'Beeper' Using 1C 555

Here is a 'beeper' circuit employing two 555 ICs. It can be used in various circuits (having supply voltage of 5 to-15V DC) that require an alarm or a 'beeping' signal.

BEEPER Using 1C 555
when used with TTL ICs
Vcc = +5V

Voltage at Pin 4 (IC1) State of Beeper
Vcc (logic 1) Beeping
0V (logic 0) Off
when used with CMOS ICs
Vcc = 5V to 15V (same as CMOS supply)

Voltage at Pin 4 (IC1) State of Beeper
Vcc (logic 1) Beeping
0V (logic 0) Off
IC1 is connected in astable mode in the circuit in such a way that squarewave output at about 1 Hz is obtained. lC2is also connected in astable mode, but it gives an output with about 1 kHz frequency.
The output of IC1 (pin 3) is connected to 'Reset' terminal (pin 4) of IC2. So, the continuous I kHz tone of IC2 is interrupted by the I Hz signal from IC1, producing a'beep-ing' sound. Capacitor C4 is used to restrict DC signals.
The circuit operates satisfactorily when it is to be activated by a relay or a mechanical switch, but when it is to be operated by logic ICs, such as CMOS or TTL ICs, a bit of modification is required. Instead of connecting pin 4 of ICI to Vcc, it should be connected to the output of the logic element through which it is to be activated. A logic'I'at pin4 will activate the beeper and logic '0' will turn it off. Rest of the circuit would remain the same.

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