. . .This rule is necessarily only approximate, owing to the way the wires bed on each other from their cylindrical section. In actual practice, when the wire is run through the paraffin bath not more than 50 per cent of the calculated wire will occupy the space. And the thickness of the paper rings must also be added when figuring the total length of the coil. In the iron-clad transformers or induction coils of highest efficiency used in the alternating current electric light system, the rule for determining the windings of the coils is based on the ratio of the turns of wire in the primary to the turns in the secondary, the electromotive force in the primary, and the lines of force cut by the windings.

The secondary ends can be attached to 26binding posts mounted on the reel ends. Unless these reel ends be very high and clear the outside of the coil considerably, it is better to mount the binding posts on the top of the hard rubber pillars. A neat plan is t. . . Read More