[sdiy] Video-synth DIY ?

[Grant Richter]

I met Dan Sandin, back in the day, he gave me the schematics for the IP.

I redesigned the Sandin image processor to use more modern chips. All  
of which are obsolete today.

Look at the LM1881 for your basic synch separator. This can take the  
place of a synch generator if you use an off-air tuner.

The hard part is to get a NTSC to RGB decoder and a RGB to NTSC encoder.

The video signals themselves are "back porch" clamped for DC  
coupling. You don't clamp to the front porch because of the color burst.
The back porch and front porch are the blanking intervals immediately  
before and after the horizontal synch pulse.
It doesn't help that each part of the video waveform has a cute name  
that you are assumed to already know.

Processing modules are crossfaders, high pass filters (edge  
extraction), comparators, exor gates, quantizers and things like that.
Pretty simple except for the 4-10 MHz band width and 75 ohm inputs  
and outputs. The 75 ohm I/O is nice but not absolutely required.

That can be handled with "WTA" or "wideband transconductance  
amplifiers" as made by Maxim and others.

There was a video module designed for the Wiard 300 system, but parts  
are all obsolete now.

Also the market place is maybe 20 people globally.

On Jun 28, 2005, at 1:37 PM, Metzger, Michael A wrote:

> Wow - look at all the responses. Contrast this with my similar  
> inquiry a couple
> years ago. I either got one reply or none, can't remember!
>
> So, CJ Metrophage, you're not going to believe this but.....I have the
> schematics and assembly instructions for the Sandin Image  
> Processor. That's the
> good news. The bad news is that they are in storage and I probably  
> won't be able
> to get at them until September. Since it was designed a long time  
> ago all the
> parts are obsolete. But the circuits could, of course, be  
> redesigned using
> modern components. (fun with surface mount!) IIRC there's also a  
> note from Dan
> Sandin with the schematics that gives people the go-ahead to build  
> the modules
> for non-commercial use. I'll check that when I get the schematics.
>
> As for the circuits themselves, I don't remember details on the  
> Sandin IP
> modules. But they all feed into an analog color encoder. The  
> encoder outputs the
> PAL & NTSC signals. You could get an encoder and feed it various  
> signals. That's
> what was done in this magazine article
> http://www.audiovisualizers.com/library/store/TVFX The TEA2000 &  
> SAA1043 chips
> are no longer produced.  And when you analyze that circuit you'll  
> see its rather
> basic anyway. You could probably make something more interesting in  
> short order.
>
>
> Here are AD's color encoders. I think only the first 3 accept  
> analog input.
> http://www.analog.com/en/subCat/0,2879,765%5F798%5F0%5F%5F0%5F,00.html
> Or you could get one of the digital encoders and feed it
> random/rhythmic/whatever digital pulses.
>
> Mike
>
>