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1.5 Volt Tracking Transmitter

Discussion in 'Electronic Projects' started by ElectroMaster, Jul 24, 2002.

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  1. andrebc

    andrebc New Member

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    smart idea using the IC, but why did not you use a coupling capacitor before Q2?
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    He does, what do you think C3 is?.
     
    Last edited: Apr 24, 2009
  3. Roff

    Roff Well-Known Member

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    After reading Andrebc's posts, one wonders if he is looking at the same schematic we are.:rolleyes:
     
  4. dave

    Dave New Member

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  5. andrebc

    andrebc New Member

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    Chill out Mr smart! dont get bothered by other members questions, just ignore them if you cant respond.
     
    Last edited: Apr 25, 2009
  6. andrebc

    andrebc New Member

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    I believe C12 is a coupling capacitor, how come it's not the same value as C1 and C2. Is that because the audio frequency will be different after it passes the the first RC circuit?
     
  7. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    C12 is an RF coupling capacitor, and NOT an audio one.
     
  8. audioguru

    audioguru Well-Known Member Most Helpful Member

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    C1 and C3 are 330nF (330,000pF) and pass audio frequencies from 30Hz to 15kHz.
    C12 is 30pF and passes radio frequencies from 88MHz to 108MHz. The reactance of C12 at 100MHz is only 53 ohms so it passes the radio frequency very well.

    Q2 is the radio frequency oscillator and its output to C12 is near 100MHz.
     
    Last edited: Apr 25, 2009
  9. Sceadwian

    Sceadwian Banned

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    Spam alert
     
  10. Roff

    Roff Well-Known Member

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    I have been duly chastised.:rolleyes:
     
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