I was listening to story of QualComm in Acquired podcast. This is highly related.
Radios, how do they work? (2024)
51–60 of 72 posts
Re: Radios, how do they work? (2024)
#52Re: Radios, how do they work? (2024)
#53To get an idea about radios, I made a crystal radio when I was in 7th grade, I only had few components. The only component I had difficulty in getting was the crystal oscillator (I was living in a rural town). It was mind blowing when I first heard the audio through IEMs ! It felt magical that this contraption was working without any battery source.
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 ca…
> You can use a germanium diode or even Shottky now instead of a “crystal”.
Or a razor blade or a piece of roofing lead and a needle.
Re: Radios, how do they work? (2024)
#54Earlier quoted context omitted.
Are you objecting to the trivial extension to cos(α - β)? The cos(α + β) identity itself is nicely explained in the text. The third thing you quote is the result of fairly simply symbol manipulation that requires no new knowledge apart from the original cosine identity and the obvious corollary about subtracting an angle being the same as adding a negated one. There is zero advanced math there. No complex numbers, no…
To be fair, I think most people regard “not advanced math” to exclude trig, and maybe algebra too. Fear and loathing of math is a thing.
skill issue
Re: Radios, how do they work? (2024)
#55To get an idea about radios, I made a crystal radio when I was in 7th grade, I only had few components. The only component I had difficulty in getting was the crystal oscillator (I was living in a rural town). It was mind blowing when I first heard the audio through IEMs ! It felt magical that this contraption was working without any battery source.
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 ca…
There's something to note here.
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.
Re: Radios, how do they work? (2024)
#56Earlier quoted context omitted.
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 ca…
I have used a synchronous AM detector once in a radio, its a game changer for listening to shortwave.
Oh, thanks, good to know. Now I feel more motivated. Because actually it’s not as easy as it looks from the text books. It’s like with drawing an owl. Yeah, pass the signal through a mixer and feed recovered carrier to its LO port and you’re done. Sure. Simple. Now just recover the carrier. So far I have built a PLL that locks to a clean signal but stops locking when the signal is modulated too much. Aargh.
Re: Radios, how do they work? (2024)
#57My grandfather, when he was a boy in the 1910s or 1920s built a radio out of a round oatmeal box, copper wire, and a crystal. I never saw the original, but he built a replica of it (featured in a book in the 1970s) that I saw as a child.
https://sg30p0.familysearch.org/service/records/storage/dasc...
Re: Radios, how do they work? (2024)
#58Earlier quoted context omitted.
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 ca…
> You can use a germanium diode or even Shottky now instead of a “crystal”. Or a razor blade or a piece of roofing lead and a needle.
Now I’m interested…
Re: Radios, how do they work? (2024)
#59Earlier quoted context omitted.
Take a look at Extra too. You may find that it actually isn't much harder than General. The Extra exam is 50 multiple choice questions broken down by category as follows: 6 Commission Rules 5 Operating Procedures 3 Radio Wave Propagation 5 Amateur Practices 4 Electrical Principles 6 Circuit Components 6 Practical Circuits 3 Signals and Emissions 8 Antennas and Transmission Lines 4 Safety You need to get 37+ correct t…
As I understand it General gets you most everything and Extra is mostly useful for people who want to teach amateur radio classes.
Huh, I never heard that one. Extra gets you more frequency privileges (nice not having to worry so much about band edges) but IMO the real benefit is being able to enjoy reciprocal operating under CEPT when traveling abroad.
Re: Radios, how do they work? (2024)
#60> In today’s article, I’m hoping to provide an introduction to radio that’s free of ham jargon and advanced math …(scroll)… > The identity for cos(α + β) can be trivially extended to cos(α - β), because subtraction is the same as adding a negative number: …(scroll)… > From the formula we derived earlier on, the result of this multiplication necessarily indistinguishable from the superposition of two symmetrical sinus…
This is basic math, not advanced math. If you don't know it, don't worry, you can learn it pretty quickly. Maybe watch some 3Blue1Brown videos and do some textbook exercises and/or game programming. Git gud. There is no royal road to radio modulation. I learned that subtraction was the same as adding a negative number sometime around second grade, and I learned (then forgot) the trigonometric angle-sum identities in…
> Euler's formula
So much EE-related math becomes trivial (or at least not-hard) once you've internalized this formula.
What I am trying to decide is 1) Did I zone out in class when Euler's formula was introduced or 2) Did my secondary school mathematics classes just kind of gloss over it?
I lean towards 2 but unfortunately none of my college classes reintroduced the formula and I ended up making a lot of problems harder than they should have been (I have an EE undergrad).