Conversion of 3 channel colour organ to 4 channel

Discussion in 'The Projects Forum' started by Max12345, Sep 19, 2013.

  1. Max12345

    Thread Starter Member

    Aug 27, 2013
    63
    0
    Hi all

    I am trying to convert a 3 channel colour organ into a 4 channel one. Please see the pic.
    All I want to do is to split the existing midrange channel into 2, without affecting the low and high channels. I have added in another channel.
    1. Could you please help with the RC values for this?
    2. On low and midrange1 channel, I will be driving 4 Red and 4 Green leds each (total of 20mA). On the midrange2 channel, 6 Blue leds (total of 40mA) and on the high channel, 8 White leds (total of 80mA). Do I need to change the base resistors of the transistors? If so, to what? The supply voltage is 12v.
    3. The audio input is "line level". Where do I find this? I would like to use the speaker outputs directlly. Do I need an attenuator circuit? Can you provide me with a schematic please?
    Thank you for any help I may receive.
    Max
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    There is always a low-pass filter (R12 and C6) and a high pass filter (C7 and R13 with R14).
    I made some comments on how to change the edges of the filters:

    [​IMG]

    Bertus
     
  3. Max12345

    Thread Starter Member

    Aug 27, 2013
    63
    0
    Hi Bertus
    Thanks for the response.
    Regarding the time, when I went into the CP, I discovered that the time was already set correctly. I am in Cape Town, South Africa so it is GMT +2.
    Should Mid1 be from 320Hz to 800 Hz, and mid2 from 800Hz to 2.4KHz?
    How do I determine the values of the caps to achieve this?
    Or should I just change Mid1's cap to 47nF and Mid2's cap to 10nF?
    Do you know of a site or program which will allow me to see the effect of changing the caps to specific values to see whether they fit into the freq response curves?
    Max
     
  4. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
  5. Max12345

    Thread Starter Member

    Aug 27, 2013
    63
    0
    Hi Bertus
    Thanks. I'll go and check out the links...
    Max
     
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