# Could a radio detector be built with 12th century tech? **URL:** \ **Category:** Factual Questions\ **Created:** [May 6, 2022, 8:50pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085 "2022-05-06T20:50:22Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 8, 2022, 10:05pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/41 "2022-05-08T22:05:46Z")
> [@dtilque](#): > > Are you suggesting coconuts migrate? They could be carried. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 8, 2022, 10:42pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/42 "2022-05-08T22:42:13Z")
Regarding building the piezoelectric earpiece for your crystal radio receiver: If you could get your hands on a piezoelectric crystal (like a small, thin piece of quartz), would you actually need to turn it into an earphone? I’d think it’d be kind of tough to attach the crystal to a diaphragm, and then enclose that diaphragm in a tiny chamber shaped to go into your ear. Could you tell if you were/weren’t getting a signal by just putting your finger against the piezoelectric crystal and FEELING its vibrations? Or are the vibrations going to be too weak for a normal finger to be able to feel them? (EDIT: Experimentally, when I put my finger on a speaker, I can feel bass notes but not high treble notes. The signal would have to have components to its waveform that were slow enough that you could feel them as vibrations, which is a much lower “highest pitch” threshold than the human ear has.) ---
**Author:** ![Lamoral](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lamoral/32/16078_2.png) [@Lamoral](https://boards.straightdope.com/u/Lamoral)\ **Post date:** [May 8, 2022, 10:55pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/43 "2022-05-08T22:55:05Z")
> [@Marvin\_the\_Martian](#): > > Plus you have to avoid being burned as a witch… Just say that you’re building a witch detector. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [May 8, 2022, 11:12pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/44 "2022-05-08T23:12:17Z")
> [@engineer\_comp\_geek](#): > > They could be carried. It’s a simple question of weight ratios. A five ounce bird could not carry a one pound coconut. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 8, 2022, 11:43pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/45 "2022-05-08T23:43:03Z")
> [@dtilque](#): > > It’s a simple question of weight ratios. A five ounce bird could not carry a one pound coconut. Supposing two swallows carried it together? ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [May 9, 2022, 12:01am UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/46 "2022-05-09T00:01:53Z")
> [@dtilque](#): > > It’s a simple question of weight ratios. A five ounce bird could not carry a one pound coconut. My understanding is that it’s a short three hour tour for coconuts. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 11, 2022, 2:29pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/47 "2022-05-11T14:29:10Z")
Oh, and something else to keep in mind: You know what else they didn’t have in the 12th century? _Soldering irons._ (And actual solder, for that matter.) ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 11, 2022, 2:38pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/48 "2022-05-11T14:38:16Z")
Solder is just lead and a soldering iron is a hunk of metal heated in a fire. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 11, 2022, 3:03pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/49 "2022-05-11T15:03:23Z")
> [@TriPolar](#): > > Solder is just lead I thought lead wasn’t conductive enough on its own, and you had to add other stuff like tin or zinc to make it work right. Maybe you could use pewter? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 11, 2022, 3:12pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/50 "2022-05-11T15:12:47Z")
Commercial solder used to be 60 percent tin and 40 percent lead. Tin has been around since the bronze age and lead has been around longer than that. Ancient Romans confused the two for some reason and called tin “bright lead” and called lead “dark lead”. Not that it matters. The first radio that I built didn’t use solder. You can twist the metal connections together. I used a diode instead of a razor blade (because 8 year old kids shouldn’t be playing with razor blades) and the magnet was a commercial round magnet, No solder required. I wouldn’t say that it worked well, but it worked. The “speaker” was just wire wrapped around the magnet. It was very difficult to hear. Adding a paper cone to the wire probably would have helped tremendously. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 11, 2022, 3:17pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/51 "2022-05-11T15:17:59Z")
Lead is not great but will do the job. If tin is available it would be help a lot. Adding silver would greatly increase electrical conductivity but would also increase melting temperature. A little antimony would help also. But the job can be done with just lead, the conductive surface should be a very thin layer of lead. Any acidic substance could be used as a flux but assuming copper conductors scrubbing down to bare metal should be sufficient by itself. Any kind of flux used might contribute more to corrosion over time. And as @engineer_comp_geek points out, solder is hardly necessary. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [May 11, 2022, 7:07pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/52 "2022-05-11T19:07:46Z")
> [@tracer](#): > > You know what else they didn’t have in the 12th century? > _Soldering irons._ How do you think stained glass windows were made? How do you think all that lead pipe that drove the Romans crazy was joined? Hell, the ancient Greeks had soldering irons, based on the kind of solder joints they made. [![](https://img.youtube.com/vi/T_MdxdGr57k/maxresdefault.jpg "Precision Soft Soldering For Constructing The Antikythera Mechanism - Experimental Archaeology") ](https://www.youtube.com/watch?v=T_MdxdGr57k) ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 11, 2022, 7:21pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/53 "2022-05-11T19:21:05Z")
> [@MrDibble](#): > > How do you think all that lead pipe that drove the Romans crazy was joined? I’d always assumed they used Duck tape. It holds the universe together, after all. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 11, 2022, 7:27pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/54 "2022-05-11T19:27:20Z")
The simplest method of soldering is to pour molten metal on the contact area. I’m sure that’s how they made lead pipes in Rome. They also joined bronze and copper together that way. I don’t know for sure if anyone was soldering iron and steel with lead long ago, it’s not a strong bond like welding, but it works for light duty uses, and when combined with rivets makes a strong sealed joint. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [May 11, 2022, 7:52pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/55 "2022-05-11T19:52:18Z")
> [@engineer\_comp\_geek](#): > > You can twist the metal connections together. And gold can just be squished together. If it starts clean enough, you’ll end up with a better bond than solder. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [May 11, 2022, 10:13pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/56 "2022-05-11T22:13:34Z")
For what it’s worth, the Romans mostly didn’t get lead poisoning from their plumbing. They mostly got it from artificial sweeteners. When you store wine in lead bottles, you get lead acetate, which is very sweet. So of course once someone discovered that, everyone did it, because there’s nothing modern about people liking overly-sweet beverages. ---
**Author:** ![EdwardFound](https://avatars.discourse-cdn.com/v4/letter/e/4af34b/32.png) [@EdwardFound](https://boards.straightdope.com/u/EdwardFound)\ **Post date:** [May 11, 2022, 10:48pm UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/57 "2022-05-11T22:48:09Z")
How are you paying for these supplies? What did you have on your person when you fell into the vortex? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 12, 2022, 1:08am UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/58 "2022-05-12T01:08:30Z")
I never go near a time vortex without a belt loaded with Krugerrands, a Magnum Research Desert Eagle, a Rolex Submariner, and a Duncan Butterfly YoYo. ---
**Author:** ![smithsb](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/smithsb/32/12107_2.png) [@smithsb](https://boards.straightdope.com/u/smithsb)\ **Post date:** [May 12, 2022, 1:24am UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/59 "2022-05-12T01:24:17Z")
It’s the YoYo that will get you drawn, quartered, then burned. ---
**Author:** ![tracer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tracer/32/20578_2.png) [@tracer](https://boards.straightdope.com/u/tracer)\ **Post date:** [May 12, 2022, 6:54am UTC](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085/60 "2022-05-12T06:54:29Z")
> [@EdwardFound](#): > > How are you paying for these supplies? I know where all the gold and diamond mines will be discovered in the centuries to come. Will that mean they’ll be depleted and never discovered, so that I shouldn’t have known about them any more, thus creating a grandfather paradox? Not if you subscribe to the Many Worlds model of time travel! [Previous page](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085.md?page=2) [Next page](https://boards.straightdope.com/t/could-a-radio-detector-be-built-with-12th-century-tech/964085.md?page=4)