So are mosquitoes afraid of ultrasound? Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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So are mosquitoes afraid of ultrasound? Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Home, household, hobby

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Mosquitoes, once annoyed only by villagers and tourists, in recent years have begun to seriously disturb the townspeople. Breeding in damp basements almost all year round - fortunately, the situation for this is almost ideal - they then settle in apartments even in multi-storey buildings. Take off the usual means of struggle - various kinds of chemicals - do not help much.

Recently, various ultrasonic "tweeters" have appeared on sale, which, according to advertising, are able to keep mosquitoes at a respectful distance. But either our mosquitoes differ, say, from Singapore ones, or the frequency of the emitted signal is not the same, or something else, but to the question: “Well, how does it help?”, Those who have experienced this novelty answer somehow vaguely ...

The device described here, the schematic diagram of which is shown in Fig. 1, will allow everyone to form their own opinion on this matter. The master oscillator is assembled on inverters DD1.1 and DD1.2 CMOS K561LN2. The remaining elements of this microcircuit form the base currents of transistors VT1-VT4, alternately through transistors VT1 and VT4 or through VT2 and VT3, connecting the VA1 emitter to the power source.

Fig.1 (click to enlarge)

Powerful transistors operate in a key mode and do not particularly need special heat sinks, but they may be required in severe temperature conditions.

Diode VD1 - any germanium. Possible placement of elements on the printed circuit board is shown in fig. 2. Untinned sections of the foil under the transistors act as a kind of heat sinks. The variable resistor R3 can be of any type, for example, SDR-4 of group A.

So are mosquitoes afraid of ultrasound?
Fig. 2

Dynamic head VA1 - high-frequency power of 3-4 W with a voice coil with a resistance of at least 4 ohms, for example, 6GDV-4. Although according to the passport the highest radiation frequency of such "tweeters" is small, experience shows that they are also capable of emitting ultra-high frequency vibrations - up to 40 ... 50 kHz and higher.

The desired radiation frequency is set by a variable resistor R3. It can be equipped with a scale pre-calibrated on the oscilloscope. With the values of resistors R2, R3 and capacitor C1 indicated in the diagram, the generator covers the frequency range 16 ... 60 kHz. But this is its main frequency. Since the shape of the electrical signal of the generator is far from sinusoidal, harmonics of this fundamental tone may also appear in the acoustic spectrum (with sufficient broadband of the dynamic head), which in no way will be a drawback of the device - to frighten, so frighten ...

The power source of the device (voltage 4,5 ... 6 V) must be able to supply current

So are mosquitoes afraid of ultrasound?

Mosquitoes - annoying bloodsuckers and distributors of a number of diseases (malaria, yellow fever, etc.) - are not the only possible object of research using the device described here. Biting midges, midges (having seen over a thousand of them - carriers of anthrax, glanders, tularemia, plague, leprosy), clothes and poplar moths, cockroaches, husband, weevils, skin beetles and other living creatures, one way or another invading our lives, the layout also turn out to be sensitive to such an impact. It remains to be checked ... And perhaps, thereby starting a new direction in the work of radio amateurs. A direction in which experiments of this magnitude are only possible for a large group of people who own electronic technology

Author: Yu.Vinogradov, Moscow; Publication: N. Bolshakov, rf.atnn.ru

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