use high-frequency heads of the 10 GDV type or import; it is not advisable to use a piezo emitter.

The case - from a Chinese electronic transformer 10-50 watts, had to be redone, since the board did not fit.

The 1.5nF capacitor is responsible for the frequency (which was then replaced by 3.9nF, since with the capacitor indicated in the circuit, the lower frequency limit is exactly 20kHz, and with such a replacement, the frequency can be adjusted within 10-30kHz) and a variable resistor (as a result, the setting do by rotating this resistor).

Base resistors can be replaced with 2.2kΩ, which are more common than those shown in the diagram. This emitter is powered by a stabilized 5 Volt power supply with a current of 1 A (supply voltage range 3.7-9 Volts).

Medical Faculty

Course 1

1 semester

1 stream

Lecture number 5

"Ultrasound"

Compiled by: Babenko N.I.

2010 r.

Ultrasound and its receipt. Ultrasound emitters.

Ultrasound is mechanical vibrations with a frequency of more than 20,000 Hz, which propagate in elastic media in the form of longitudinal waves. Sources of ultrasound are:

1. Natural:

2. Artificial:

acoustic-mechanical transducers;

electroacoustic transducers (piezoelectric, magnetostrictive).

Natural sources of ultrasound are sources not created by human hands and independently existing in nature.

Live springs: grasshoppers, crickets, fish, bats, dolphins. Inanimate sources: wind, landslides in the mountains, earthquakes.

Artificial sources of ultrasound are called acoustic transducers because they convert mechanical or electrical energy into the energy of ultrasonic vibrations.

Acoustic-mechanical transducers are transducers in which ultrasonic vibrations occur when the flow of a liquid or gas is interrupted. Examples: Galton whistle, ultrasonic siren.

Electroacoustic transducers are transducers in which ultrasonic vibrations occur when some substances are acted upon by alternating electric or magnetic fields.

Piezoelectric transducers (piezo - pressure) are transducers that use the phenomenon of the inverse piezoelectric effect to obtain ultrasound.

The piezo effect can be direct and inverse.

The direct piezoelectric effect consists in the appearance of charges on the surface of some crystals (piezodielectrics) under the action of mechanical stress (compression, tension, bending). Fig. 1.

With direct piezoelectric effect:

the amount of charge on the surface is proportional to the applied mechanical stress;

the sign of the charge is determined by the direction of the mechanical action.

no impact compression tension

The inverse piezoelectric effect is the phenomenon of a change in the size (deformation) of a dielectric when it is placed in an alternating electric field.

Substances with pronounced piezoelectric properties are called piezoelectrics or piezodielectrics: Rochelle salt, barium titanate, quartz.

Magnetostrictive transducers are transducers that use the phenomenon of magnetostriction to generate ultrasound. Magnetostriction is the phenomenon of a change in the shape (size) of some ferromagnetic substances under the influence of an alternating magnetic field.

These substances include:

Nickel and its alloys;

Cobalt and its alloys;

Ferrites are ceramic compounds based on oxides of iron, nickel, zinc.

A substance in the form of a rod is placed inside the coil. When the coil is connected to a source of alternating electric voltage of ultrasonic frequency, the electric current acts on the rod with its magnetic component and causes its deformation (elongation) with the current frequency. Fig. 2

MODERNIZED ULTRASONIC GUN "IGLA-M"

Have a ltrasound are elastic waves of high frequency. Usually, the ultrasonic range is considered to be the frequency range from 20,000 to several billion hertz. Now ultrasound is widely used in various physical and technological methods. The fact that ultrasound actively affects biological objects (for example, kills bacteria) has been known for over 70 years. Electronic equipment with a scanning ultrasound beam is used in neurosurgery to inactivate certain areas of the brain with a powerful focused high-frequency beam. High-frequency vibrations cause internal tissue heating.

Until now, there are discussions about the physical effect of ultrasonic vibrations on the cell and even about the possible disruption of DNA structures. Moreover, there is evidence that at the micro level - not at the level of the structure of the body, but at some more subtle level, ultrasonic exposure is harmful.

Ultrasound can be obtained from mechanical, electromagnetic and thermal sources. Mechanical emitters are usually all sorts of intermittent sirens. In the air, they emit vibrations with a power of up to several kilowatts at frequencies up to 40 kHz. Ultrasonic waves in liquids and solids are usually excited by electro-acoustic, magnetostrictive, and piezoelectric transducers.

The industry has long been making devices forultrasonic effects on animals, for example:

Appointment

A miniature dog repeller is a wearable electronic device (assembled in a mini-flashlight housing) that emits ultrasonic vibrations that are audible to dogs and not perceived by humans.

Operating principle

The device is designed to protect against attacks from dogs: ultrasonic radiation of a certain power usually stops an aggressively tuned dog at a distance of 3 to 5 meters or causes it to flee. The greatest effect is achieved when exposed to aggressive stray dogs.

Specifications

• Supply voltage (1 battery type 6F22 (KRONA)), V 9
• Consumption current, no more, A 0.15
• Weight with batteries, no more, g 90

As you can imagine, this is a weak toy, but we will make the device much more powerful! Continuing the experiments with ultrasound (), a number of interesting improvements and improvements were made. This is how a revolutionary method of influence (naturally negative) was produced on a living organism of two ultrasonicemitters with a difference frequency of several hertz. That is, the frequency of one emitter, for example, 20,000 Hz, and the other, 20010 Hz. As a result, onultrasonic radiation superimposed infrazvukovoe, which greatly enhances the destructive effect!

The circuit is standard, a generator on CD4069 + an amplifier on three N-P-N transistors. Power supply not less than 12 V, at current up to 1 A.

To enhance the directional effect, we use cylindrical sound resonators. Their role will be played by an ordinary nickel-plated tube from a vacuum cleaner.Just do not spoil the vacuum cleaner, the tube is sold separately at the bazaar or in the spare parts store.

We cut two pieces to an experimentally determined length (about a couple of centimeters), and attach them to HF heads like 5GDV-4 or any others. You can buy a double nozzle for a car exhaust pipe, the installation is much more convenient, and the effect will be even better.

We insert the high-frequency speakers inside, in the back we mount the board with the battery.

Returning from work at night or wandering through dark alleys, there is a danger of being attacked by stray dogs, whose bites are sometimes life-threatening, if you do not see a doctor in time. It is for these cases that smart human brains have come up with an ultrasonic repeller.

Industrial repellents have a rather complex scheme and are made on rather scarce components.

In this article we will consider a variant of such a repeller using the famous 555 timer series. The timer, as you know, can work as a generator of rectangular pulses, it is this connection that is used in the circuit.

The generator operates at a frequency of 20-22 kHz, as many animals are known to "communicate" in the ultrasonic range. Experiments have shown that frequencies of 20-25 kHz cause artificial fear in dogs, thanks to the tuning regulator, the generator can be tuned to a frequency of 17-27 kHz.

The circuit itself contains only 6 components and will not cause any difficulties. It is advisable to use a multi-turn regulator for more accurate tuning to the desired frequency.
The piezo emitter can be taken from a calculator or any other musical toys, you can also use any HF heads with a power of up to 5 watts, there is simply no point anymore.

The device works effectively at a distance of 3-5 meters, since there is no additional power amplifier in the circuit.

As a power source, it is convenient to use a crown, or any other source with a voltage of 6 to 12 volts.

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