| You can use a germanium diode or even Shottky now instead of a “crystal”. Such a simple radio can be a gateway drug to a very complex and deep hobby. In my case it went like that: 1. Built a simple radio 2. Could hardly hear anything, need to add an amplifier to it
3. Now it’s better but captures a lot of noise 4. Design a filter to select just that one station 5. Now I want to listen to more stations. 6. Ugh, you can’t design a good filter with variable frequency. Enter the superheterodyne world. 7. Now finally got something that resembles a tunable AM radio, but it kinda whistles / hums a lot. Ah, so the mirror image is a real thing?! 8. Need a higher IF to be able to better reject the image before the mixer. Ok, let’s make a double conversion superhet then. 9. Buy a set of ceramic filters and play with them to get the best selectivity. 10. Try to add more amplification only to learn if you go too far you get an oscillator instead of an amplifier. 11. The sound level is not stable. Add AGC. 12. Pick up some stations from 5000+ km away. Nice. But there is some weird distortion. Oh, I’ve been a culprit of frequency selective fading… Fast forward and now I’m building a PLL synchronized AM product demodulator with a squaring loop for carrier recovery. Fun. Lot of fun! Wholeheartedly recommend! |
As someone who's always dabbled in electronics, skimmed and read some books, my primary complaint abot most electronics texts is that they just talk about individual topics: oscillators, amplifiers, etc.
What they never talk about, is putting them all together.
But as witnessed by this list, that's what a radio is. A collection of these "meta" components into a whole to get a better radio experience.
A radio built like this, with individual subsystems connected together, is much more understandable. Many (not all) radio schematics are presented as a whole, rather than the parts, or why you might (or might not) want to change one part or another (not components, but one, say, filter circuit to a different one).
It just seems to me that once you get past some basic theory, starting with a radio, and then systematically taking it apart is a better way of approaching electronics education.