Fridge door alarm circuit with delay time

making dark switch Photocell course, in this course you’ll explore the fundamentals of building an automatic dark-activated switch using a photocell, also known as an LDR (Light Dependent Resistor). This course covers everything from the basics of light-sensing technology to the practical applications of photocells in creating energy-efficient lighting systems. You'll learn how a photocell responds to light intensity, adjusting resistance based on available light. We’ll guide you through circuit design, where you’ll connect the LDR to a transistor and other essential components to create a switch that activates in low-light conditions, perfect for outdoor lights, night lights, and security systems. Through hands-on exercises, you’ll gain skills in assembling and testing the dark switch, adjusting sensitivity levels to control when the light activates. Additionally, we’ll discuss safety tips, circuit troubleshooting, and common issues, providing practical insights to ensure successful operation. By the end of the course, you’ll have a fully functional dark-activated switch and a solid understanding of photocell-based automation, ready for application in home or DIY electronics projects.