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adjust freq Tesla
Posted by John Carter on 11/10/2006, 9:53 am
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Re: adjust freq Tesla
Posted by Bert Hickman on 11/10/2006, 10:39 am, in reply to "adjust freq Tesla" Hello John, To my knowledge, no. A true Tesla Coil uses a tuned secondary circuit consisting of a secondary coil (inductor) and a HV terminal (typically a toroid or sphere) that provides additional capacitance. The combination of the secondary's self-inductance and self-capacitance, and the topload capacitance will oscillate at a preferred frequency (called the fundamental or operating frequency of the coil). The primary circuit of the Tesla Coil is then tuned to the same frequency. While it is easy to tune the primary circuit of a Tesla Coil by changing the primary capacitance or by "tapping" the primary winding in order to adjust its inductance, it is not simple to change the secondary's operating frequency. The secondary inductance is pretty much fixed by the geometry of the winding and the number of turns. The topload capacitance can be increased slightly by raising the height of the topload, or by moving conductive objects closer to the secondary, but the resulting frequency change is typically less than 5%. I suppose that clever ways of increasing secondary inductance (perhaps by using an adjustable ferrite core), or topload capacitance (using an "expandable" topload to increase it's diameter) could significantly increase the frequency range, but I am unaware of any coils that have actually used this technique. However, it would be relatively simple to generate high voltage RF using a variable power oscillator and an RF transformer. While not a true Tesla Coil, this setup would be capable of generating high voltage at variable frequencies. Whether this is feasible for your needs depends on your required output voltage, power, and frequency range. What is your application? Bert
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