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Step-by-step instructions for making a tunable crystal radio. This is a radio that gets its power from the radio waves. I made it almost entirely from junk except for the diode (1N34 germanium diode) and the earpiece (though you can use a speaker from a phone instead.) The capacitor is made from aluminum foil and a paper towel roll. The coil is rolled on a toilet paper roll. The wire is enameled magnet wire. For the antenna I use a 15 foot wire laid out on the floor. For the earth ground I connect a wire to the ground in the household wiring.

I originally got this circuit from the book "Radio Receiver Projects You Can Build" by Homer L. Davidson.

For this circuit, the diode must be germanium. The following is a partial list of germanium diodes that should work:
1N34A, 1N60, 1N91, 1N119, 1N270, 1N277, 1N283

The following are not germanium diodes and may need a long antenna or a powerful radio station nearby to work:
1N4148 (silicon, found on a lot of circuit boards), B16 (zener diode), 1N5060 (avalanche diode)

The crystal earpiece (piezoelectric earphone) and/or 1N34 germanium diode and/or air core variable capacitors can be ordered from these sources:
http://www.midnightscience.com
https://www.scitoyscatalog.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=SC&Category_Code=R
http://www.maplin.co.uk/crystalearpiece-3256

You can find the circuit diagram shown in this video on this page:
http://rimstar.org/equip/crystal_radios.htm

See also:

How a Crystal Radio Works
http://youtu.be/0-PParSmwtE

Crystal Radio Troubleshooting and Tips
http://youtu.be/HZZmKZJrIW0

Make Crystal Earphone/Earpiece for Crystal Radio
http://youtu.be/OVapqz4yBCY

Use Earbuds/Earphones with Crystal Radio
http://youtu.be/GCh2LVHUavQ

Make a Crystal Radio Coil with Taps
http://youtu.be/Gi9EmhrcfIg

Make Razor Blade Diode for Crystal Radio/Foxhole Radio
http://youtu.be/eIdHsjfbckw

How to Make Crystal Radio Amplifier for Speaker
http://youtu.be/JtPwxbOgBHw

How to Make Amplifier for Crystal Radio Earphone
http://youtu.be/cQ-LxMDrD_o

Steps for How to Make Amplifier for Crystal Earpiece
http://youtu.be/V0dKdSNv_dY

How to Make an AM Radio Transmitter (so you can transmit to your crystal radio)
http://youtu.be/_4-Sx-T6VBc

Amplitude Modulation with Simple AM Radio Transmitter
http://youtu.be/R04yEKqgGPc

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