Simple but powerful sound unit 'Emergency ...

Simple but powerful sound unit "Emergency alert". Do It Yourself.Sound simulators or electronic sound effects are widely used in various appliances and devices where warning and control sensors are applied.Sound units are especially popular in different types of the vast variety of toys, entertainment games and automatic construction kits. These are musical calls, tunes recorded in ROM with sequential alternation, simulators of animal sounds and electronic sirens often mounted on vehicles for children.You can make yourself one such device having little skills in electronics. This is a model of a powerful siren, which is powered by built-in 12V rechargeable battery or from stabilized power supply.Schematics does not require rare parts, moreover, number of details is limited to minimum. They include first of all a speaker with capacity of 3-6 W and coil resistance not less than 8 ohms, 2 Russian made transistors, one of them is quite powerful, 3 permanent resistors and two capacitors.There is a need for a button to start device working like this: you click it, sound frequency increases. Release the button, frequency lowers.It turns out to be some kind of wailing sirens... Due to small number of components in the device, the circuit can be mounted on any piece of printed or mounting board.Configuration starts working immediately, without any adjustment.For fans of electronics this can become additional pastime with a soldering iron, for a child -- powerful car signal, parents and neighbors -- extra hassle.

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Where is demo sound? Terrible quality of materiał, audio and video are unsynchronized.