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telephone receiver wanted for audio recording

Discussion in 'Electronic Design' started by anthony altomare, Nov 3, 2005.

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  1. I have been wondering how to wire a telephone receiver's microphone for
    use with a sound board. I do some audio recording with friends and
    have wanted to convert a telephone for this purpose for sometime now,
    but just recently had the gumption to do the research. While scowering
    the net for possibly a how-to or some information, i've only found
    people making or selling wire-taps for recording both sides of a
    conversation. I also found information on the microphone; telephones
    use a crystal microphone. Will I be able to just slap an xlr end on
    that bad boy and record away or will i need to put an amp on it? so
    many questions! any thoughts?
     
  2. Phil Allison

    Phil Allison Guest

    "anthony altomare"

    ** Completely false.

    Telephones use a variety of mic capsules - but never "crystal".


    ** Depends on the particular phone but in most cases the answer is no.

    Telephones are " phantom powered " - like condenser mics are - but not
    the same way.

    Find someone technical to modify a phone handset and pick one that has a
    dynamic capsule.



    ........ Phil
     
  3. aaaltomare

    aaaltomare Guest

    I have a fair amount of technical knowledge (going back and reading my
    previous post it may not seem too aparent). I'm just looking for
    information that will point me in the right directions. knowing that
    telephones run on phantom power is a good start.

    I also started thinking about the telephone sets used on old hotel
    switchboards. They were just a handset with a quarter inch handset
    coming out of it. would those work the same way i would need to modify
    a regular phone handset?
     
  4. Don Bowey

    Don Bowey Guest


    Phones are not powered by a phantom circuit.

    In a phone circuit, normally a negative polarity is applied to the Ring wire
    and the current flows through the telephone to the Tip wire, to which the
    positive polarity of the power supply is connected. In a phantom circuit,
    current flows the same direction in both wires.

    If you are just trying to use a carbon microphone and "have a fair amount of
    technical knowledge," wire the microphone in series with a battery (6V will
    do), and a resistor (200 Ohms or so). Take the signal from across the
    microphone, or the resistor, via a blocking capacitor. There are more
    elaborate methods which are more efficient, but this will give you a good
    start.

    Carbon microphones tend to be noisy, and also the carbon granules tend to
    pack, reducing the conversion from sound pressure to electrical signals. A
    sharp rap against something solid helps improve the latter condition.

    Don
     
  5. Phil Allison

    Phil Allison Guest

    "Don Bowey"

    ** Of course they are - you dimwit.


    ** Phantom powering refers to any circuit where the power to operate the
    device is fed along the same wires used for signals to or from the device.

    Condenser mics used a 3 wire, balanced circuit with the DC phantom delivered
    in common mode.

    A mast head RF amplifier uses the coaxial feeder cable to supply it with AC
    or DC power from a remote supply.



    ** Better not overtax the OP - he is still trying to figure out what
    crystal mic is.



    ............ Phil
     
  6. Don Bowey

    Don Bowey Guest

    I seem to have overtaxed you. Sorry about that....

    Don
     
  7. Phil Allison

    Phil Allison Guest

    "Don Bowey"

    ** The only thing you are overtaxing is your cock.



    ......... Phil
     
  8. Ross Herbert

    Ross Herbert Guest

    This article http://www.siliconchip.com.au/cms/A_105109/article.html
    explains what you need to do to interface a standard analog telephone
    to your sound card. You simply require a transmitter power supply (9V
    battery) which is isolated from the sound card, (hence the
    transformer).
     
  9. Ross Herbert

    Ross Herbert Guest

    I have noticed when accessing the link via my post you don't see the
    full Silicon Chip article, unless you are prepared to pay to see the
    rest of it, that is. If you type 'voip phone adaptor silicon chip'
    into Google you will get the full article for free. At least, it does
    for me.
     
  10. Don Bowey

    Don Bowey Guest


    Do yourself a favor, and read more on the subject.

    Just so I can have a good laugh, please give me the best reference you can
    find to support your view that telephones are powered by a phantom circuit.
     
  11. Phil Allison

    Phil Allison Guest

    "Don Bowey"

    ** Try reading what was posted already:


    " Phantom powering refers to any circuit where the power to operate the
    device is fed along the same wires used for signals to or from the device.

    Condenser mics used a 3 wire, balanced circuit with the DC phantom delivered
    in common mode.

    A mast head RF amplifier uses the coaxial feeder cable to supply it with AC
    or DC power from a remote supply. "



    ** Do you laugh like a hyena or a jackass ?



    ** Does DC current pass down the signal wires to power the phone ?




    .......... Phil
     
  12. Ross Herbert

    Ross Herbert Guest

    Strictly speaking Phil, a POTS instrument is not phantom powered,
    although I can see why it would fit that description under your broad
    definition.

    If we go back to the earliest central battery telephone instruments
    you will recall that they used a carbon granule microphone. The idea
    is that the DC line current flows through the microphone which in turn
    varies its resistance proportionate to the sound pressure waves on the
    diaphragm thereby varying the line current. Thus, the microphone
    simply modulates the line current which is then passed through a
    transformer in the exchange line interface circuit to derive the AC
    speech signal for transmission over the network.

    While modern telephone instruments no longer use a carbon granule
    microphone (although telephones employing them will still work today),
    the IC in these instruments must duplicate exactly what the old carbon
    microphone did, ie. modulate the DC line current. The fact that the IC
    derives its minute operating power from the line voltage may qualify a
    modern telephone as being phantom powered under your broad definition,
    but this fact is secondary only to the operation of the telephone, and
    in my opinion doesn't truly fill the bill. Phantom powering devices in
    telephony always relied upon the use of centre-tapped signal
    transformers such as the venerable 4012A.
     
  13. Don Bowey

    Don Bowey Guest

    Your posts are not what I would ever call a "reference."
    That is complete nonsense. Provide a reference to support this.
    Yes, when done correctly, that is a phantom circuit.
    You are describing a simplex power arrangement.

    Yes, so what? That is not a phantom configuration.
    Look, jackass, if you can't find a good reference, just say so. I suspect
    that you are the type of person who increasingly raises the volume of his
    voice as replacement for a good argument.

    You aren't worth the effort to continue this. Post what you will, but I
    will not respond to you on this topic.
     
  14. Phil Allison

    Phil Allison Guest

    "Don Bowey"


    ** Piss off - you pathetic troll.




    .......... Phil
     
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