Personal Alarm using IC 74HC04

This circuit uses digital CMOS IC 74HC04 used power supply 3V only. The IC perform produce the frequency about 2.8kHz and 3.3kHz work can alternate into pieces warn to follow want.
These handheld piezo screamers are also known as rape alarms. They are a very loud siren. This one is particularly loud even though it runs on only two AA batteries. It uses a push-pull transformer output.
The detail is other , see in circuit picture.

Source:http://www.members.shaw.ca/novotill/PersonalAlarms/index.htm

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