Audio Switching Device Project...Need Ideas and Input...

Discussion in 'The Projects Forum' started by sandiegojoe, Feb 26, 2010.

  1. sandiegojoe

    Thread Starter New Member

    Feb 26, 2010
    4
    0
    Hello Everyone,
    This is my first post here…Thanks for letting me to join your forum…

    I have an idea for an electronic audio project that I would like to build. It’s kind of a specialized device that doesn’t seem to be available commercially, so I would like to design and build it myself, just for fun, and I’m asking for some help with the circuits etc because I don’t know much about that.

    Current I have an existing device where the primary purpose is use a set of headphones to listen for a periodic audio tone...But that can get rather boring...So my idea is to create an audio switching device so I can listen to my Ipod through the same headphones while I wait for the periodic tone...

    Basically, I envision a small box big enough to house a “AA” or “AAA” battery power supply that will have 2 Input jacks on one end and 1 Output jack on the other end.

    Input 1 will be a 1/8 jack for an Ipod which will continuously play music…Input 2 will be a ¼ jack that will periodically produce an audio tone…Output 1 will be a ¼ headphone jack…

    The basic operation will be, the Ipod ONLY will play music continuously into Input 1, through the box, and into the headphones at Output 1…When an audio tone of sufficient strength is heard through Input 2, the music from Input 1 will be cut off for a number of seconds, and then ONLY the audio tone from Input 2 will be heard through the headphones…A predetermined amount of time passes after Input 2 goes silent, then the device will switch back to Input 1, and ONLY the music will be heard again…

    I would like the device to have a control to adjust the signal strength of Input 2 required to trigger the switch between Inputs 1 & 2…A control to adjust the amount of time Input 1 will remain silent (1 to 10 seconds)…A volume control for Output 1 to the headphones…And an on-off switch (could be included with any of the other controls)…

    When the device is turned ON I would like it to operate as described above…When the device is turned OFF I would like the periodic tone from Input 2 to be heard through the headphones…

    I would like to build a larger sized prototype at first to proof the design, and then later make another usable model reducing the size as much as possible…

    If anyone has any advice, ideas, or comments about how to start this project, I would enjoy hearing them…And if anyone knows of any existing plans or circuits that are similar to this idea I would enjoy seeing them…

    Thanks Everyone,
    SanDiegoJoe
     
  2. sandiegojoe

    Thread Starter New Member

    Feb 26, 2010
    4
    0
    Maybe I need to give a little more information about what this device is and how it will be used.

    I'm an avid metal detectorist (that's right...one of those guys you see at the beach) and I've been doing it for years...I wear a large set of headphones and walk around swinging my machine waiting for it to "Beep" and tell me when to dig...Sometimes 10 or 15 minutes will go by between beeps...I think it would be cool to listen to music in the mean time, but I don't want to miss any "Beeps"...So my idea is to make a device that goes between my machine and my headphones...I would also plug in the Ipod and listen to music through my headphones...When the metal detector beeps, the Ipod would go silent, and I hear only the beeps...Once the detector stops beeping, a few seconds delay will pass and the Ipod comes back on...

    Not sure if this is even possible but thought I would run it up the flagpole and see if anyone has any ideas how to make this work...

    Here is a basic diagram/flowchart that I have so far...
    Thanks,
    SanDiegoJoe
     
  3. sandiegojoe

    Thread Starter New Member

    Feb 26, 2010
    4
    0
    Someone from another forum suggested trying a VOX or Ducking Circuit...

    I did find a few Voice and/or Tone activated plans but I need to find a way to incorporate the delay into those circuits...

    The ducking circuit is an interesting idea...Never heard of that before...Very much like what I'm looking for...So far I can only find some heavy duty DJ stuff...But it is quite adjustable with delay, volume, etc and I like that...It would be good to find something more portable or light weight...

    If anyone knows where I can find some plans for a Ducking Circuit please let me know...I think that's the way I'm going to go if I can...

    Thanks,
    SanDiegoJoe
     
  4. gizmoman0

    New Member

    Jan 21, 2010
    26
    1
    hm I'm a bit rusty but I'm sure you could put together a level detector circuit which listens to your metal detector line and triggers a 555 timer set up as a one shot or monostable multivibrator to control the switching mechanism and also determine how long to pass the tone. Maybe thats too complicated unless someone wants to expand a little
     
  5. daviddeakin

    Active Member

    Aug 6, 2009
    207
    27
    It sounds like all you need is a simple 2-channel mixer. A dual op-amp could do that, although it needs to be able to drive your headphones so you'll probably need a couple of 9V batteries rather than AAs (a slightly beefy opamp like an OP275 can do it). Just google "opamp mixer" and you will be inundated with circuits and explanations along the lines of:
    http://www.musicfromouterspace.com/analogsynth/oddsandends.html#SIMPLEAUDIOMIXER

    Just adjust the inputs/volume so you can hear the tone above the music, or are you very worried about missing the tone?
     
  6. sandiegojoe

    Thread Starter New Member

    Feb 26, 2010
    4
    0
    Thanks for the replies...

    Yes...I am very concerned about missing the tone...I could simply get a 2 into 1 accessory and plug the detector and Ipod into the headphones and adjust the volumes accordingly...But it is very important that I hear the detector signal as it occurs and also be able to hear it in detail...The detector doesn't just beep...It has variable tone and variable volume...It actually "talks" and tells me a number of things like what type of metal, how deep, how large, etc...So I need the music to completely mute so I can "listen" to the signal...And I need this to happen automatically because my hands are usually full and sometimes covered with sand and/or salt water...

    Here's something I ran across in my searchings...It's a PA system "Ducking Module"...It's small a little bigger than a business card and maybe 1/4 inch thick...This company has several versions of this device for different applications, with different delays, fades, mutings, and adjustments...They all run on a separate 24 - 33vdc @ 35ma power adapter...

    http://www.performanceaudio.com/media/pdf/171/3043_s.pdf

    Would it be possible to put that in a small box, wire it with the various Ipod & Detector & headphone jacks, and use a few 9 volt batteries hooked to an on-off switch?...Might be a quick fix to what seems to be a complicated gadget?...

    Thanks again,
    SanDiegoJoe
     
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