Three Step Inductor

This three-step inductor consists of a coil of enamelled copper wire wound over an insulated spool. The coil consists of 4 layers of 200 turns each. The tappings at 200, 400 and 800 turns are brought out at 4mm sockets. The output inductances at these tappings are as follows. No. of turns Inductor Resistance 200 0.3mH 0.6Ohm. 400 1.2mH 1.2 Ohm. 800 5mH 2.6Ohm. One can easily change the inductor value of the instrument on just inserting a soft iron core inside the bobbin.