The transistor of this circuit can be 2N2222 or BF494. The coil can have 2 to 8 turns of wire 22 to 26 in the form of 1 cm in diameter without core or self-supporting. CV is a 10 to 20 pF trimmer with maximum capacitance and all capacitors must be ceramic. An antenna can be placed on the collector of the transistor for the emission of signals. The circuit is from the book Science Fair Projects by Newton C. Braga.
