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Electrical Engineering, emphasizing analog experience in design and development

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Trap Circuits

Designs are by Joe Miseli.

For NTSC video, the color subcarrier of 3.579MHz always presented a problem for the video, in that that frequency was within the 4.2MHz bandwith of the video itself. As a result, the video path had to have a high Q color subcarrier trap to eliminate the unwanted frequency to keep it from producing noise and distortion at its primary frequency and when it was folded back.

Here are some trap designs and some evaluation

Traps, NTSC Subcarrier

Below is a compensated trap using a bridged T network with some analysis.

Compensated Trap

Below more detailed analysis of a trap.

Trap with Analysis

For analysis of L's and C's, let us consider them primarily in the frequency domain, by use of "s." s translates to jω, where ω (omega) is frequency with an imaginary component (j). An inductor is fundamentally the inverse of a capacitor. A perfect inductor is modeled as sL and a perfect capacitor is modeled as 1/sC.

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See anything that needs further explanation, clarification, or may be in error?

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