Nikola Tesla - Free-Energy Devices

844 INVENTIONS OF NIKOLA TESLA.combinations there will be, for a given frequency, and consideringonly the fundamental vibration, values which will give the bestresult, with the condenser in shunt to the self-induction coil of;course more such values than with the condenser in series. Butpractical conditions determine the selection. In the latter casein performing the experiments one may take a small self-inductionand a large capacity or a small capacity and a large self-induction,but the latter is preferable, because it is inconvenient to adjusta large capacity by small steps. By taking a coil with a verylarge self-induction the critical capacity is reduced to a very smallvalue, and the capacity of the coil itself may be sufficient. It iseasy, especially by observing certain artifices, to wind a coilthrough which the impedance will be reduced to the value of theohmic resistance only; and for any coil there is, of course, a frequencyat which the maximum current will be made to passthrough the coil. The observation of the relation between self-FIG. 184.induction, capacity and frequency is becoming important in theoperation of alternate current apparatus, such as transformers ormotors, because by a judicious determination of the elements theemployment of an expensive condenser becomes unnecessary.Thus it is possible to pass through the coils of an alternatingcurrent motor under the normal working conditions the requiredcurrent with a low E. M. F. and do away entirely with the falsecurrent, and the larger the motor, the easier such a plan becomespracticable but it is;necessary for this to employ currents of veryhigh potential or high frequency.In Fig. 184 I. is shown a plan which has been followed in thestudy of the resonance effects by means of a high frequency alternator.G! is a coil of many turns, which is divided into smallseparate sections for the purpose of adjustment. The final adjustmentwas made sometimes with a few thin iron wires (thoughthis is not always advisable) or with a closed secondary. The coil