electrically routing a signal?

Discussion in 'The Projects Forum' started by icydash, Mar 9, 2011.

  1. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    Hey guys. I'm trying to create a circuit, an image of which (I know it's kind of crappy) is here:

    [​IMG]

    What I need help with are the circles called "switching circuits". What I'm trying to do is design a system where AC signal comes in (on the green path), and depending on what signal the Xbee receives and sends to the microcontroller, the microcontroller (using a control pin or whatever) either routes that AC signal into an A/D converter of the microcontroller (the black path) (the microcontroller will do some stuff and pop the signal out the other side), or it routes it around the microcontroller (a bypass) (the orange path).

    Basically, I'm just trying to make a microcontroller-controlled switch that routes a signal in two different directions.

    Any help would be greatly appreciated.
     
    Last edited: Mar 9, 2011
  2. Wendy

    Moderator

    Mar 24, 2008
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    What is the freq of the AC? A 4066 is a CMOS switch (digital mux actually) that can be used in analog mode.
     
  3. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    Hey, thanks for the reply. The AC is going to be guitar, so frequencies generally ranging from like 100Hz - 4kHz.

    Do you have a datasheet for that component? I'm looking at the http://www.national.com/ds/CD/CD4066BC.pdf right now, but it doesn't seem like you can switch between two paths with it; it seems to be more of an on/off thing...unless I'm reading it wrong, or using the wrong component.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Just a thought: Could you leave out the first (left-most) switch entirely? It would feed the guitar signal to both the micro and the output (right-most) switch all the time, but maybe the micro can just ignore it when the logic says to bypass. Then you just need for the output switch to toggle between straight versus processed signal.
     
  5. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    This is an interesting thought that would probably work.

    I was thinking of a relay possibly for the switch, though i'm afraid there may be a "click" or "pop" or whatever when it switches since it's electromechanical. Is this totally unfounded? -- I haven't worked with relays before.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    It could be a problem. If you wait for the signal to be at zero crossing and switch then it could be minimized.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    Probably not unfounded, given the high amplification of the signal. There are such things as solid state relays (SSR) but I haven't used one but I'm not sure that would make a difference.
     
  8. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    Well maybe the easiest answer then is to just have the signal go into the A/D pin of the microcontroller no matter what.

    Just have the microcontroller do nothing to the signal (send it right to the D/A and out the output to the guitar amp) when the circuit is in the OFF position. Conversely, in the ON position, have the microcontroller do its stuff (forward the signal to the Xbee over UART) before sending the data out the D/A.

    That'd work right....?

    [​IMG]

    Also, sidenote question: any ideas on a good microcontroller to use? the microcontroller isn't really going to do any processing, it's just going to either:
    (1) route the signal to a xbee chip (when the circuit is in the ON position), probably using UART (unless you guys recommend something better).... or
    (2) send the data out the D/A and to the output (a bypass basically when in the OFF position) to the guitar amp.


    So I don't need much -- whatever is cheapest and easiest to use with D/A and A/D conversions, UART and Xbees..
     
    Last edited: Mar 9, 2011
  9. shortbus

    AAC Fanatic!

    Sep 30, 2009
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  10. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    Cool thanks, i'll take a look at this in a few when I get back from work.
     
  11. icydash

    Thread Starter Active Member

    Jan 14, 2009
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    These look like exactly what I'm looking for, except the packaging is way small. Do you know of anything similar in DIP or that I can use to prototype on a breadboard? Or a way of prototyping with those maxium ICs?
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Did you see the link to all of their switches? http://para.maxim-ic.com/en/results.mvp?fam=swmux_low

    I didn't look at them because I don't know exactly what specs you need. I know they did have some that were in DIP style.

    Have you ever seen what they call a 'surf board'? http://www.solveering.com/products/products_adapters.html They have them a lot of places even on Ebay.
     
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