This circuit receives the local stations of medium waves listened to in a piezoelectric capsule or crystal phone. The transistor can be a germanium or silicon PNP like the 2SB75, BC558, etc. CV is a variable capacitor taken from an old transistorized medium wave radio. L1 consists of 20 or 30 turns of wire 28 plus 80 turns on a ferrite rod. The antenna is a strand of wire from 3 to 20 meters stretched and grounding is important to obtain more sensitivity. The circuit is from the book Science Fair Projects by Newton C. Braga, published in the United States.
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