Description

The plastic ring or bobbin, 162.5 mm overall
diameterwound with three coils of insulated
copper wire with 2,50 and 500 turns mounted on
bakelite moulded platformfitted with 4 terminals,
rotating on a tripod non-magneticmetal base,
supported by levelling screws. Complete with
compass box (Magnetometer) mounted at the
centre ofthe ring.