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