This 1965 Philips circuit uses transistors from the era. Modern equivalent components can be used. The exploration coils must be formed by 550 turns of 0.2 mm wire in a ferrite core.

This 1965 Philips circuit uses transistors from the era. Modern equivalent components can be used. The exploration coils must be formed by 550 turns of 0.2 mm wire in a ferrite core.