Use This audio detect circuit to drive a DPDT IC Switch

Discussion in 'The Projects Forum' started by mpatterson557, Sep 14, 2011.

  1. mpatterson557

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    Jul 3, 2010
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  2. R!f@@

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    And why are u telling us all this ?
     
  3. SgtWookie

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    Hmm, I think they're referring to this thread:
    http://forum.allaboutcircuits.com/showthread.php?t=58983

    After a quick look, the first circuit you posted:
    http://www.discovercircuits.com/DJ-Circuits/audiodetect1.htm
    seems like it'll work OK with your intended voltage range (you'd need 4 of them to control 3 stereo inputs), but none of the DPDT switches will, as they are limited to 5.5v absolute maximum input voltage.

    Using a linear regulator will result in inefficiency. Switching regulators will be somewhat complex and introduce noise. I don't know how you are planning on powering this project; "6V" could be either batteries or a mains-powered supply.
     
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  4. mpatterson557

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    Thanks for the input and advice.
    I had thought that it was simple to add a resistor to circuit to make up for voltage potential. I can source 3 volts, I have a battery pack that runs all this. just tap halfway through one of the packs.
    So lets leave that circuit at three volts, how do you switch the ADG888
    On a relay you would supply a hot like the VOX circuit, bear with me I am talking myself through this, but on the IC it looks like IN1 pulls the "relay contacts" down to the NO position. So do I connect the 3volt hot from the VOX circuit to the IN1? Should I add any components?
     
  5. SgtWookie

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    Hmm. Well, it's a bit more than that.

    Let's get some things straight.

    You're wanting to have three stereo inputs, correct?

    And you want the circuit to automatically select the input that is active that has the highest priority, right?

    I guess I haven't had enough coffee yet this morning...
     
  6. R!f@@

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    Care to join me.:D
     
  7. mpatterson557

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    Yes.... I would like to have three inputs eventually. Right now I only really care about two. I would like to understand how the circuit works that way I can apply the knowledge in other areas.... But back to reality, the logic statement would be something like this: Audio in on IN1 IC1 in NC position(IN1 to Out1) If audio signal present IN2 then switch IC1 to NO position (IN2 to Out1)
    Then second step: Take Audio Out link to IN3: audio in on IN3 IC2 in NC position(IN3 to Out2) if audio signal present on IN4 then switch IC2 to NO position (IN4 to Out2)

    So only user exposed ports would be IN1, IN2, IN4, Out2
    IN1===
    IC1=Out1=IN3===
    IN2=== IC2==Out2
    IN4=================

    so I think that would only mean two iterations of this circuit
     
  8. SgtWookie

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    I've started on a simulation for this project, but I keep getting interrupted and having to leave it for awhile - I've been busy yesterday and this morning, and have to take off again. Hope that I'll have some time to work on it later on today.
     
  9. mpatterson557

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    What is a simulation?
    I also bought Eagle 5.11... Hmmm... need to goto school to figure out the libraries.
     
  10. SgtWookie

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    I'm using LTSpice, which is a free PSPICE simulator program downloadable from Linear Technology's website. Google "LTSpice download" to get the address.

    LTSpice isn't the end-all be-all for circuit simulation, but it's quite good, and it's very free, and there are quite a few models available for it besides the defaults that are supplied with it. It's a little bit quirky to learn, but it's quite handy.

    Joining the Yahoo! LTSpice Users Group will get you access to lots of models and symbols for downloading, along with helpful people to ask questions of.

    SPICE simulations are quite useful to get an idea of how a circuit might perform before you start building it with actual components. As most models are approximations, the results won't be entirely accurate - however it serves as a very useful tool to find a good starting place for prototype models.

    I haven't forgotten you (it might seem like it); I've been quite busy the last few days.
     
  11. mpatterson557

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    Jul 3, 2010
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    where in the spice library do you find a lmc7215, I found a spice file mod but no symbol so which symbol file should i use, or is there a equal to the lmc7215
     
  12. SgtWookie

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    Gosh, I've done it again; dropped the ball. So many problems, so little time....

    Did you download LTSpice, or are you drawing it up using Cadsoft's Eagle still?

    I downloaded a library of opamps and comparators from National's website and saved them in my:

    \Program Files\LTC\SwCadIII\lib\sub (your directory structure may be different)
    directory as nat_semi.lib - then I copied the opamp2.asy symbol file and saved it with two different names:
    NATL_SEMIAMPS.asy and
    NATL_SEMIAMPS2.asy
    and saved them into:
    \Program Files\LTC\SwCadIII\lib\sym\Opamps
    They're almost the same, but the 1st one has the inverting input on top, the 2nd has the noninverting input on top.

    I'm attaching a couple of .zip files:
    Opampssub.zip
    Opampssym.zip
    I threw in some OnSemi and TI stuff as well. There are also comparators in the files; some will bomb out because of pin mismatches. I haven't gone through all of them.

    After you've extracted the files to where they go, start up LTSpice, start a new schematic, and click on the Component icon (the AND gate) on the menu bar.
    Look in the Opamps directory for "NATL_SEMIAMPS" and "NATL_SEMIAMPS2". Drop one of each into the schematic, just so you can see the difference.

    The following procedure is kind of unique to these libraries; I don't recall how I learned about doing this - but it's a way I found out to put a bunch of parts in one file, and just use a couple of symbols to select them with.

    Next, right-click in the middle of one of the opamps. You should see a menu open up.

    On the "SpiceModel" row, you'll see "NATL_SEMIAMPS" - triple-left-click on it, and it should turn into a scrollable list.

    Scroll way on down through that list (wow, there's a lot in there!) until you get to "LMC7215/NS", and click on it. The selection list should minimize, but you'll still see the arrow on the right side of the bar.

    Then, left-clicking OK once will make a sound and the bar will disappear so that you know LTSpice has accepted your selection; clicking OK once again will close the menu.

    If you don't select an opamp from the list, you won't get an output.
     
  13. SgtWookie

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    Anyway, here's the simulation I started on.
    See the attached.
     
  14. mpatterson557

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    Jul 3, 2010
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    learning to use lt spice, got the opamp working but now where do you find the modal/symbol for the zetek, i found several (54) spice modals on their site but none available for the zxmd63N02x/ztx. found a zetek.lib file, but i thought that the lib file contained the sim instructions for the components and the asy file is the symbol that you look at and serves as the interface between user drawing and component functions?
     
  15. SgtWookie

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    I guess I'll send you the Zetex.lib that I have. Give me a bit.

    I spent a fair amount of time working on the sim yesterday evening, but seem to have
    run into a snag.

    They didn't have a model for the ADG888, but they did have one for the ADG884. It's useable for this, as it has a pair of SPDT switches with two drivers; if the driver inputs are tied together it effectively becomes a single DPDT switch; the ADG888 consists of two DPDT switches. I created a symbol for it, and added it in - but something either isn't quite right with the model, or it's not compatible with LTSpice.
     
  16. SgtWookie

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    Haven't forgotten you, but I still haven't figured out what's wrong with the ADG884 model. :rolleyes:
     
  17. mpatterson557

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    Jul 3, 2010
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    I thank you for all the time you are spending on this. I really appreciate your willingness to help out.
     
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