I'd like to be able to provide my kids with the opportunity to build something a little better than a passive crystal set, but still very, very simple in terms of individual electronic parts count.
It seems to me that a CW receiver should be the easiest type to build, if I'm incorrect and an AM is easier, or just as easy, let me know.
What is the lowest parts count receiver one can build that covers some portion of the HF spectrum likely to have CW signals in it?
I'd prefer low cost parts, but low parts count is still the most important requirement. Ideally it could be breadboarded, but point to point wiring is fine. It doesn't have to be great audio quality, or even very selective and immune to noise. It just needs to be able to pick up enough of a signal that a careful listener will notice the CW in the static.
Is there a receiver design that needs 20 parts or less? 10 parts? Fewer?