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
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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...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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