Queries and Answers

What are the dimensions of the core, size of wire and number of turns for a Tesla coil to work with a 6-inch induction coil? What means may be used for regulating the same when supplied with alternating current?

S. J. S.

Tesla coils have no cores and must be very highly insulated. One of the easiest ways of making one is to take a large cylindrical battery jar 8 inches in diameter by 12 inches long, and wind over it about 60 or 80 turns of No. 18 magnet wire. This may then be fixed to the jar by a coating of shellac. The primary should be made of 8 or 10 turns of No. 4 or No. 6 wire, made sufficiently small to slip inside the jar. The whole should be enclosed in a big earthenware tub and filled with mineral seal, linseed or transil oil. For regulation the ordinary means of choking back the current in the primary of the induction coil may be used.