This is Simple 555 Alarm sound circuit, for beginner as buzzer sound. IC1 is pulse generator, to transistor PNP for boost current to speakers.
Often drivers forgot to turn off lights when parking. They cannot start the machine, ran out battery. This Headlight Warning buzzer circuit can help.
This is simple music keyboard circuit. The origin frequency sound circuit model astable multi vibrator. if press switch S1 the circuit will begin the work. [...]
This is simple Warble tone generator circuit , use scr as main of oscillator and signal will be boost, then feedback to SCR again. Output is 32 ohms speaker [....]