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+ ~50 yards of telephone wire for an antenna, and an AK47 bayonet driven into wet soil for my ground. Using a piezoelectric earpiece, no batteries, just the antenna to pick up enough energy to hear it.

All I could get was a Spanish language station from who knows where (OKC, 120 miles away?), but I was set up way out in the mountains.

Anybody have any good setups?

That's really cool OP. All I have other than an old radio that has some short wave bands is a chicom ht and a 10 meter in my truck.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311.R4.TR12.TRC2.A0.H1.Xcrystal+radio.TRS0&_nkw=crystal+radio+kit&_sacat=0

No batteries ?
The antena just picks up energy thru the air . Sounds Tesla like.

Sorry I double tapped

as I understand it, in lay terms,  you use the LONG wire to collect electromagnetic energy and if you do it right, there is just enough electricity generated to make a little tiny earpiece speaker make just enough noise to hear it.

The boys in the trench would make them out of all kinds of stuff.  AM radio and knife sticking in the dirt isn't the best ground, but it's part of the mystique.

the "one way valve" is the tricky part, I cheated and used a diode, but in the war they would use all kinds of weird stuff,  a razor blade and a needle were often used.

I tried winding my own coil using spliced together telephone line... but it failed. I just used the coil that came with the kit.

They never show the antenna in these kits, but it's just a really long copper wire, hung sort of high.

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Crystal radio

https://en.m.wikipedia.org/wiki/Crystal_radio

Thats pretty cool .
A long wire laying on the ground !

They tended to lay them on the ground in the war, but back then the stations were nearby and powerful, the propaganda stations would play music and entertainment to each other's sides, all along the front. The trench radio was very common. There are really  fun experiments.  Doing some more reading, looks like my homebuilt coil failed cause I left the insulation on it.

I know where this is headed...

Time for version 2.0

ETA: good reading here https://bizarrelabs.com/crystalradio.htm

when electrons move on the surface of a wire they generate electromagnetic waves at right angles to the direction of the electron flow.... when electromagnetic waves pass through a wire they generate a flow of electrons (electricity) ...the "carrier" wave can be changed up/down (AM) or side to side (FM) to add intelligence to the wave.... the adjustable coil "trims" the length of the antenna to catch a wave of a particular frequency (wave length and frequency are related to the speed of light)  the diode, germanium crystal, razor blade etc allows the electricity to only flow in one direction so the modulated information on the signal can be received by the ear phone

Had one when I was a kid. never got it to work.

my first try didn't work either.

keep on keeping on. You CAN do it!

found my antenna today, forgot i only had a ~25' piece of telephone cable, so cut it apart and soldered it end to end to get it to 100 feet. It's rainbowish color

I swear this time I'm going to do it the right way, Germ diodes are only ~$1 and resistors are only ~$1, I'll even splurge and get some resin coated copper wire for a real coil!

I found out only one company in the world (in England) still makes the style of ear piece you need and it's a randomly bad piece of crap.

England has a strong DIY radio presence on ebay It's been that way for years. WTF is up with that?

the Boy's Life magazine (Boy Scouts) had plans for one when I was a kid... the coil was wrapped around a round Quacker Oats container, .... I gulped down a lot of oat meal to get that stinking tube

you need a good ground rod... once upon a time most homes had galvanized pipe for cold water and you just clipped on with an alligator clip... today you will probably need a dedicated ground rod

The quaker oats plans are still on the net.

I'm hoping pvc pipe will work better though.

I saw one video where the ground from a house plug in was being used, NOT going to teach the kids that trick though.

I'm thinking my first coil failed because I didn't control for the size of the tube I wrapped the wire around (juice concentrate). I'm still learning the basics. Wire size and tube size apparently determine the number of coils needed, who knew?

http://www.crystalradio.net/cal/indcal2.shtml

Got it working today though,

For ground I drilled a hole crosswise in each end of a 4 foot piece of rebar, threaded a bare copper wire though the holes then soldered the bottom hole (plumbing torch) and drove it in the ground next to the bedroom window, took up the slack and soldered the top hole, then finished driving it in, leaving about 4 inches of wire sticking up. I poured a gallon of salt water on it too, just to be sure.

For an antenna I took ~100 feet of barbless fence wire and strung it up between the garage and a cedar tree, using a short piece of 1" outdoor pvc on each end for insulation, goes right by the bedroom window so I can listen from indoors. It was the longest run I could make without doing weird stuff like L shaped or inverted V magic. I ground off the galvanization and soldered a piece of copper wire to it to make sure my connection was strong, the connection is about 1/5 of the way along the wire, I'm not sure that's ideal, I think it's supposed to work better on the end, but I can disconnect the whole thing in seconds.

Still using the crystal radio schematic from the 200in1 book. But some germanium diodes, 47k resistors and 26 gauge magnet wire will be on my ebay card soon. I actually have a big chunk of Galena somewhere, IDK where I even got it, and had no idea it was perfect for a radio until yesterday.

I am able to selectively tune several AM stations using the variable capacitor and different taps. Unfortunately my hand interferes, so I have to adjust a little at a time then back my hand off to check the results.

Playing with different taps and the kit capacitors and variable capacitor was interesting, I also tried using a homemade book capacitor, worked pretty good,.

Most interesting is that a slight mistake in the wiring sometimes made no difference, and weird stuff happens when you start rearranging wires, sometimes with good results.

So many different ways to make it work (even on accident), but one tiny mistake and it doesn't work at all.

Also amazing that humans discovered this stuff 150 years ago.

The homemade stuff is very cool, so many ways to make a capacitor. Nests cups, DVDs, Books. Imagination is the limit.

For the resistor, I'm thinking copper wire around a nail?

The detector is the second hardest part, but figure I'll get good at the rest and save building a detector for last, once I know I can get a working radio.

The ear piece is looking to be the hardest part to make from scratch,  not going to try and tackle that any time soon.

Looking to use aluminum duct tape for the next variable capacitor, wrapped around a pvc pipe, then plastic film from a page cover, then wrap more aluminum tape. Should work great and be classy-ish looking and be weather resistant.

I plan on making the whole thing on a piece on 1-1/4" pvc pipe. (maybe in a U shape or square shape.) with coil on one side and variable capacitor on the other. It should float and be water resistant when I get done.

I suppose it could come in handy during the next ice storm (or 'nader) when all the electrics go down (again).

Modding it for shortwave radio reception will be the next challenge.

best tutorial ever

I built a foxhole radio when I was in Iraq, with scraps located around camp (lid from a coffee can, pencil lead detector, network cable wrapped around a toilet paper tube for a tuning coil, old razor). I'll have to see if I can find pics.

Not sure the world is ready for it... butt fuck it?

I can't find the picture, but it's an old man in ~1920 smoking a pipe that is also a crystal radio, his hat had the coil, IDK if he had an antenna, as his hat was "really big" ~~lol~~

Looked like a 2 foot diameter, 4 sided spider web on a hat.

Now we have this.

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Maybe as a necklace or incorporated into something else. Two for one at that price!

One of those with a spool of magnet wire and an ear piece, and two aligator clips on short leads in an altoid can would be slick for an emergency radio (for real emergencies).

Obvious next step is an AR-15 rifle incorporating an AM/HAM crystal radio. Buttstock will hold a spool of the paracord that has a wire in it. Ground will be up to operators who operate operationally, perhaps pee in the dirt and stab a knife in it. Maybe bayonette in dead terrorist instead, pool of blood in dirt will provide good ground. Add urine as needed.

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1-1/4" pvc, telephone hardline for the coil, scratch built variable capacitor made from aluminum duct tape.

only thing I'm using from the kit is the germanium diode and a 470k resistor (need to order some parts, stat)

coil is 25 +100 with taps every 10 turns, no idea the gauge but very small.

Took a little tinkering to find a capacitor profile that works well. Not happy with the wax paper between layers, plastic baggies worked also, but didn't look classy. I need to get some plastic page covers and try those.

Sensitivity and selectivity is very good, I'm able to get several stations  with minimal to zero secondary stations audible, it can be tuned (almost) loud enough to hurt the ears, when I added the kit's variable cap to the antenna it lowered the volume but made certain stations get super clear.

IDK what I was thinking, but the copper wrapped nail didn't have nearly enough resistance, need to try something different homemade high value resistors

The black coil of wire sticking off the capacitor slider is there to pull on to tune the capacitor. I also reinforced the slider with several layers of aluminum tape where the wire connects. Eventually I need one that bolts together. It's a work in progress, will likely use a different set up in the end, maybe some plates hidden inside the tube that move via knob/thumbscrew on the end. I'm just happy it's working so far.

Just to note I'm using the schematic in the "how a crystal radio works" tutorial above.

Today's adventure was resistors.

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Started with a short pencil lead soldered to wire, only got about 10 ohms? Full length gave about 100 ohms, the electromagnet did nothing as far as I could tell, Basing that off of audio strength.

I didn't have 1000 pencils, nor time to wait for glue to dry (grind up graphite (or find the lock lube) and mix with elmer's glue), so on to something else. I pondered carving the graphite down to smaller diameter in the middle, but figured it would be too fragile, if it even worked.

I seem to remember reading about WW1 radios years ago and that metal -paper -metal + clamp forms a resistor, as paper has a very slight conductivity. But I'm not certain that it isn't acting as a capacitor, as some radios use a capacitor in the same location. It can't be both. (can it?) I suppose any capacitor with leakage is acting like a resistor, maybe?

When clamping nickels/pennies be sure to sand it smooth on the contact surface to prevent the paper from getting cut, as I learned the hard way.

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Insulation for clamp is plastic milk jug, with two sheets of notebook paper between the nickles. The (resistance?/capacitance?) is adjustable by clamping force.

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It may work better with more or less paper, but that's all I've tried so far.

Clarity and volume are both increased, and there is almost no static when using this addition (vs nothing).

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All that's left is the homemade detector.

Soon as I run across my galena (or ebay gets here with my diodes) it will be a standalone unit and I can start hiding wires beneath the pipe, and switch to plastic film instead of wax paper, it's starting to roll on the edge from constant tuning. The vice grips will be replaced with a homemade mini C clamp, using a short bolt and nut. An AK47/SKS front sight adjustment tool might be perfect it it was mounted properly.

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So, here is what I thought was the finished product,

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then I added a 47k resistor and it became crystal clear, and made the nickles superfluous.

So they went bye bye, maybe if I was using a galenium crystal I would keep them. Building these sets may be addictive, I can already see it coming.

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Here is it set to the local country western station, it can tune about as good as my weather radio.

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these cheap "1N34A Germanium Diode DO-35 DO35 1N34" from ebay are crap, after some reading I discovered the problem with crappy diodes is apparently widespread. First one I tested I thought it wasn't working at first, then I figured out I could stack them parallel.

My old radio shack kit has a bad ass germanium diode, its also a lot bigger.

Took ~5-6 of the new ones to get an equivalent signal, so I wired all 10 together.

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It's now so loud my ear was ringing after a session I'm going to need a volume control: Plan A- feed it to x4 earpieces to reduce the volume, and so everybody can listen at once.

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