One of the most practical uses of the Internet of Things is to turn your lights on and off. Many of you probably remember similar functionality in the form of The Clapper, which let families of the distant past flip their lights with a loud clap. Both The Clapper and IoT switches operate with the use of relays, but that doesn’t mean there aren’t other ways to tackle the problem — like this build from Robin Hartley that physically flips a light switch.
Most IoT switching devices that handle a lot of electricity use relays for good reason: they’re safe, they’re reliable, and they’re cheap. A mechanical relay works by using a small voltage to energize an electromagnet, which pulls closed a switch for a high-voltage circuit, such as a lamp connected to mains power. Hartley’s design does the same thing, but in a fun, over-engineered way by using servos to toggle a standard wall-mounted light switch.
The servos are controlled with an Arduino Pro Micro, and a LM393 sound sensor lets the user toggle the light by snapping or clapping. Those, along with a battery and the complementary components, are mounted on a 3D printed frame. When the frame is placed over a light switch, a nearby person and switch the lights just by making a loud noise. Sure, a relay is probably more practical, but this is a fun build that could work well for renters who aren’t allowed to modify their light switches.