crystal radio: the first real free energy device

[TinselKoala]

Thanks, the coil set is called a "variometer" and has quite a good tuning range by rotating the inner coil. The inner and outer coils are in series, with contact made in the pivot points. The radio is a version of the so-called "aussie radio" that I found on a Crystal Radio website. Lots of really nice ones there.
I did some research and found that the phosphor bronze wire is supposed to be the best whisker material, it is stiff enough to make a good contact with the galena and holds a sharp point well, and it's the material most wrapped classical guitar strings use for the "wrapping" so it's easy to get a bit from an old, or even new string. I have to use a little pressure, not too much, for the contact, and probe and scratch around for a while to find the best spot. I think that the key is to find a single "diode junction" on the surface of the galena, usually it is in a crevasse or ledge in the crystal. My crystal is a chunk from a not-very-nice "mineral sample" sold to kids for their rock collections. It's embedded in ordinary solder, in a little copper pipecap. Hard to get it to stick properly in the solder, it floats in the molten solder!
I haven't measured the voltage from the galena itself, this is a tricky measurement to make because of the sensitivity of the whisker adjustment. I feed the output into a small stereo amp (mono mode) and the sound fidelity is every bit as good as from a standard powered AM radio tuner. Or use the piezo element or high-impedance headphones for truly "no power" operation. I was amazed when I first put the LED on the output, so I soldered it into the circuit permanently. Sometimes I get the LED bright without hearing any audio modulation, that's strange because I don't know what I'm picking up then.

That's a sweet looking set! Damn clever coupling system too.   I have a slinky somewere ... I've made only two batches of synthetic galena , undoped and set in woods metal.
In the lab, using a nearby signal generator , they produced less voltage on the cap when compared to the diode. I used a very thin strand of copper as the whisker. Any pressure at all and it conducted both ways. I need to try them on a radio signal to be certain before I change the synthesis. Do you need any pressure on your galena? Also, have you measured any shorted I or open v from the galena

[pomodoro]

Great info,now I know what a variometer looks like! I will chase down some cheap strings on eBay. Meanwhile I will see if a pn junction in a 2N2222A with its can filled with UO2 does anything out of the ordinary. I just found my stash of 1960s germanium semiconductors. From memory they have some liquid inside, unlike the modern one I just did.  I will find out tomorrow.  According to the Moreland patent an audio amplifier with such a modded transistor melted the speaker with all extra power !!! I may need to invest in 1000w speakers before I attempt the experiment 

[profitis]

Take a saturated solution of uranium nitrate on some gold or platinum foil.touch a chunk germanium direct onto it(the solution) and see if you get a circuit pomodoro.at least the uranium will be intimately incontact.compare with saturated magnesium nitrate sol.

[Pirate88179]

I have always wanted to make one of these but had no place in my apartment outside to string an antenna.  TK just solved that with the slinky idea...brilliant!  I can run it up near my ceiling.

About 5 years back, I bought some germanium diodes but, there is no number on them.  I believe they were what was recommended for my first Bedini set-up. (I have to look up on the schematic to see what was called for)  Will one of these possibly work in making a crystal set?  If so, I have every thing I need to make a simple one.

Bill

***EDIT***  I looked it up.  The germanium diodes I have are supposed to be 1N4001

[TinselKoala]

I have always wanted to make one of these but had no place in my apartment outside to string an antenna.  TK just solved that with the slinky idea...brilliant!  I can run it up near my ceiling.

About 5 years back, I bought some germanium diodes but, there is no number on them.  I believe they were what was recommended for my first Bedini set-up. (I have to look up on the schematic to see what was called for)  Will one of these possibly work in making a crystal set?  If so, I have every thing I need to make a simple one.

Bill

***EDIT***  I looked it up.  The germanium diodes I have are supposed to be 1N4001

Whaat? 1n4001 is a silicon diode, a 50 V, 1 A rectifier diode. Usually in a plastic DO-41 package. Very not likely to work in a Crystal set.

Most modern era (within the last 50 years, say) germanium diodes are in clear glass packages. They are usually "point contact" devices and you can see (with a magnifying lens) inside the glass to see the little whisker thing from the Anode side making a point contact with the little chunk of germanium on the Cathode side. They will have low forward voltage drops, like below 0.3 V when checked with the Diode Check function of your DMM, usually. (The exact value will depend on your meter, but will usually be half or less of what a 4000-series rectifier diode will read.) Schottky diodes will also have a low forward voltage drop but aren't suited for Crystal Radios in spite of that, except for some special ones. Special, meaning none that I have or can easily get!

By coincidence this topic is also being discussed on OUR. I tested a few of my diodes and reported there just this morning.

There are lots of 1n34a germanium diodes being advertised on EBay, from China, with really low prices. It would be interesting to see if they are genuine.
These at least have a picture that _looks_ like a genuine germanium point-contact diode.... some other listings don't.
http://www.ebay.com/itm/10-PCS-GERMANIUM-DIODE-1N34A-DO-7-1N34-IN34A-/140769037475

I have a few genuine point-contact 1n34 or 1n34a and 1n60, and they measure 0.249 - 0.270 Vf on my diode checker. I found one that measures 0.247, it is marked "12101 3CT". Another has no numbers but has black, gold, red and green color bands and measures 0.257 Vf.

For comparison, a 1n5711 Schottky measures 0.372 Vf and a 1n4148 measures 0.686 Vf, and a 1n4004 rectifier gives 0.600 Vf.

I have some marked 1n270 gold-bonded Ge point-contacts pulled from old TV chassis, they measure 0.252-0.258.

But a 1n5817 Schottky measures 0.181 !!  Testing four others from that batch: 0.178 -0.182 Vf.  A 1n5819 gives 0.220.
Retesting a 1n270 gives 0.256, same as before.

I'm going to try one of those 5817s in my crystal set right away!

Meter is El Cheepo XL830L with smoothjaw gator clips as probes for good contact.

And this testing was all stimulated by an article here:
http://baec.tripod.com/articles/crystal.htm