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Reverse Color Organ

Discussion in 'General Electronics Discussion' started by Jon Jerpbak, Jul 24, 2015.

  1. Jon Jerpbak

    Jon Jerpbak

    3
    0
    Jul 24, 2015
    Using a light organ (Velleman MK114), I want a light to turn off to the music rather than turning on. This means the normal state of the light is on. I've tried using a NOT gate but the voltage coming out of the color organ is quite varied and the NOT gate is just on/off. I do not have access to an oscilloscope.
    I'm looking for a device or circuit that will adjust the output voltage depending on the input voltage.
    As an example:
    Assume that the color organ out put voltage is anywhere between 0v and 9v.
    If the input of this 'new' circuit is 0v, i want the output to be 9v.
    If the input is 3v, i want the output to be 6v.
    if the input is 9v, i want the output to be 0v.
    I just need to be pointed in the right direction.
    Thanks
     
  2. AnalogKid

    AnalogKid

    2,307
    649
    Jun 10, 2015
    Please post the Velleman schematic. In the mean time, it sounds like you are asking about an analog inverter. Not the same as a digital not gate because in your case there is no implied reference to invert things about. An inverting opamp with an offset of Vcc/2 or 4.5 V will do what you describe. Whether or not it will work in your application is a different thing.

    aka
     
  3. Jon Jerpbak

    Jon Jerpbak

    3
    0
    Jul 24, 2015
    Thanks for your answer, I'll start looking into your suggestions. I have attached the schematic
     

    Attached Files:

  4. Colin Mitchell

    Colin Mitchell

    1,418
    314
    Aug 31, 2014
    Remove R2. Connect Pin4 of the opto coupler to the base of T1.
     
  5. Alec_t

    Alec_t

    2,705
    717
    Jul 7, 2015
    ....and disconnect pin 4 of the opto coupler from ground.
     
  6. Jon Jerpbak

    Jon Jerpbak

    3
    0
    Jul 24, 2015
    That did the trick, working great.....thanks !!
     
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