When a retired engineer gets too much time on his hands he has a tendency to get carried away analyzing things. When I got into club making and frequency analyzer manufacturing I couldn't help but get into the technical background of the frequency concept. At the risk of boring you to death I've written down some of the work I've done which you might find interesting. Don't worry there won't be a quiz on it, and I apologize for any typos.
To get started select a topic from the menu on the right ->