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I'm surprised nobody mentioned radio communication. The AM (Amplitude Modulation) transmission is even quite simple to understand and build. You can even creat

I'm surprised nobody mentioned radio communication. The AM (Amplitude Modulation) transmission is even quite simple to understand and build. You can even create an electric arc between the ground and the transmitting tower as a cheap (and dangerous) receiver: https://youtu.be/uo9nGzIzSPw https://youtu.be/uo9nGzIzSPw

tgv 7y ago
I don't think a layperson can understand even the basic principle behind AM, let alone the actual device. It's not as "simple" as washing your hands.
- irchans 7y ago
  I seem to recall building small AM transmitters in elementary school. I don't remember if I used a transistor or not. I think it was easy to construct the capacitor and the inductor. (I build it in the early 70's and don't really remember how.) We also made crystal diode radios, but I have no idea how to construct a diode from scratch, so maybe those are not simple.
  - artificialidiot 7y ago
    cat whisker detector
    - dublin 7y ago
      This one just requires a lump of germanium and a pin or small wire.
      - stan_rogers 7y ago
        Traditionally, one would have used galena (natural lead II sulfide) crystals. I also recall most "boys'" radios - the type you'd find in Cubs/Scouts/etc. handbooks - using a razor blade as the contact whisker, probably because it was the simplest way to get a small contact point and stiffness at the same time with materials a kid would likely have to hand.
  - mNovak 7y ago
    A pencil tip touching a steel razor blade is famously a diode which can be used to build a "foxhole" radio [1]. [1] https://en.wikipedia.org/wiki/Foxhole_radio https://en.wikipedia.org/wiki/Foxhole_radio
- AWildC182 7y ago
  Back when radioshack existed they used to sell kits where you could assemble a crystal radio out of a handful of simple parts. This was the first real project my dad and I ever did and I was just a little kid at the time.
  - jayess 7y ago
    Wow, that brings back some memories. I built one of those too. It was a crystal radio with no need for batteries. I used that little radio for years to listen in bed until I fell asleep.
  - yellowapple 7y ago
    One of those kits ended up being a growing up story of mine, and a lesson in unchecked hubris. I was maybe 8-ish years old, and trying to follow the instructions to wire together a crystal radio with one of those Radio Shack electronics kits. My stepdad - who had only recently become such, and to my assumption at the time was just some dumb hick mechanic - volunteered to help me troubleshoot. Being the bratty child I was, and being frustrated by my inability to figure it out even with the "easy" diagram (let alone actual schematics, which might as well have been hieroglyphs to me), I snapped back at him "I'm ten times smarter than you!" and stormed off. Not 5 minutes later he calls me back in, triumphantly presenting a working crystal radio. Turns out my "dumb hick mechanic" of a stepfather was actually once upon a time a technician for Nakamichi, and specialized in fixing their receivers. That little crystal radio was trivial compared to the sorts of circuits he used to repair for his day job. That was 20 years ago and he still gives me shit for it, lol
    - nate_meurer 7y ago
      This story just made my evening, thanks.
      - yellowapple 7y ago
        Haha, thanks! The tables did turn on that more recently, when he was having trouble with his computer (an ancient-by-today's-standards Dell Optiplex running Windows XP); his power supply died, so I bought him a new one, but after he installed it he wasn't able to boot into Windows anymore. I figured maybe whatever blew the PSU also blew the hard drive (I've seen that happen before), so next time I was at his place he handed me the tower to take home and diagnose/rebuild. As he's handing it to me, it dawns on me, "Well wait just a second..." On the spot, I popped open the case, took a quick look at the hard drive, plugged in the Molex cable, put the cover back on, and handed it right back to him. Hearing the words "Alright fucker, we're even" made my week.
mynegation 7y ago
Important - yes, but would you consider it simple? AFAIU it relied on Maxwell's equations that I would not characterize as simple.
- kwhitefoot 7y ago
  You don't need to know anything about Maxwell's equations to build a functioning radio. There are plenty of do it yourself books from the 1920s and 30s that explain in great detail how to do it including how to make rectifiers for battery charging, winding coils to get the right inductance, calculating the length of wire needed for the aerial and so on, together with the simple formulae that are needed.
  - stan_rogers 7y ago
    There's reasonably good evidence to suggest that the first radio was invented before there was widespread acceptance of these so-called "waves" that Maxwell's ridiculous maths seemed to predict - before either Hertz or Lodge had managed to prove that they were anything other than artifacts of Maxwell's electromagnetic model. A certain David Hughes demonstrated transmission over a distance, but it was just written off as induction. And one could even presume that radio would have been inevitable, even without a preexisting theory of it, based entirely on barometers lighting up in thunderstorms; it only needed Volta's pile or a simple generator - some source of current on demand - and some experimentation with electricity before the phenomenon was noted and then deliberately employed.

tgv 7y ago

I don't think a layperson can understand even the basic principle behind AM, let alone the actual device. It's not as "simple" as washing your hands.

irchans 7y ago
I seem to recall building small AM transmitters in elementary school. I don't remember if I used a transistor or not. I think it was easy to construct the capacitor and the inductor. (I build it in the early 70's and don't really remember how.) We also made crystal diode radios, but I have no idea how to construct a diode from scratch, so maybe those are not simple.
- artificialidiot 7y ago
  cat whisker detector
  - dublin 7y ago
    This one just requires a lump of germanium and a pin or small wire.
    - stan_rogers 7y ago
      Traditionally, one would have used galena (natural lead II sulfide) crystals. I also recall most "boys'" radios - the type you'd find in Cubs/Scouts/etc. handbooks - using a razor blade as the contact whisker, probably because it was the simplest way to get a small contact point and stiffness at the same time with materials a kid would likely have to hand.
- mNovak 7y ago
  A pencil tip touching a steel razor blade is famously a diode which can be used to build a "foxhole" radio [1]. [1] https://en.wikipedia.org/wiki/Foxhole_radio https://en.wikipedia.org/wiki/Foxhole_radio
AWildC182 7y ago
Back when radioshack existed they used to sell kits where you could assemble a crystal radio out of a handful of simple parts. This was the first real project my dad and I ever did and I was just a little kid at the time.
- jayess 7y ago
  Wow, that brings back some memories. I built one of those too. It was a crystal radio with no need for batteries. I used that little radio for years to listen in bed until I fell asleep.
- yellowapple 7y ago
  One of those kits ended up being a growing up story of mine, and a lesson in unchecked hubris. I was maybe 8-ish years old, and trying to follow the instructions to wire together a crystal radio with one of those Radio Shack electronics kits. My stepdad - who had only recently become such, and to my assumption at the time was just some dumb hick mechanic - volunteered to help me troubleshoot. Being the bratty child I was, and being frustrated by my inability to figure it out even with the "easy" diagram (let alone actual schematics, which might as well have been hieroglyphs to me), I snapped back at him "I'm ten times smarter than you!" and stormed off. Not 5 minutes later he calls me back in, triumphantly presenting a working crystal radio. Turns out my "dumb hick mechanic" of a stepfather was actually once upon a time a technician for Nakamichi, and specialized in fixing their receivers. That little crystal radio was trivial compared to the sorts of circuits he used to repair for his day job. That was 20 years ago and he still gives me shit for it, lol
  - nate_meurer 7y ago
    This story just made my evening, thanks.
    - yellowapple 7y ago
      Haha, thanks! The tables did turn on that more recently, when he was having trouble with his computer (an ancient-by-today's-standards Dell Optiplex running Windows XP); his power supply died, so I bought him a new one, but after he installed it he wasn't able to boot into Windows anymore. I figured maybe whatever blew the PSU also blew the hard drive (I've seen that happen before), so next time I was at his place he handed me the tower to take home and diagnose/rebuild. As he's handing it to me, it dawns on me, "Well wait just a second..." On the spot, I popped open the case, took a quick look at the hard drive, plugged in the Molex cable, put the cover back on, and handed it right back to him. Hearing the words "Alright fucker, we're even" made my week.

mynegation 7y ago

Important - yes, but would you consider it simple? AFAIU it relied on Maxwell's equations that I would not characterize as simple.

kwhitefoot 7y ago
You don't need to know anything about Maxwell's equations to build a functioning radio. There are plenty of do it yourself books from the 1920s and 30s that explain in great detail how to do it including how to make rectifiers for battery charging, winding coils to get the right inductance, calculating the length of wire needed for the aerial and so on, together with the simple formulae that are needed.
- stan_rogers 7y ago
  There's reasonably good evidence to suggest that the first radio was invented before there was widespread acceptance of these so-called "waves" that Maxwell's ridiculous maths seemed to predict - before either Hertz or Lodge had managed to prove that they were anything other than artifacts of Maxwell's electromagnetic model. A certain David Hughes demonstrated transmission over a distance, but it was just written off as induction. And one could even presume that radio would have been inevitable, even without a preexisting theory of it, based entirely on barometers lighting up in thunderstorms; it only needed Volta's pile or a simple generator - some source of current on demand - and some experimentation with electricity before the phenomenon was noted and then deliberately employed.