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 ...

[Gord Payne] has one with an elegant sensor solution, it detects finger movement using a light ... the LDR from the LED decreases as the pipe is bent, and with a simple divider circuit a voltage ...

You’re asking what is LDR ... the market light up whenever there is an input power. These don’t take into account whether there is a real need for the light or not. Here is an intelligent PC desk lamp ...