These circuits are Simple Metronome circuit model to be simple. It use the transistor be important equipment by very the circuit is the character Astable Multi vibrator. For produce something…
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 [....]
When the temperature rise exceeds the limit, it will sound the siren rang out.
This is a Simple Refrigerator Door Alarm circuit, it will detect light of lamp in the fridge and alert with buzzer.Small size, easy to make and cheapest. [...]
Simple Refrigerator Door Alarm circuit
This is Morning sun alarm circuit using IC-4011 that hobby It will have sound alarm when morning like a normal clock alarm with lighting sensor same clock.
This is a headlights alarm circuit, when forgot turn off headlight on car. may cannot start car,batteries lose voltage. it warning buzzer using nand gate IC [...]
The 2 tone doorbell circuit, which is an electronic buzzer types,but them has melodic sound than general electric bell. People have seen two tone bell sound