This musical light alarm circuit is very simple, uses only 7 components, a LDR and a 3.6 V battery or 3 x 1.2 volts rechargeable batteries. The well-known UM66 is used as the sound generator and will ...

This home smoke detector circuit warns the user against fire accidents. It relies on the smoke that is produced in the event of a fire and passes between a bulb and an LDR, the amount of light falling ...