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R/E/P => R/E/P Archives => Bruno Putzeys (Designer) - Dave Hecht (Master Tech) => Topic started by: J.J. Blair on June 30, 2008, 01:39:28 AM

Title: frequency analysis for resistors
Post by: J.J. Blair on June 30, 2008, 01:39:28 AM
I want to do some type of harmonic analysis or what not, and see if I'm in fact hearing what I think I'm hearing, with different types of resistors.  Something like where I can run a square wave though, and see if the shape changes, or run a tone and look for harmonics.  

What would be the best way to set this up?  Run tones through a U pad?

Or how about something similar for capacitors?

Any ideas?
Title: Re: frequency analysis for resistors
Post by: bruno putzeys on June 30, 2008, 03:29:05 AM
Linear distortion (the kind of thing you see with a square wave) is dominated fully by the inductance and capacitance of the part and is rarely of interest. Nonlinear distortion (harmonic distortion) can vary wildly. Metal film resistors have negligible distortion but distortion in thick film carbon chip resistors sometimes borders on the spectacular (I've seen 0.01% at a few volts). To measure this distortion, build an inverting amplifier using a good opamp (LM4562), one "known good" metal film resistor (the feedback resistor) and one "test" resistor (the input resistor).