[Coco] New circuit video coco2

[Zippster]

Hi Luis,

Though there are some simple transistor driver circuits out there,
they seem to only drive some composite inputs.

Implementation of the MC6847/MC1372 pairing varies by CoCo model.

Those with the 1372 in the RF box have an oscillator frequency tuning circuit
connected to the RF tank inputs, where a DC offset voltage is needed to generate
baseband composite.  This would be all CoCo2’s.

CoCo1’s do generate baseband composite from the 1372 before it is sent to
the RF box, but there is a transistor amp circuit in-between.  The signal could be
tapped here and levels adjusted with a simple driver circuit.

The boards I put together connect directly to the MC6847 and generate proper baseband
composite, along with handling sound, and put it into one convenient output jack.
They are based on Tandy’s own composite output solution, found on educational model
CoCo2’s.

Like anything with electronics, there are several ways to a similar destination, this is one way.  :)

- Ed


> On Mar 11, 2015, at 9:12 AM, Luis Fernández <luis46coco at hotmail.com> wrote:
> 
> The new circuit for composite video coco2, is necessary?
> Although not know much about electronics, I see using MC1372, let it also brings RF internally box
> And I wonder which prevents use circuits and are used to coco1 and frameworks are in cocopedia and elsewhere
> These schemes use only 2 singles transistors and other circuit there is something more complicated, but never as complex as this
> 
> Besides being magnificent and very Cadre, and is much appreciated the effort.
> but I imagine using a small plate or nearly directly, and would see the signal composed of video.
> --------------------------------------------------------------------------------- 
> Making  CoCoDskUtil V 1.X.X, Scan magazines and organize maltedmedia
> http://cococoding.com/cocodskutil/ Thank Aaron Wolfe
> http://www.tandycoco.com Thank Brian Blake
> My personal blog: http://www.luis45ccs.blogspot.com, 
> Excuse my English, I use google translator, my language is Spanish, I'm Spanish but I live in Venezuela
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