Re: [TCML] high voltage capacitor

[Quarkster <quarkster@xxxxxxx>]

Matthew -

You will need to know exactly what you are trying to do before you can make any determination of what type of capacitor will work in your application.

1. You are designing a "coil". You mean a Tesla coil?

2. If so, what type of Tesla coil are you designing? Conventional spark-gap coil? Solid-state coil? Vacuum-tube coil? SISG coil? Something completely new and different?

3. You mentioned that you are "designing for low frequency, around 20,000 Hz". Have you actually done any preliminary design work that would give you some idea of the inductance and capacitance values (and the associated physical size of the components) required to resonate at 20 KHz? 

4. A frequency of 20 KHz is at the very top end of the range of normal human acoustic perception (ultrasonic range) and not into the realm of Radio Frequency. What are you trying to accomplish by designing a 'Tesla coil" with an operating frequency of 20 KHz? 

5. In the capacitor world, 20 KHz is not "low frequency"; 50 or 60 Hz is. If a capacitor is carrying any significant current (like in a Tesla coil tank circuit or a switching DC power supply), even if you were able to build a coil that operated at 20 KHz the capacitor would require a low-loss dielectric just as if the coil operated at RF frequencies.

The TCML Archives at www.pupman.com contain 16 YEARS of searchable discussions on Tesla coil design and capacitor selection. It might be very useful to spend some time reviewing the information in the Archives and getting familiar with Tesla coil design and construction before you get too far into designing a 20 KHz Tesla coil. 

Also,  Richie Burnett's website at www.richieburnett.co.uk/tesla.shtml is still the world's best one-stop source for information on the Theory of Operation and the Design of Tesla Coils, and anyone contemplating building a Tesla coil should study the informatiopn presented here until they have a good understanding of how a Tesla coil operates, the function of each part, and the basic design requirements for achieving resonance.

Regards,
Herr Zapp


--- On Wed, 5/13/09, Matthew Boddicker <shmerpleton_town@xxxxxxxxxxx> wrote:
From: Matthew Boddicker <shmerpleton_town@xxxxxxxxxxx>
Subject: [TCML] high voltage capacitor
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Wednesday, May 13, 2009, 9:06 AM

I am in the design phase of a coil and I need advice and capacitors. What are
the best capacitors for high voltage applications? I need a voltage rating of
40,000Volts and high capacitance if possible. They don't need to be high
frequency (designing for low frequency, around 20,000Hz).

 

Take care,

Matthew Boddicker

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