|
diyAudio Member
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
|
The sound card impedance tester is here
discussed in the most recent edition of the ham radio magazine QST (with a more scientific discussion in QEX it's companion mag.)
The LMS test set uses a dual opamp to compare the voltage drop across an unknown impedance and an acurately known resistor. It is remarkably simple.
You can test inductors, capacitors, transformers, negative impedances, etc.
A PDF of the QEX article is available at www.arrl.org/qex/2005/Steber.pdf
the code can be downloaded at
http://www.arrl.org/files/qst-binaries/
just look about 1/3 down the page
you may need to run
VBRun60sp5.exe (availbable at Microsoft Downloads) if you get the error message "Required DLL file MSVBVM60.DLL was not found"
Jack
edit: I should have credited the author of the article -- Dr. George Steber, WB9LVI, Prof. Emeritus of EE at the University of Wisconsin, Milwaukee.
|
