Sometimes the need arises to construct a really simple oscillator. This could hardly be simpler than the circuit shown here, which uses just three components, and offers five separate octaves, ...

It's easy to become bored spending time in airports. After all, you can do only so much work on a notebook computer with no reference material around. So, relax and have some fun at the airport–build ...

We’ve read a lot about oscillators, but crystal oscillators seem to be a bit of a mystery. Hobby-level books tend to say, build a circuit like this and then mess with it until it oscillates.