Making my headphones wireless

Discussion in 'The Projects Forum' started by dsw2008, Dec 8, 2007.

  1. dsw2008

    Thread Starter New Member

    Dec 8, 2007
    3
    0
    I'm looking to run the audio from my metal detector into my computer (wirelessly). The metal detector uses standard headphones.

    I have a 900 mhz wireless video/audio transmitter & receiver. Today I purchased a headphone jack & some audio rca cable. I ran the jack & cable from the metal detector into the audio of the wireless transmitter. Unfortunately there is no sound on the receiving end and I don't know why.

    Is the audio signal coming out of the metal detector different than the audio signal coming out of the headphones into it's speakers? Meaning - Do headphones convert the signals at all?

    Thanks,

    James
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    No, but the headphones are a lot different load. Headphones are going to be somewhere between 8 and 32 ohms, while an audio input will be something more like 50,000 ohms.

    What this means is that the signal level into your transmitter may be way, way more than it can handle. That may be the case even with the volume turned all the way down. You might try a bit more with the volume out of the detector turned down to just barely above zero, but the receiver may still get too much signal.

    If you're comfortable doing this, open up the metal detector amp and put a 20 - 47K resistor in series with the output jack and its source. It's pretty crude, but may drop your signal down enough to keep from overloading the transmitter input.
     
  3. dsw2008

    Thread Starter New Member

    Dec 8, 2007
    3
    0
    Thanks.

    I'm going to try this today. I called the dealer and the spec sheet said "high impedence" and the guy said 1000 ohms but he may be guessing.
     
  4. nitouken

    New Member

    Dec 17, 2007
    4
    0
    You could also put together a custom cable, with the resistors in the ends... a little more elegant, and less risk to the metal detector.
     
  5. dsw2008

    Thread Starter New Member

    Dec 8, 2007
    3
    0
    Just bought 3 packs of 1k, 4.7k, 10k resistors. I'll do all hacking on the plug and stay out of the metal detector. Hope I don't fry anything.
     
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