NTSC signal color generation

Discussion in 'The Projects Forum' started by exoprime, Apr 24, 2013.

  1. exoprime

    Thread Starter New Member

    Apr 24, 2013
    1
    0
    Trying to apply color to a Black and white NTSC signal.

    I currently have extracted the burst timing, and composite sync timing through LM1881.

    Using HC4066, Bilateral Switch, I have produced the 3.579MHz oscillation on the colorburst timing.

    When I was trying to sum the clamped NTSC signal from video camera and the color burst oscillation from the HC4066 with LF356N, High Bandwidth Op-amp, it just would not sum both of the signals.

    I am using the LF356 as an inverting summer. Have tried various resistances as input 1k~100k ohms, however, the output was not visible....

    Does anyone know how to solve this issue?

    thanks
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    Without a schematic, I won't even speculate.
    Where are you getting the color information?
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,967
    744
    you cant make a black&white signal into a colour signal as there wont be any rgb information.
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,977
    3,221
    Where is the "color" coming from?
     
  5. DickCappels

    Moderator

    Aug 21, 2008
    2,647
    632
    That's pretty easy. The LF356 is down to unity open loop gain (or zero loop gain) at the color burst frequency. You need a very fast amplifier.

    Find an amplifier with an large open loop gain at 5 MHz. Those advertised as "video" amplifiers should work well. Even better, try making the circuit out of transistors. Transistor video amplifiers are all over the net.

    You can add color to a monochrome signal. Just sum the subcarrier with the luminance channel and adjust the phase relative to the burst for the hue you want and the amplitude relative to the luminance amplitude for the degree of saturation you want.
     
  6. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    OK, so he can have a picture that's red, or chartreuse, or whatever, instead of just shades of gray. I wonder why he would want to do that?
     
  7. WBahn

    Moderator

    Mar 31, 2012
    17,715
    4,788
    Sepia, perhaps?
     
    Ron H likes this.
Loading...