TCBA Volume 14 - Issue 1
Page 15 of 18
Tesla Coils Resurrected
A schematic wiring diagram of a complete Tesla bipolar high frequency apparatus is shown in Fig. 179, and a glance at this will show you that it is connected up in exactly the same way as the D'Arsonval unipolar apparatus to the high frequency coil itself. The inside coatings of the Leyden jars are connected to the end wires of the primary of the Tesla coil, while the ends of the wires of the secondary form two active electrodes.
How to Use a Power Transformer. - Where you have an alternating current only that is available as the initial source of power, then you can use a power transformer to energize the high frequency coils, instead of a spark coil. A one-quarter kilowatt transformer is large enough for energizing the high frequency coils described above. Where a power transformer is used to energize the high frequency coil, the Leyden jar or other condenser is connected across the terminals of the secondary coil of the power transformer.
Some Experiments With High Frequency Currents.1 - I shall not try to go into detail concerning the experiments you can do with your high frequency apparatus, but, instead, I shall give you an outline of a number of them, which with the accompanying pictures, will enable you to perform them successfully. The experiments that have to do with light can be performed to the best advantage in a dark room. All of the experiments, and many more, can be performed without the slightest danger, as the frequency is so high the current is absolutely harmless.
1 All of the apparatus for setting up high frequency currents and making the experiments can be had of the L. E. Knott Apparatus Company, Boston, Mass.
(1) Let the discharge from the terminal of the high frequency coil strike your hand and you will feel a slight pricking sensation on the spot where the discharge comes in contact with the flesh. (2) Hold an iron rod, or other piece of metal, tightly in your hand and let the discharge strike the latter, as shown at A in Fig. 180, when you will not be able to feel the high frequency current at all.
(3) Hold a Geissler tube in your hand near the discharge electrode, but far enough away so that the sparks will not pass, when the tube will light up. (4) Do the same thing with an ordinary incandescent lamp, or better, connect it to the discharge electrode with a single wire, when it will glow with a green fluorescent light. (5) Place a piece of willimite, which is a mineral, so that the discharge will strike it, when it will glow with a greenish light. (6) Many other minerals and precious stones will likewise be rendered fluorescent under the action of the high frequency discharge.
(7) Connect a brass ball a couple of inches in diameter to the discharge electrode, as shown at B, or you can use a sheet of metal instead, when the brush discharge will produce large quantities of ozone, and this is very refreshing in a sick room. (8) Hold your hand near to the discharge electrode, but still far enough away so that the sparks will not pass between them, and you will get a brush discharge from your hand, as at B. (9) String a bare, or an insulated, copper wire a dozen or fifteen feet long, shorter or longer doesn't matter, from a screw eye in the wall to the discharge electrode, as shown at C, when there will be a luminous discharge all along the wire.