Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>Thanks Gary, appreciate the references you give out. I can understand why Tesla increased the inner spacing. Hope I won't have to do the same, but easy enough if I do. I finished the form today, so now just a matter of installing the plexi standoff runners (which is inset into the provided grooves). Then it should be ready for wire!
Here's a photo of the form. http://www.classictesla.com/flat/Img_3002fast.jpg (dial up) http://www.classictesla.com/flat/Img_3002.jpg (original image, large file) Take care, Bart Tesla list wrote:
Original poster: "Gary Peterson" <g.peterson@xxxxxxxxxxxx>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx> . . . There are many ways to implement the primary (outer edge or anywhere below the primary). Thus, high coupling can be achieved with a "much" larger airgap than used on a classic 2 coil system. . . . For example, take this new flat secondary and place a 2 turn primary 5" below it. . . . BartOnce again, while you are probably already aware of this I want to point out that the lecture "High Frequency Oscillators for Electro-therapeutic and Other Purposes," Electrical Engineer, November 17, 1898, includes material that is relevant to your project. For example,"When it is desired to use small currents of high tension, a secondary coil is resorted to, as illustrated in Fig. 2. (see http://www.tfcbooks.com/images/articles/1898-11-17/figs_1234.gif ) I have found it from the outset convenient to make a departure from the ordinary ways of winding the coils with a considerable number of small turns. For many reasons the physician will find it better to provide a large hoop H of not less than, say three feet in diameter and preferably more, and to wind upon it a few turns of stout cable P. The secondary coil S is easily prepared by taking two wooden hoops h h and joining them with stiff cardboard. One single layer of ordinary magnet wire, and not too thin at that, will be generally sufficient, the number of turns necessary for the particular use for which the coil is intended being easily ascertained by a few trials. . . . Additional advantages . . . will be found in the perfect regulation which is effected merely by altering the distance between the primary and secondary, for which adjustment provision should be made, and, furthermore, in the occurrence of harmonics which are more pronounced in such large coils of thick wire, situated at some distance from the primary.Two things are again made apparent from this particular description, 1) the central axis of the two inductors is horizontal, and 2) coupling between the coils is adjustable, with the primary being fixed in position and the secondary being moveable.You can find the entire text of the lecture along with its illustrations posted at http://www.tfcbooks.com/tesla/1898-11-17.htm .I also want to point out that Tesla modified his 8-foot flat-spiral secondary in or before 1898 by doubling the spacing of the inner turns, as can be just seen in the 1901 Houston St. lab photo at http://www.teslascience.org/archive/descriptions/picture07.htm .Regards, Gary