Amplified Music Circuit (Light Sensor) help

Discussion in 'Homework Help' started by renze, Jul 29, 2009.

  1. renze

    Thread Starter New Member

    Jul 29, 2009
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    I try fixing up this circuit but it don seem to work at all
    any 1 try help me find the error in the circuit please.

    [​IMG]
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    2,536
    What are you trying to do, and what are your results? Once a SCR is tripped it stays on, until the current going through it is stopped.
     
  3. renze

    Thread Starter New Member

    Jul 29, 2009
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    result: basically once it sence the light, music will start playing
     
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Do you have the specs of the music IC and the SCR?

    Greetings,
    Bertus
     
  5. renze

    Thread Starter New Member

    Jul 29, 2009
    6
    0
    Music IC: FT66T-12L
    SCR: C106MG

    Thks )
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    I can not find a datasheet for the music IC.
    I think there is to much voltage drop across the SCR for the music IC to work.
    Does the music IC function when connected directly to the battery?

    Greetings,
    Bertus
     
  7. renze

    Thread Starter New Member

    Jul 29, 2009
    6
    0
    im sorry, i see wrongly

    the music IC: BT66T-12L

    so i will need to add resistor for the music Ic to work ?

    yes the music Ic function once battery is connected
     
    Last edited: Jul 29, 2009
  8. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    For the safety of the music IC and the transistor put a resistor of 2K7 - 4K7 between the music IC output and the base of the transistor.

    As I understand the SCR does not swtich.
    The SCR you use is large for the application.
    The problem will be the holding current of the SCR.

    Greetings,
    Bertus
     
  9. renze

    Thread Starter New Member

    Jul 29, 2009
    6
    0
    so i will need to replace my current SCR? or is there ay method which i can use?
     
  10. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Look at its datasheet.
    You have the pins of the music IC connected backwards.
    The transistor needs to have a series base resistor as shown in the datasheet.
    The IC needs to have a supply bypass capacitor as shown in the datasheet.
     
  11. renze

    Thread Starter New Member

    Jul 29, 2009
    6
    0
    im lost now :'(
     
  12. Audioguru

    New Member

    Dec 20, 2007
    9,411
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    Here is what is wrong:
     
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