Multitone Siren

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This multi-tone siren is
useful for burglar alarms, reverse horns, etc. It produces five
different audio tones and is much more ear-catching than a single-tone
siren. The circuit is built around popular CMOS
oscillator-cum-divider IC 4060 and small audio amplifier LM386. IC 4060
is used as the mult-itone generator. A 100µH inductor is used at the
input of IC 4060. So it oscillates within the range of about 5MHz RF. IC
4060 itself divides RF signals into AF and ultrasonic ranges. Audio
signals of different frequencies are available at pins 1, 2, 3, 13 and
15 of IC 4060 (IC1).

Multitone Siren Circuit

Multitone Siren Circuit Diagram

These multi-frequency signals are mixed and fed to the audio
amplifier built around IC LM386. The output of IC2 is fed to the speaker
through capacitor C9. If you want louder sound, use power amplifier
TBA810 or TDA1010. Only five outputs of IC1 are used here as the other
five outputs (pins 4 through 7 and 14) produce ultrasonic signals, which
are not audible. Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. Regulated 6V-12V (or a battery) can be used to power the circuit.

Author: PradeeP G. – Copyright: Elektor Electronics Magazine