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Re: [TCML] Terry filters

On Jan 1, 2008, at 7:43 AM, Dave Goodfellow wrote:

Thanks for your well thought out reply to my comparison of low pass filters (as used in audio) to transformer protection. Now it is clear to me the basic flaw of using chokes on our NST's.

Best regards, Dave Goodfellow

----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx>
Sent: Monday, December 31, 2007 9:21 PM
Subject: RE: [TCML] Terry filters

Hi Dave,

Your analogy about using just an inductor for a woofer low pass network made me think hard for a moment about my post. You are exactly right about the requirements for 6/12/18 dB/octave filters. But the woofer situation is very different than NST protection networks and I maintain my position. Allow me to explain.

In the woofer circuit, the load, the speaker, is an 8 Ohm resistor, and forms an integral part of a 1-pole R-L network. There is some inductance in the woofer, but it's predominantly resistive; otherwise it wouldn't consume power.

What?!? Hang on a minute. The woofer is doing _work_! Your statement suggests that a motor wound with superconductor (all inductance, no resistance) and delivering 1 HP to a load would consume no power!

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