abzza

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  1. Using script with Spectrum on AD2

    @BaffleChallenged - wow, thanks for this! I've recently completed my speaker dummy load, which also includes selectable voltage dividers as you outlined in your document. Very nice. Going to dive into your scripts this evening!
  2. Using script with Spectrum on AD2

    Thanks @attila! Yeah, I'm using the BNC adapter board and some heavy duty, shielded BNC cables for both the AWG and Scope channels - found much cleaner results overall. Thanks for the heads-up though! Busy putting together a selectable 8ohm/4ohm dummy load that can just plug straight into the Analog Discovery via BNC, which will make testing amplifiers much quicker and easier.
  3. Using script with Spectrum on AD2

    Thanks @BaffleChallenged - I did much the same, although I incremented the script 1hz at a time for 20000 readings across the spectrum: for(var idx = 20; idx <= 20000; idx++) // 20hz to 20khz, 1hz increments The script takes about ~10 minutes to complete. Here was the output from a little LM1875 chip kit driving an 8 ohm dummy load. Neat! This was before I added the conversion from dB to % for THD (thanks this website for the explanation!), but it worked out to an average of -62dB, or 0.079% THD. Not too shabby for an eBay kit running in the open air. Another useful addition I added was to average all the THD values to give you a single value to compare against, as well as formatting the output into something more CSV friendly in case the results need to be saved and plotted elsewhere. I'll upload my script changes as well when I'm back at my laptop.