Here are some DIY LDR switch circuits available on our website and the web. LDR switches are used to switch a relay or other device when light are present or absent. LDRs or Light Dependent Resistors ...

Setting the threshold at which the circuit switches the output is adjusted by a variable trimpot acting as a voltage divider with the LDR.

The low-powered device consists of a PIC micro-controller, an LDR (light dependent resistor) for light sensing and a low current relay which switches between the two modes.

Witnessing its success, over 2,000 LDR devices have been set up in 600 gram panchayats of Hanamkonda, Warangal, Mahabubabad, Jogulamba Gadwal and Sangareddy districts.