[Coco] New circuit video coco2

[Joe Grubbs]

And Ed, didn't you also notice that the circuit you're using (Tandy) was better than the application circuit in the 6847 datasheet?


> From: zippster278 at gmail.com
> Date: Wed, 11 Mar 2015 12:12:10 -0500
> To: coco at maltedmedia.com
> Subject: Re: [Coco] New circuit video coco2
> 
> 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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