Crystal radio question

[Diogenesis]

No. It will change the frequency.
Add a ground.

[elpinta]

How far from an AM station tower are you?

[Sacajaweau]

Try a club that fools with this stuff.

[GeronL]

There is probably a ping list for this.

[Ditto]

Clip it to a water pipe or some other good ground.

[Doogle]

"did it come with a piece of string,a stick,and a piece of flint?"

[djf]

About 30 miles as the crow flies. I’m using the ground off of my home electric wiring.

[Doogle]

http://www.streettech.com/archives_DIY/crystalSet.html

[TxAg1981]

First off, congratulations on your radio. Its very cool stuff isn't it?!
I built some crystal radios when I was younger.
To hear more stations, or to hear them more clearly will depend on a better antenna.
Use a longer wire for your antenna. Adding more windings to the coil will require changes in your capacitor. It is those two that actually tune in the station.
The stations sound faint because their signal strength must overcome the breakdown voltage of the crystal diode. Thus, weaker stations are not heard at all.
Others, please correct me if I'm wrong.

[Army Air Corps]

Actually, I think there is one.

[Joe Boucher]

If you have a spring mattress,
attach the antenna wire to the metal coils
The coils and sheer size helps reception.

[Verbosus]

Quote:
“No. It will change the frequency.
Add a ground.”

I remember my older brother built one when I was real young and you couldn’t hardly hear a thing until my dad hammered a ground rod about a foot or two into the ground outside out window. (There was nothing else handy to ground it to).

[Elderberry]

THE PROJECT CRYSTAL RADIO
(updated 4 Feb 01)

http://bellsouthpwp2.net/w/u/wuggy/radproj.htm

[Dr. Sivana]

I played with the old Radio Shack “P-Box” version of that stuff as a youngster. Don’t expect too much of it.

[Doogle]

Unless you’re in a city, the best time for listening is after sundown. AM wave propagation gets better as the night wears on. Turn off any lights with dimmer switches, as the noise they put out will wipe out any signal you may receive. Computers may generate a fair amount of noise too. Turn the tuning capacitor slowly when looking for stations. Listen carefully. It helps to be in a quiet room.

The best thing about crystal sets is that there’s almost no way to hurt this radio. You can have it wired completely backwards, and since there’s no power supply, you can’t destroy any of the components. The fun thing about crystal sets is that there’s no end to the experimenting. Hundreds of designs and construction ideas have been knocking around for decades. This is only one. By reworking the coil, you can tune other broadcast bands. As long as the transmissions are AM modulated you have a chance of picking them up.

[Steely Tom]

Yes, if you add more turns to the coil, those additional terms will "link" the "magnetic lines of force" eminating from the station; this will increase the amplitude of the signal being rectified by the crystal, which will, in turn, "increase the sensitivity" of the set.

Of course, you have to decrease the capacitance of the tuning capacitor to compensate for the increased inductance of the coil; the inductance goes up as the square of the ratio of number urns in the larger coil to the number of turns in the original coil. Therefore, you have to reduce the size of the capacitor by that same ratio, to pick up the same stations. You can do this, up to a point, by putting another capacitor in series with the tuning capacitor. If you want help in figuring out the size of this offsetting capacitor... ask President Obama, he's brilliant beyond brilliant, unlike myself.

[GOPJ]

Isn’t there something about marking the crystal with a lead pencil to fine tune?

[FrankR]

I remember back in the 50's I found some old documents in my Dad's Navy stuff with a "Stars and Stripes" article on how to build a "Foxhole Radio", using a razor blade, a safety pin and a set of crystal headphones.

I built one and it worked. The blade and the safety pin formed a diode and it was hooked to an antenna and a ground. I remember picking up a couple of stations on it. Of course, it wasn't very loud and tuning it by sliding the pin across the blade was pretty touchy, but it worked.

I found some reference to it on the web.

http://www.scribd.com/doc/7846118/Foxhole-Radio