Two-tone electronic siren. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Digital technology
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On fig. 1 shows a schematic diagram of an electronic siren assembled on a single transistor and a microcircuit. Essentially, the siren consists of three generators with different timing characteristics. Transistor V1, element D1.1, capacitor C1 and resistors R1 - R3 form an oscillator with a clock frequency of about 1 Hz. The desired repetition rate of the signals can be selected by trimming resistors R2 and R3.
Ris.1
Element D1.3, resistor R4, capacitor C2 and element D1.4 constitute the second generator with a generation frequency of about 1000 Hz. And finally, element D1.3, together with resistor R5, capacitor C3 and element D1.4, form a third generator, but at a lower frequency, about 200 Hz. The siren is terminated by loudspeaker B1 connected to the output of element D1.4.
In the circuit, you can use the 155LA3 chip and any low-power silicon npn transistor, for example, KT315B.
Literature
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Elektrotehnicar (SFRY). 1976, no. 7-8
Publication: N. Bolshakov, rf.atnn.ru
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