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Mark Dwight 6th September 2012 03:33 AM

ARTA help please (voltage probe)
My dyslexia and inability to read schematics is getting the best of me here. Could someone please explain this “voltage probe” thingy please. I’m not understanding how to make it and the point-by-point connections of it (where does it start and where does it end?) I know for most of you this is simple child's play but I’m having a mental block here Thanks.

Bibliophile 6th September 2012 04:43 AM

The Voltage probe refers to the circuit in Fig.1.3.
It is an attenuator/limiter to provide the correct input level for the soundcard and protect it from overload. Does the manual suggest values for these components? If not, you will have to measure the voltage at the speaker terminal with a suitable meter, look up the nominal input voltage for the sound card and, using those two values, calculate the resistor values for a voltage divider to give you that ratio.
It's a little more complicated because the input impedance of the sound card is effectively in parallel with the lower resistor so it has to be taken into account.

Bibliophile 6th September 2012 05:21 AM

OK, now I have had a look at the manual and it's explained directly beneath the diagram. You must have an earlier version as the Fig numbers are different. I suggest you download the latest version as it seems to be better documented.

Mark Dwight 7th September 2012 10:28 PM

Hmmm...turns out I did have an old version. But I’m still having trouble understanding how to connect R2. I do not yet understand schematics or electrical diagrams (but I’m learning.) So, for us novice types understanding why one point of R2 is shown not connected to anything is confusing. I’ve been told that part is connected to ground....but without seeing a physical layout I guess I’ll just never understand it.

Bibliophile 10th September 2012 10:36 PM

Sorry to be so long getting back. For some reason, I did not get notified that a reply had been posted.
The first diagram shows only one connection to the speaker whereas, in fact, there are two. The second connection is usually ground (except in bridged setup but let's not go there yet). Likewise, the soundcard input has signal and ground connections. So all should be connected togther as shown in the second diagram.

Mark Dwight 12th September 2012 01:51 AM

Thank you for your help. I think I understand it now. Also, this past week I've been learning everything I could about basic electricity/electronics. I have REALLY learned a lot and now understand the basics like voltage dividers. Youtube has some great lesson vids on these subjects and I've learned a ton from watching them. Now I'm hooked and reading everything I can find on the subject. Wish I'd learned this stuff in school. I just purchased two books on the basics of circuit design and plan to learn everything I can on the subject.
Thanks again.

Bibliophile 13th September 2012 10:31 PM

I wish you success in your journey.

kees52 29th September 2012 12:59 PM

Do I always need a mic preamplifier? connected to line in of video card, can arta also measure with a mic connected on videocard mic in.

I get so strange behavior with arta, or is there a software who can use mic in of video card.


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