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Thread: FB to control audio switching?

  1. #41
    Variable Bitrate
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    Thanks Curiosity, after my last post, got curious myelf and did a bit of research and decided Q2 should have been a PNP transistor as per your revised diagram. I'll se if I can findone today.
    RodW
    2007 Toyota Hilux with a CarPC..

    Worklog: http://www.mp3car.com/vbulletin/work...ota-hilux.html
    OziExplorer GPS Embedded in RR: http://www.mp3car.com/vbulletin/sb-s...iexplorer.html

  2. #42
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    I gave up on the two transistor circuit and redid it all from scratch using just one transistor on the 12 volt line to reduce the voltage and fed it into the 4069 NOT gate.

    To make sure signal voltages input into the bilateral switch were the same, I fed the inverted output back into another NOT gate rather than use the enable line directly.

    Anyway, I finished soldering the board. With the 4069 in place, the switching logic feeds into the bilateral are correct. All I have to do now is to solder the RCA's on and try it out, but as it's 11:00 pm here, I thought I'd better call it a day.

    I will post some pics and an updated circuit diagram when I get a chance.
    RodW
    2007 Toyota Hilux with a CarPC..

    Worklog: http://www.mp3car.com/vbulletin/work...ota-hilux.html
    OziExplorer GPS Embedded in RR: http://www.mp3car.com/vbulletin/sb-s...iexplorer.html

  3. #43
    What can I say? I like serial. Curiosity's Avatar
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    Well, as long as it works. That's the point.

    I'm always using an NPN as a pull-down so I still don't know why that first one didn't work. I used pretty high resistance values, so it may not have been enough current to energize both transistors. PNP is just opposite. Grounding the gate enables it. As far as the bilateral switch, you just need the control voltage to go to 0 and as high as the supply and it should be fine.

  4. #44
    Constant Bitrate
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    Great work on this so far Rodweb,just have a question,i am planning on going back to a headunit for music so then i can use the comp.mostly for GPS, i am planning on using tallisman to redisign the gui and run ozi and igo and wmp for that matter straight from a tallisman shell there by solving the focus issues etc,etc of embedding in a front end,now to the question,do you think this unit will be fairly quick and reasonalbly quite to be able to switch h/u output off when computer speaks directions,i wonder if it would be possible to fade in and out?

  5. #45
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    Quote Originally Posted by millsy View Post
    Great work on this so far Rodweb,just have a question,i am planning on going back to a headunit for music so then i can use the comp.mostly for GPS, i am planning on using tallisman to redisign the gui and run ozi and igo and wmp for that matter straight from a tallisman shell there by solving the focus issues etc,etc of embedding in a front end,now to the question,do you think this unit will be fairly quick and reasonalbly quite to be able to switch h/u output off when computer speaks directions,i wonder if it would be possible to fade in and out?
    Millsy, the spec sheet on the chips shows that they both change state in 20 nano seconds so it would be pretty well instantanious.

    You don't need hardware to switch volume when the GPS speaks. I use Navimon Release: Navigon Voice Guidance Attenuation and it works a treat. It does not fully mute the music but attenuates the volume back to a level you set. I don't think it is specific to any front end, so it should work for you. Set the WAve volume to 100%, set IGO to volume of 80% or lower in that software and tell Navimon to cut in at 80% volume or less.

    To fade the volume in and out on the line level input would require a digital potentiometer added to the output and some logic to turn it up and down. As curiosity has said There are some neat chips that include multi channel mixing with audio controls inbuilt but they are very small form factors and thus probably beyond my soldering skills. You'd probably need to add a microprocessor or use the FB to control it all and write some on chip software to tie it all together and knowing your love of programming, you probably wouldn't want to stuff around with this...
    RodW
    2007 Toyota Hilux with a CarPC..

    Worklog: http://www.mp3car.com/vbulletin/work...ota-hilux.html
    OziExplorer GPS Embedded in RR: http://www.mp3car.com/vbulletin/sb-s...iexplorer.html

  6. #46
    Vendor - Qube colin's Avatar
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    Sounds like a USB soundcard to me... why program it all yourself.

  7. #47
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    Quote Originally Posted by colin View Post
    Sounds like a USB soundcard to me... why program it all yourself.
    Colin, The advantage of this approach is that the PC does not need to be on as would be the case if you used a USB soundcard. Also with the sound card, you would need to select the input from the Car PC somehow.

    If I can get this going, all I need is to turn the head unit on and I can listen to the radio. Turn the head unit off and I will be back listening to the PC if it is turned on.

    Having said that, I have got a good sound card picked out if I can't get this going. This will cost $20 and the sound card $200
    RodW
    2007 Toyota Hilux with a CarPC..

    Worklog: http://www.mp3car.com/vbulletin/work...ota-hilux.html
    OziExplorer GPS Embedded in RR: http://www.mp3car.com/vbulletin/sb-s...iexplorer.html

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