Use low voltage so safe. I am boring old buzzer. When use AC line, danger of leakage power in the heavy rain, 3 circuits can help you!..
Today I would like to introduce the simple and economical simple siren circuits. It is suitable for beginners. My son will gradually build this circuit onto the PCB layout. Look at below! 4 Circuits.
The OFF After Delay circuit on Breadboard using MOSFET
For learn about MOSFET. I recommend Time Delay circuit easy to make and long time and a few parts than normal transistor
Here is five burglar alarm circuits for you can look as idea To protect their property from thieves. simple switching, vibration systems, touch-sensitive.
This is Simple Solar light alarm circuit with the special edition, that improve this circuit whole new to higher efficiency. use solar cell instead of LDR
The Mouse and Rat repellent circuit using astable multivibrator which use sound waves or ultrasonic so it escaped away. Use transistor and piezoelectric.
This AC 220V siren circuit is a simple siren that use 220V AC as power supply. It is small size and use a piezo speaker cause use low power and saving.