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 project uses a simple LDR that is calibrated against a reference photometer in order to build a digital lux meter. This project uses a simple LDR that is calibrated against a reference photometer ...