This 1969 circuit uses two batteries, one of 1.25 and one of 45 or 90 V, thus obtaining a good range. The bobbin has 50 + 50 turns of 2 cm shaped wire 28 without core. The microphone is crystal.
This 1969 circuit uses two batteries, one of 1.25 and one of 45 or 90 V, thus obtaining a good range. The bobbin has 50 + 50 turns of 2 cm shaped wire 28 without core. The microphone is crystal.
