PASSIVE FM RECEIVER PROJECT

Here is a passive receiver project for the FM band. The image shows better the construction. The variable capacitor theoretically is 5-30pF. I used a 0-70pF porcelain capacitor. These are not too difficult to find compared to the big 500pF variable capacitors used on HF bands.

The coil is a one turn coil wrapped around the variable capacitor in 4 inches diameter. I don't think the diameter of the wire matters.

The type of diode is 1N34, a germanium one. I used a higher voltage germanium diode, but I do not know what would be the difference if I used 1N34.

The capacitor is 0.0001MF (0.1nf or 100pF). I used a ceramic one.

Of course you should not expect any amplification from this apparatus because it is a passive one. The radio wave is directly converted into sound using its own energy. Thus a very sensitive headphone should be used. I used one (electrostatic?) from an old tuner. The more suitable types in my opinion are these that have a coil on the back, which force a metallic plate to produce sound.

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