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Ruby amp debugging help

Discussion in 'General Electronics Discussion' started by electronoobz, Dec 22, 2012.

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  1. electronoobz

    electronoobz

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    Jan 14, 2012
    i installed the ic and the jfet correctly.. there's a hiss and buzzing noise when im touching pin 2,1,8..

    any clue?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Schematic?

    The most probably reason is that you're amplifying hum that your finger is inserting into the circuit.
     
  3. electronoobz

    electronoobz

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    Jan 14, 2012
    im doing it to check if it will have sounds but when im using the jack there's no sound amplified.. but again will sound if i touch the pin 2..

    when im touching 1 and 8 (which is the gain) there's a lot of buzzing noise which means it is really working.. just doing it for check

    [​IMG]
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Do you get the sound if you touch the gate of the jfet?

    What is the voltage across the 3k9 resistor?
     
  5. electronoobz

    electronoobz

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    Jan 14, 2012
    yes i hear a reaction when im touching the gate and source... any more clue??
     
  6. electronoobz

    electronoobz

    226
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    Jan 14, 2012
    i remember asking you if i could use 2n5458 you said yes.. i really think that is not the problem.. the ic is working also.. so very sad because of this...
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    OK, so you hear the buzz when touching the input, but not when the input source is attached.

    What is the input you're connecting it to?

    Have you tried a capacitor in series with the input?

    Is it possible you are using a mic that requires phantom power?
     
  8. electronoobz

    electronoobz

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    Jan 14, 2012
    im using my guitar.. cant hear any sound.

    my guitar electronics is fine.. i tested it in out power amp
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Have you tried a capacitor in series with the input?

    Are you connecting the ground?

    The idea is to answer ALL questions, not just the last one.
     
  10. electronoobz

    electronoobz

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    Jan 14, 2012
    yes i did... caps series with the input?? not yet.. what value anyway? 100uf?
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    0.1 uF to 1 uF should be fine for testing.
     
  12. electronoobz

    electronoobz

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    Jan 14, 2012
    ok thanks!!!
     
  13. electronoobz

    electronoobz

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    Jan 14, 2012
    So sad, bad luck today.. Bought wrong value

    Can I use 4.7uF?? Which side for positive??
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Yeah, sure. Connect -ve to the gate of the JFET
     
  15. electronoobz

    electronoobz

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    Jan 14, 2012
    bad news... not working still
     
  16. electronoobz

    electronoobz

    226
    0
    Jan 14, 2012
    i tested my ruby mp with my multitester.. (volt tester) and put the first one to ground and the other one to every part

    pin 2,3,4 has no voltage (3 and 4 is conencted to ground)
     
  17. Relayer

    Relayer

    39
    0
    Dec 15, 2012
    I hope you realize you're using an RF JFET, not suited for audio.
    Regards,
    Relayer :D
     
    Last edited: Dec 27, 2012
  18. davenn

    davenn Moderator

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    Sep 5, 2009
    Hmmm, yeah that thought crossed my mind too.
    The lowest freq's I have used them on have been between 200 - 500kHz
    for receiving aeronautical NDB beacons
    I'm not sure how they perform below that ... maybe no problem ??

    Dave
     
  19. electronoobz

    electronoobz

    226
    0
    Jan 14, 2012
    but i asked steve a long time ago about that.. i also told him that im making an amp.. he said 2n5458 is ok
     
  20. davenn

    davenn Moderator

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    Sep 5, 2009
    but are you using that one or the MPF102 as shown in the cct diag ??

    Dave
     
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