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 ...

This mini-series of articles describes how to build a computer’s CPU (central processing unit) out of relays. “Y” in English sounds like “guay” in Spanish (my mother tongue), a colloquial expression ...