From many of the surrounding insects and larger creatures we would like to stay away. But since it is not always in our power, people looking for ways to at least keep the disease at some distance from myself. In recent times, high hopes were put on different kinds of ultrasonic tweeters, including on made in... Below describes such a device. And to what extent it will be effective, everyone who made it, will be able to determine and evaluate yourself.
Schematic diagram of the ultrasonic tweeters, capable of operating in a wide frequency range as shown in Fig. 93. Here BA1 - powerful tweeter, for example, 6ГLW-4, the source of acoustic oscillations. Although the passport of the higher frequency radiation of high-frequency dynamic heads can be attributed only to a "middle" ultrasound, experience shows that they are quite efficient emitters of frequencies up to 40...50 kHz and above.
The master oscillator of the device assembled on the inverter DD1.1 and DD1.2. Other elements of this chip, form the base currents in the transistors VT1 VT4..., alternately, with a frequency of F=1/2(R2+R3)C1.connecting the emitter of BA1 to the power source. In one half cycle through the open transistors VT1 and VT4 in the other - through VT2 and VT3.
The generator transistors operate in the switching mode and especially in heat sinks don't need. Although in severe temperature conditions, they may be required. Diode VD1 - any germanium.
Desired frequency radiation (which is to be seen in the "live" experiment) set the resistor R3, It is possible to provide in advance programmirovanie on the oscilloscope scale. At these values of R2, R3 and C1 generator covers the range 16...60kHz.
The power source of the ultrasonic generator must be able to give current PTR=(u pit-2)/RL(Potr - amperes Uvolt - voltage power tweeters - in volts, RL - ohms).
Of course, for creatures of different species intolerant or frightening their frequency can be and will be most likely different. But the creation of multi-frequency "Scarecrow" with a "floating" or "hopping" frequencies, one or another of their modulation by manipulation-not a problem. The main thing - in a direct experiment to establish the parameters of ultrasound, which achieved a significant effect.
In this regard, note that in an ultrasonic "bogeys" which appeared in our markets, is almost always used piezo oscillator element with pronounced resonant properties. So the foreign apparatus, frightening (if you believe the advertising) on the frequency of some kind, say, Taiwanese mosquito on our* may not produce any impression. And, it seems, does not produce...
*) Entomologists consist of not less than 500 species of mosquitoes. Here are just some of "our": Piskun, ordinary malaria, forest malaria, bloodworm, monotony the bloodworm (well known to fishermen and their larva bloodworm), aegypti, etc.
Even more varieties in the gnats - perenosice anthrax, glanders, tularemia, plague, leprosy, etc.
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