Re: black 'n white into white 'n black

On 19 Dec 2005 05:00:31 -0800, in sci.electronics.design "Cumin' Up"
<anani_6@xxxxxxxxxxx> wrote:

>I am New in electronic and I would to design a circuit that will
>inevert a white paper with black letters into a black paper with white
>letters. With my little knowledge that I get from from electronic
>within my three years in the field of Electronic, I think if I use a
>Camera circuit and modify it with a Class A amplifier i can be able to
>get it, bt I am still struggling to get there. Can somebody help me or
>give me a better idea on how to go on with my project, because this
>project will help people with eyes promblems who cant see black in
>white. Pls Help me my colleagues in the field of electronic

first you need to seperate the video syncs from the video picture

http://www.national.com/search/search.cgi/main?keywords=lm1881

see figure 3 in the data ***. The video is now referenced to ground.
Then use an inverting amplifier, gain of -1, this will turn black to
white .You need a bandwidth of at least 5MHz, Then you can resistively
mix the syncs from the LM1881 with the inverted video to feed the TV


martin
.