{"id":157166,"date":"2025-01-31T11:16:40","date_gmt":"2025-01-31T05:46:40","guid":{"rendered":"https:\/\/www.electronicsforu.com\/?p=157166"},"modified":"2025-03-07T17:18:00","modified_gmt":"2025-03-07T11:48:00","slug":"light-activated-switch","status":"publish","type":"post","link":"https:\/\/www.electronicsforu.com\/electronics-projects\/light-activated-switch","title":{"rendered":"Control Home Appliances With A Mobile Torch: DIY Light-Activated Switch Using LDR"},"content":{"rendered":"<div class=\"wp-block-image\">\n<figure class=\"alignright size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"178\" height=\"169\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2022\/06\/efy-tested.jpg\" alt=\"efy test\" class=\"wp-image-97958\"\/><\/figure><\/div>\n\n\n<p>Automation is now integral to daily life, with mobile phones serving as essential tools. This device employs a mobile phone torch to control domestic appliances, exemplifying an efficient light-operated switch. By responding to light intensity, it activates or deactivates appliances with ease.<\/p>\n\n\n\n<p>The switch detects ambient light through a <a href=\"https:\/\/www.electronicsforu.com\/technology-trends\/learn-electronics\/ldr-light-dependent-resistors-basics\">light-dependent resistor (LDR)<\/a> or photodiode. A focused beam from a mobile torch, standard torch, or laser torch triggers the system\u2014powering the appliance on with the first focus and off with the second. <\/p>\n\n\n\n<h2 class=\"wp-block-heading\">POC Video Tutorial<\/h2>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<span class=\"oWiMErZ5JSgLGsxb0\"><iframe loading=\"lazy\" title=\"Control Home Appliances with Mobile Torch | Electronics For You\" width=\"696\" height=\"392\" src=\"https:\/\/www.youtube.com\/embed\/9i1GSKcOLXo?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe><\/span>\n<\/div><\/figure>\n\n\n\n<p>The LDR sensor in the circuit translates changes in light intensity into electrical signals, driving the switching mechanism.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"402\" src=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2025\/01\/Prototype-1.jpg\" alt=\"Breadboard setup for DIY Light-Activated Switch Using LDR\" class=\"wp-image-157181\" srcset=\"https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2025\/01\/Prototype-1.jpg 700w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2025\/01\/Prototype-1-500x287.jpg 500w, https:\/\/www.electronicsforu.com\/wp-contents\/uploads\/2025\/01\/Prototype-1-696x400.jpg 696w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption class=\"wp-element-caption\">Fig 1: Author\u2019s prototype of DIY Light-Activated Switch Using LDR<\/figcaption><\/figure><\/div>\n\n\n<p>With versatile applications, this device can be handy for individuals with physical disabilities, enabling effortless appliance control. It is equally effective for managing indoor and outdoor lighting in homes. Fig. 1 shows the author\u2019s prototype on a breadboard.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Parts List<\/strong><\/td><\/tr><tr><td><strong>Semiconductors:<br><\/strong>IC1 (IC1A-IC1B) &#8211; LM358 op-amp<br>IC2 &#8211; 4017 decade counter<br>T1 &#8211; BC337 NPN transistor<br>D1 &#8211; 1N4007 rectifier diode<br>LED1 &#8211; 5mm red LED<br><strong>Resistors (all 1\/4-watt, \u00b15% carbon):<br><\/strong>R1 &#8211; 100k\u03a9<br>R2, R3 &#8211; 4.7k\u03a9<br>R4, R5 &#8211; 1k\u03a9<br><strong>Capacitor:<br><\/strong>C1 &#8211; 1\u03bcF, 25V electrolytic<br><strong>Miscellaneous:<br><\/strong>RL1 &#8211; 12V, SPDT relay<br>CON1-CON3 &#8211; 2-pin connector<br>LDR1 &#8211; Small light-dependent resistor<br>&#8211; 12V battery<br>&#8211; Mobile phone\/torch or laser light<br>&#8211; Appliance (60W 230V AC bulb)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Light-Activated Switch<\/strong> &#8211; <strong>Circuit and Working<\/strong><\/h2>\n\n\n\n<p>Fig. 2 shows the light-operated circuit diagram to switch on\/off appliances. The system is built around dual op-amp LM358 (IC1), <a href=\"https:\/\/www.electronicsforu.com\/technology-trends\/learn-electronics\/decade-counter-circuit-basics\">decade counter IC 4017<\/a> (IC2), a <a href=\"https:\/\/www.electronicsforu.com\/technology-trends\/learn-electronics\/relay-switch-pin-diagram\">12V single-pole double-throw relay<\/a> (RL1), and a few other components.<\/p>\n\n\n\n<div class=\"mepr_error\"><div class=\"locked-content\">\n<b>EFY++ CONTENT: ACCESS TO THIS CONTENT IS FREE! BUT YOU NEED TO BE A REGISTERED USER.<\/b><\/p>\n<p>Oops! This is an EFY++ article, which means it's our Premium Content. 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This device employs a mobile phone torch to control domestic appliances, exemplifying an efficient light-operated switch. By responding to light intensity, it activates or deactivates appliances with ease. The switch detects ambient light through a light-dependent resistor (LDR) or photodiode. A [&hellip;]<\/p>\n","protected":false},"author":106036,"featured_media":157181,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,23,6070,6072,3713],"tags":[1985,1911,110,12605,11882],"class_list":{"0":"post-157166","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-electronics-projects","8":"category-hardware-diy","9":"category-advanced-projects","10":"category-beginners-projects","11":"category-premium","12":"tag-diy-projects","13":"tag-do-it-yourself","14":"tag-electronics-projects","15":"tag-feb-2025","16":"tag-ldr"},"_links":{"self":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/157166","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/users\/106036"}],"replies":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/comments?post=157166"}],"version-history":[{"count":3,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/157166\/revisions"}],"predecessor-version":[{"id":159171,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/posts\/157166\/revisions\/159171"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/media\/157181"}],"wp:attachment":[{"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/media?parent=157166"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/categories?post=157166"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.electronicsforu.com\/wp-json\/wp\/v2\/tags?post=157166"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}