The trickier part was getting the original bells to work — in North America, it takes up to 90 VAC to get a phone’s ringer going, which is quite a bit more than the lowly Arduino can handle.

With a 555 on the BOM, you never know what you’re going to get. With 40 of the versatile timer chips in a build, you might just get something completely unexpected, like this 555-based eight-… ...