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Dogcheyzer - horror stories for dogs - dog repeller

Dogcheyzer - "horror stories for dogs"

V.V. Bannikov, G.M. Oskva

The dogchaser is a portable electronic device that can scare off 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 dogchaser is based on the radiation of the inaudible man of ultrasound parcels, but well perceived by the dog in the form of a kind of "silent" barking. In general, the dogchaser resembles the device " Antilay ", but it is much simpler than it.

So, the simplest version of the dogchaser (Fig. 1) is assembled on just one digital chip ( DD 1) and five transistors ( VT 1 ~ VT 5). On logical elements max DD 1.1, DD 1.2, resistors R 1, R 2 and capacitors Cl , C 2 are made of an infrasound generator. It is a symmetric multivibrator, which forms rectangular pulses with a frequency of about 1.5 Hz. The second symmetric multivibrator, built on the elements DD 1.3, DD 1.4, resistor R 6, R 7 and capacitors C5, C 6 , is an ultrasonic generator, the frequency of which rectangular pulses are 20 kHz and periodically (every 0.66 s) increases about 4 times. A relatively smooth periodic "lead" ultrasonic frequency up performs the node containing the resistors R 3- R 5, the capacitor C3, the transistor VT 1 and the diodes VD 1. VD 2.

The ultrasonic oscillations of a right- angled form formed at the output pins 10 and 11 of the DD 1 microcircuit have a small 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 BF 1 piezoelectric emitter . Ultrasonic vibrations ( modulated by ultrasonic ) are excited in it after pressing the SB 1 button , which functions as a conventional power switch. The power supply circuit of the DD 1 chip is protected from accidental “ reverse polarity ” of the battery GB 1 by the diode VD 3, and the capacitors of the filter C 4 and C7 ensure the transmission of high-frequency and low-frequency oscillations along the power circuit.

If, instead of using the SP-1 piezo emitter, the ACT- 10 automotive piezo - siren is used , the range of the dogchaser is noticeably increased. A GB 1 battery can be made up of six to ten galvanic cells (316), D-0.25 batteries, or you can use a ready-made 12-volt L 1028 battery or a thin 9-volt Krona or Corundum battery . Chip K561LA7 can be replaced by K176LA7, K1561LA7 or 564LA7. Diodes VD 1- VD 3 - any silicon small-sized, transistor VT 1 - any low-power silicon 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.

When making a dogchaser, you can do without chips at all, however, then the number of transistors will increase to nine. Thus, Figure 2 shows a diagram of the second version of the device, or rather, its fragment (the rest is according to Figure 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 ultrasound transistors VT 8, VT 9, capacitors C4, C5, and resistors R 7- R 10. The ultrasonic frequency "pull" circuit contains resistors R 5, R 6, capacitor C3, transistor VT 1, and diodes VDI , VD 2 .

So that when setting up the dogchaser , which mainly consists in selecting the resistance of resistors R 3 (fig. 1) or R 5 (fig. 2), it is possible to control its work by ear, for the time being parallel to the capacitor C 4 and C5, two solders are connected by soldering with a capacity of at least 6800 pF each.