Multitone Siren

Abstract



This multitone siren is useful for
burglar alarms, reverse horns,
etc. It produces five different
audio tones and is much more earcatching
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 multitone 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).
These multifrequency 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.