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)
I had some links to website for the crystal earpiece (piezoelectric earphone) and/or air core variable capacitors but their websites went away. If anyone has link, feel free to leave a comment and I'll add them here. The 1N34 germanium diode can be found on:
https://www.ebay.com/
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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