Here the simple schematic of multitone siren alarm circuit. This multitone siren is effective for reverse horns, burlgar alarms, and many others. It generates five various audio tones and is much more earcatching than a single-tone siren.
The circuit is constructed around well known CMOS IC 4060 as oscillator-cum-divider and small audio amplifier chip LM386. IC 4060 is utilized as being the main part of multitone generator. A 100uH inductor is utilized at the input of IC 4060. So it oscillates within the assortment of about 5MHz RF. IC 4060 itself separates RF signals into AF and ultrasonic ranges. The audio signals of different frequencies are obtainable at pins 1, 2, 3, 13 and 15 of IC 4060 (IC1). These multifrequency signals are mixed and fed to the audio amplifier assembled close to IC LM386.
The output of IC2 is fed to the speaker via capacitor C9. If you need louder sound, use power amplifier circuit using TBA810 or TDA1010.
Only five outputs of IC1 are put to use right here since the other five outputs (pins 4 through 7 and 14) generate ultrasonic signals, that are not audible.
You may assemble the circuit on a general purpose Printed CIrcuit Board (PCB) and enclose in a appropriate cabinet. Regulated 6V-12V (or possibly a battery) could be utilized to supply the circuit to be work.
PDF version: Multitone siren alarm circuit