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Posts posted by walid

  1. any modern telephone has 4 diodes at its input i knowthat these diodes are for polarity protection but voice signals into or out of telephone are pass through these diodes how these signals are affected  are they rectified, i know that they are not rectified  are they carried over a DC level that enable them to fully pass, please i need an explenation about this point, thanks.

  2. hi audioguru thank you very much for the useful informations u gave me and i have another questions as:
    1- datasheets of hm9102
    2- when someone talk near MIC, i think that voice signal  go through C7 to base Q4 then through the power line to the collector of Q2  at this point i cant understand, is Q2 is a common base amplifier or something else ..... what if Q2 is NPN type
    3- i read that voltage between tip and ring lines is 48VDC, why they are 8.3 VDC at point A in the schematic.
    4-is Q2 function as a pass transistor regulator inaddition to its function as a control device 

  3. hi friends my name is walid from Gaza strip, first of all I am new in this great website and 50% in English language and love passionately electronics. I am interesting in circuit design analysis than build it i think that if u understand u assurance can build so i want to understand the circuit diagram of AK-700 telephone from:
    especially Q2, Q3 and related components i want a detailed discussion about each element in the circuit, i go to many many websites for help and back to some textbooks and asking some people but no results.
    Please someone help me, thanks.


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