https://tube.loping.net/videos/watch/5f78591d-4a7e-4095-9eb4-529a26b3576b I am showing a method of using a CdS photoresistor to control a standard triac dimmer circuit that is wired to an electric drill motor (a universal motor). The CdS photoresistor is driven by an LED that is controlled by a PWM pin on an arduino microcontroller. This system provides a very easy way to control 120V AC devices with a single PWM pin, and not use any timing code or method to detect the zero-crossing of the AC power since this is done intrinsically in the circuit. It also offers true electrical isolation between the AC line voltage and microcontroller. Sun, 12 Jul 2026 12:13:26 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://tube.loping.net https://tube.loping.net/lazy-static/avatars/8a56e488-2120-4649-a417-badf5893657b.png https://tube.loping.net/videos/watch/5f78591d-4a7e-4095-9eb4-529a26b3576b All rights reserved, unless otherwise specified in the terms specified at https://tube.loping.net/about and potential licenses granted by each content's rightholder.