While BC547 is not a suitable transistor, it can work on this circuit. The ideal would be the BF494. The beret has 2 + 2 turns of thread 28 or 30 in the form of 1 cm without core.

While BC547 is not a suitable transistor, it can work on this circuit. The ideal would be the BF494. The beret has 2 + 2 turns of thread 28 or 30 in the form of 1 cm without core.