Shoo Dog !

Posted on Feb 6, 2014

We`ve all had occasion to be annoyed at inconsiderate dog owners whose animals relieve themselves on the private property of others. This problem can hardly be solved in a lasting manner using verbal (or even physical) means, so recourse to an electronic remedy is better and friendlier. The starting point for this circuit is a ready-made passive i

Shoo Dog !
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nfrared sensor (PIR), such as can be found in inexpensive movement detectors. The relay contact of the PIR energizes the power supply of the circuit shown here. The power supply generates a voltage of around 15 V after rectification by D1-D4 and filtering by R1/C3 and R2/C2. This voltage powers a square-wave oscillator comprising IC1a, R3/C1 and IC1b (acting as a buffer). The two unnecessary gates are simply connected in series with the buffer, so that they work with defined levels. The R-C network is dimensioned such that frequency of oscillation is greater than 20 kHz. The amplitude can be set using P1. An IC power amplifier follows the oscillator to amplify this tone to a level that will be deafening for dogs (and other small creatures). We use the ST Microelectronics TDA2030 ( The peripheral circuitry corresponds to the specifications in the data sheet. With a supply voltage of 15 V, the TDA2030 can generate around 5W into a 4 speaker. According to the data sheet, the supply voltage of the TDA2030 can be increased to as much as 30 V, at which level it generates a hefty 16W into 4 (or 11W into 8). However, the 4093 still must be operated at 15V, which is the maximum allowable supply voltage for a CMOS IC. In principle, any inexpensive piezoelectric tweeter whose frequency response extends past 20kHz can be used for the speaker; it should have the highest possible sound pressure level (>100dB). A suitable type is listed...

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