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Unknown Transformer----details required

Discussion in 'General Electronics Discussion' started by vinodquilon, Feb 12, 2010.

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  1. vinodquilon


    Jan 10, 2010
    I am planning to tap a telephone line (to feed DTMF decoder as shown in the attachment) through an isolation transformer 600Ω/600Ω of 1:1 type. In our local market it is not readily avail. After a lot of search I have found one Dax 56K DX-56PU modem contains one Transformer .

    Find the attachment T1 AASUPREME.
    For using that Transformer I have to know the following details.
    How can I know the following 4 specifications of the transformer,
    Impedance matching (intended value is 600 ohms to 600 ohms)
    Frequency response (intended value is 300-3400Hz for Plain Old Telephone System)
    Turns ratio (intended value is 1:1)
    Does it pass DC current through windings (otherwise I have to use separate capacitors at primary to block DC)

    Complete Transformer specification-
    aasupreme by
    C US 0514

    I cannot get the specifications through internet.

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    A lot of information seems to be available here.

    DC can pass through the individual windings of a transformer, but only an AC voltage on one winding will be coupled to the other winding.
  3. Resqueline


    Jul 31, 2009
    1: Impedance is a function of frequency. The transformer is just a mediator between the two sides' impedances, and only needs its own inductance to be high enough to make sure the lowest frequency is transferred w/o attenuation. Being used in a modem it's likely to be a 600 ohm tx.
    2: For sure it will cover that range, being used in a modem. Try it between an MP3 & a headset and listen to the sound quality.
    3: Measure the resistance of the windings. If they are fairly equal it's a 1:1 tx.
    4: ??? Of course a winding conduct DC. Of course separate windings are isolated does not transfer DC. Measure..
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