A Crystal Radio is the most basic design for listening to Amplitude Modulated (AM) radio station.

Crystal radios get their power from the radio signal themselves. There's no need to supply batteries.

The only parts not homemade are the germanium diode and the crystal earpiece or crystal earphone and the copper wire for the coil connections and antenna.

Make your own working Crystal Radio Receiver for a traditional medium wave radio, powered by a crystal (no batteries required!)

You will be able to listen to your favourite medium wave radio stations on something you've made yourself!

What is a Crystal Radio Set

tunable crystal radio diagram

Homemade Crystal radio

To build this circuit I suggest you buy a germanium diode like an 1N34 or 1N60P but if you have the patience and really want to make a working diode yourself there is a way to make one using a razor blade and a pencil.

1N60P Germanium Detector Diode for AM Radio Detection can be got cheaply from Amazon post free

You will need to buy some bare copper wire

How a Crystal Radio Works

One way of connecting to a ground is to connect to bare part of a water pipe or to a central heating radiator on an earthing wire.

This design will be much clearer to hear if by the addition of a single transistor circuit as an amplifier and a battery to power the amplifier.

How to Make/Build a Crystal Radio

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.

Originally this circuit came 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 :

http://www.midnightscience.com or ebay

Or a complete kit can be got from Amazon

DIY AM Radios (using IC amplifiers)

DIY AM crystal radio