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Dogcheiser - dog horror story - dog repeller

Dogcheiser - “horror story for dogs”

V.V.Bannikov, city ​​of Moscow

A dog chaser ( from English , dogchaser is a dog chaser ) is a portable electronic device that can repel aggressive dogs. Such a device is useful not only for rural postmen, for whom it was originally intended, but also for any passerby, especially in the dark night time, not to mention defenseless women and weak children.

The action of the dog-chaser is based on the emission of ultrasonic transmissions inaudible by humans, but well perceived by the dog in the form of a kind of “soundless” bark. In general, the dog chaser resembles the Antilay device, but it is much simpler.

So, the simplest version of a dog - chaser (Fig. 1) is assembled on just one digital microcircuit ( DD 1) and five transistors ( VT 1 ~ VT 5). On the logic elements DD 1.1, DD 1.2, resistors R 1, R 2 and capacitors Cl , C 2 made infrasound generator. It is a symmetrical multivibrator, forming rectangular pulses with a frequency of about 1.5 Hz. The second symmetric multivibrator, built on the elements DD 1.3, DD 1.4, resistors R 6, R 7 and capacitors C5, C 6 , is an ultrasonic generator, the frequency of which is 20 kHz square-wave pulses and increases periodically (every 0.66 s) about 4 times. A relatively smooth periodic "pull-up" of the ultrasonic frequency upwards is performed by a unit containing resistors R 3 -R 5, capacitor C3, transistor VT 1 and diodes VD 1. VD 2.

The ultrasonic vibrations of a rectangular shape formed at the output terminals 10 and 11 of the DD 1 microcircuit have little power. Therefore, they are amplified by the power of a push-pull bridge amplifier assembled on transistors VT 2- VT 5. The emitter load of this amplifier is a piezoceramic emitter BF 1. Ultrasonic vibrations ( modulated by infra-sound ) are excited in it after pressing the SB 1 button , which performs the function of a conventional power switch. The power supply circuit of the DD 1 chip is protected against accidental " reverse polarity " of the GB 1 battery by the VD 3 diode , and the filter capacitors C 4 and C7 provide the transmission of high-frequency and low-frequency oscillations, respectively.

If instead of using a SP-1 piezoelectric transducer , an ACT- 10 automobile piezoelectric siren is used , the range of the dog - dozer will significantly increase. The GB 1 battery can be composed of six to ten galvanic cells (316), D-0.25 batteries, or use the finished 12-volt L 1028 battery or, but the worst, a 9-volt “Krona” or “Corundum”. The K561LA7 chip can be replaced with a K176LA7, K1561LA7 or 564LA7. Diodes VD 1- VD 3 - any silicon small-sized, transistor VT 1 - any silicon low-power with a base current gain of at least 30. Transistors VT 2, VT 4 and VT 3, VT 5 are interchangeable with any of the KT3102 and KT3107 series, respectively.

In the manufacture of a dog-chaser, you can do without chips at all, however, then the number of transistors will increase to nine. So, Fig. 2 shows a diagram of the second variant of the device, or rather, its fragment (the rest is shown in Fig. 1), in which the infrasound generator is assembled on transistors VT 6, VT 7, capacitors C 1 , C2 and resistors R 1- R 4 and ultrasonic - but transistors VT 8, VT 9, capacitors C4, C5 and resistors R 7- R 10. The circuit of the "removal" of the ultrasonic frequency contains resistors R 5, R 6, capacitor C3, transistor VT 1 and diodes VDI , VD 2 .

So that when setting up a dog-chaser , which mainly consists in selecting the resistance of resistors R 3 (Fig. 1) or R 5 (Fig. 2), you can control its operation by ear, for the time being, in parallel with a capacitor C 4 and C5, two capacitors are connected by soldering with a capacity of at least 6800 pF each.