Building a crystal clock source for a CPU used to be a bit of an effort but these days, there’s nothing to it. Even if your CPU or other device needs an external clock, you just slap in an inverter, a crystal, and two capacitors together, and you are done, right? Maybe not. [Dave Collins] got interested in the common circuit and pulled out his scope and an array of different kinds of inverters. He looked at inverters and NAND gates and a few common circuit configurations.
This is one of those things you just assume is of little importance, but it turns out your choice of circuit architecture and active device can have a big impact on the output. But who has time to do all the testing? Thanks to [Dave] you don’t have to.
Honestly, we are as likely to just buy a “can” oscillator if we need something like that these days. But still, it is interesting to see what kind of differences there are between using different inverting elements.
Crystal oscillators are relatively ancient tech, but they still beat everything until you get into exotic and expensive things. If you want to look even deeper into what goes into these, [Ken] can help.