[Coco] CoCo2 Composite Boards (update)

[Zippster]

Hi Gene,

These are small PCBs that replace the RF modulator can on CoCo2’s to provide
a composite output (with sound).  Uses a 2 conductor mini-jack (with ground of course),
and doesn’t require any case modification on the CoCo.

Does require removing the RF box on the motherboard (pretty easy with a temp controlled iron).
Based on the CoCo2 educational model’s factory composite board, which I RE’d.

Schematic here —>  <REDRAWN Schematicsch.jpg <https://7013705b-a-62cb3a1a-s-sites.googlegroups.com/site/thezippsterzone/coco2-composite-board-2/schematic-and-circuit-commentary/REDRAWN%20Schematicsch.jpg?attachauth=ANoY7cqtYsQJf0Y6moe0E4BRyl9T-t9_N3YMiYTLr1aWdX63Wu8rANRqWvXwrSHV6RrgmyEVWzA6Dt_k4SM5MDF_bfsOxVqz2_jPZFaAiUS_XRArPvod7RjyY57MdcuIvRS5lTuEciAUqCiEoVeklAthAg5zH5p8ZgXifUb2x6rP5rf8AENII2GRnlSbKSetCQAMbTfGvD1uk-LQKtSnGOsri68GNexjw_fRDHj9O7vq0junWm6CyVKkWQ2OQRP_gtzhrrSNq5hYtAWLbDapxBt1Vf7xvR44DK83So8mQRIGUS0WGPC7xlCuhdDe_KDfTvo0rykMGdSd&attredirects=0>>

It taps DC and AC current from the mb, running the AC through a voltage doubler to operate
a 12v regulator.  A 5v regulator runs the 1372.

The channel selection switch grounds the clock signal instead of sending it to the
1372 for B&W output, very clear for text only.

Pics of the two board types installed here, as well as a quick pic of the B-board output
on a ~60” LCD television.

<https://drive.google.com/folderview?id=0B1sgl615FlGnVVFhLTRtbVR4R2M&usp=sharing <https://drive.google.com/folderview?id=0B1sgl615FlGnVVFhLTRtbVR4R2M&usp=sharing>>


- Ed



.  
> On Feb 27, 2015, at 9:21 AM, Gene Heskett <gheskett at wdtv.com> wrote:
> 
> 
> 
> On Friday 27 February 2015 07:26:19 Steven Hirsch wrote:
>> On Thu, 26 Feb 2015, Zippster wrote:
>>> I’ll be placing orders for runs of these boards in the next few days, so
>>> I should have PCBs in a couple of weeks.  I’ll put some pics up somewhere
>>> (probably tomorrow).
>> 
>> I'm still interested, Ed.  Keep us posted!
>> 
>> --
> 
> And I am curious, and have to ask.  Does this design decode for /CS the same 
> as a real coco, with each valid for a $20 byte wide swath of I/O, or is it 
> taken another step finer so as to make an individual /CS only true-low for a 
> 4 byte wide space?  That would be an absolutely huge improvement.
> 
> And, can it use, by having the socket for the ribbon of a coco's keyboard, the 
> std coco keyboard?
> 
> Pix will probably help as the old Chinese proverb goes. ;-)
> This I assume is only level 1 capable?  eg no gime made out of unobtainium?
> 
> Cheers, Gene Heskett
> -- 
> "There are four boxes to be used in defense of liberty:
> soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
> 
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