This morse code generator circuit is suitable for learning basis of communication. Unbelievably, short and long tone can be decoded into letters and text.
This is buzzer circuit easy to build with small size,cheaper using normal transistor and small piezo speaker can use for 3V to 12V as use parts resistors[...]
The mosquito repellent circuit to generates small sound frequency using transistors as bistable multivibrator. It is economical, safer than using chemicals.
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.