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Re: gEDA-user: terminators

gene glick wrote:
> Steven Michalske wrote:
> 
> Hey Steven, that's a pretty interesting analysis.  I just want to add 
> something from Dr. Howard Johnson's book on this stuff.  His claim is 
> that you can treat a pcb trace as a lumped system if the trace is less 
> than 1/4 * 'length of the edge'.  

[jg]I think HJ might have meant length of the ramp up or ramp down when he said "edge".
	I can't see how length of a square wave half cycle translates to fractions of wavelengths
	at some resonance...which is where "1/4 * 'length of the edge'" must come from.

Well, at 170 ps/inch the length of the
> edge is about 5.8" - that's exactly 1/2 your result.

  11.7
> inches/cyle * 0.5 cycle = 5.8"

John
-- 
Ecosensory   Austin TX


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