Hi
Is named Documenti ( in italian) maybe because my Windows is in Italian
W
Also for “Utenti” in english Users
I have tried to male a folder as Documents but the system says that a folder Documenti ( italian ) exist so is not possibls to do this
Walter
Ok that’s just bizarre. I don’t have the word Documents but instead use this multi-language function:
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
According to Microsoft’s documentation the folder name is Documents but the Windows File Browser shows it to you as Documenti (seriously). For some reason (duh) this is failing. I’m sure I can fix it, thanks for reporting it.
Mark
My system also shows different (system language) name for Documents (Dokumentit) and I have no issues with the .cfg file.
@timoj thanks for the confirmation
Yes, I just switched to Italy/Italian and had no issues at all, despite the browser insisting the folder was Documenti
I think this is more likely an antivirus or something like that. It’s not QA40xPlot though.
Mark
Hello Mark,
I installed the Qa40xPlot app., and now have a more credible response when I use a long FFT and the maximum smoothing.
I am still not sure of the reason(s) for the ‘undulating’ response that I had shown previously. I don’t want to use the term ‘oscillating’ here! I am sure that it is not a circuit response; i.e., the transformer.
Thanks again for your advice.
Regards,
Charles.
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Chirp can be a little temperamental but I think it’s due to the transformer being reactive. If you haven’t loaded it down with a standard resistive load I would do that (though it sounds like you have).
Either way, I’d strongly recommend turning off the chirp just as a validation and doing a standard frequency step test here. Do the Chirp test and Snapshot it as a reference, then simply uncheck the “Use Chirp” checkbox and maybe use 3-4 steps per octave. When you step you don’t need a longer fft so you can use 32K to speed things up. If it hugs your chirp line at least you have some validation.
Also, if you haven’t tried this, you might try using a small buffer amplifier before the transformer. At low frequencies the transformer may take more current and the QA40x has a moderate output impedance. Using one won’t impact the test at all.
Thanks again, Mark.
Here is my cct:
Using the Freq Step, rather than the Exp Swp (and noting that it starts here at 5 Hz):
This is consistent with my previous plots, but better-looking.
As an aside, I am hoping to extend the LF response of this transformer down to below 3 Hz for a particular application by using an Op Amp on the transformer secondary, connected as a virtual earth. (For this application, higher frequencies above 4 or 5 kHz are of little interest.)
By the way, I like the way the Qa40x Plot app. makes it very easy to scale the plots!
Cheers, and thanks,
Charles.
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That looks great. Two hints if you want to be expert…
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Try Snapshot. Check here for a quick video but you’ll really like it if you’re adjusting stuff. Snapshots · MZachmann/QA40xPlot Wiki
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If you use dBR for the plot units (the upper right selector on-screen currently set to dBV) then multiple graphs will overlay at the exact same spot making comparison easy. It also shows bandwidth points trivially.
Enjoy.
Hi Mark,
Following your advice indeed makes the plot comparisons easier!
Here is the plot with my virtual earth load design on the transformer:
Not even 1 dB down at 3 Hz! (And -3dB at 3.5 kHz.) Not bad for a little transformer that fits within a 1 inch cube. Mission accomplished.
Thanks again and regards,
Charles.
1 Like