A simple rodent deterrent. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Home, household, hobby
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The generator circuit consists of a low-frequency modulator (C1, C4, DD1.4, R1, R2), an ultrasonic oscillation generator (C3, C4, DD1.3, DD1.4, R3, R4), a power amplifier based on transistors VT1-VT3 and emitter, which is used as a high-frequency loudspeaker 4GDV-1. With the ratings indicated in the circuit, the generator emits frequency-modulated oscillations in the range of 15 ... .40 kHz. The frequency is controlled by resistor R4, the modulation frequency is controlled by resistor R2 within 2…10 Hz. If contact SB1 is set in such a way that this contact closes in case of unauthorized entry into the room, the generator can work as a burglar alarm siren, since it starts to emit modulation in frequency oscillations in the range of 1000 ... 2000 Hz.
It should be borne in mind that with prolonged work in one frequency range, rats can adapt, therefore, it is necessary to change the radiation parameters with resistors R2-R4 2-3 times a week. You can also apply this example: connect the capacitor C4 to a piece of wire that creates an additional capacitance that changes with temperature and humidity. Then the frequency will change randomly.
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Author: Bogachev Alexey, Perm; Publication: N. Bolshakov, rf.atnn.ru
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