[Coco] COOL Look what I found! (VideoMod for CoCo2)

Fri Jan 9 07:51:52 EST 2009

Hi George,
Thanks for sharing that document. I will try that composite circuit and 
see how it works. It looks like the same circuit I built back in the mid 
80's on a CoCo 2.

Alan Jones

-- 
N8WQ - Canal Winchester, Ohio
http://exwn8jef.googlepages.com/home
http://n8wq.blogspot.com

George Ramsower wrote:
> http://sunpal7.mit.edu/6.111/mc6847/6847.pdf
> Here is the data sheet on the 6847. On the bottom of pp. 12 there is a 
> sample ckt for connecting the MC1372 to a composite monitor. It only 
> uses two transistors
> It's been many years since I connected a coco to a TV bypassing the RF 
> circuitry. I'm pretty certain pin 12 was where I picked up the video. 
> From there, I think I had one transistor to invert the signal and then 
> injected in the video detection point on the B&W TV set. I do remember 
> seeing pixels for the first time. The image was perfectly sharp.
>
> George
> ----- Original Message ----- From: "N8WQ" <exwn8jef at gmail.com>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Thursday, January 08, 2009 12:27 PM
> Subject: Re: [Coco] *COOL* Look what I found! (VideoMod for CoCo2)
>
>
>> Hi Fedor,
>> Your board is clearly a "through hole" project.
>> I can see the 4 transistors, variable cap and potentiometer on the 
>> circuit board.
>> That looks like a nice project for the CoCo.
>>
>> Alan Jones
>>
>> -- 
>> N8WQ - Canal Winchester, Ohio
>> http://exwn8jef.googlepages.com/home
>> http://n8wq.blogspot.com
>>
>>
>>
>> Fedor Steeman wrote:
>>> Hi all,
>>> Well, there is definitely a little board to be added, but I do not 
>>> know the
>>> technical jargon for this technique. Of the modified CoCo2 I possess 
>>> that
>>> has this videomod, I added a range of pictures to my gallery on
>>> coco3.comfor the interested to peek at:
>>>
>>> http://coco3.com/modules.php?name=Gallery&g2_itemId=1483
>>> <http://coco3.com/modules.php?name=Gallery&g2_itemId=1483>
>>>
>>> Cheers,
>>> Fedor
>>>
>>> PS: Nobody interested in the SCART connector? :-(
>>>
>>> 2009/1/8 N8WQ <exwn8jef at gmail.com>
>>>
>>>
>>>> Hi George,
>>>> The last time I looked the Color Computer (1, 2, or 3) didn't have any
>>>> surface mount components. LOL
>>>> The circuit has 22 parts, which includes one variable capacitor and 
>>>> one
>>>> potentiometer.
>>>> If you look on page one you can read "SMD technick."
>>>> He clearly shows the circuit raised on top of the rf video modulator.
>>>>
>>>> Alan Jones
>>>>
>>>> -- 
>>>> N8WQ - Canal Winchester, Ohio
>>>> http://exwn8jef.googlepages.com/home
>>>> http://n8wq.blogspot.com
>>>>
>>>>
>>>>
>>>> George Ramsower wrote:
>>>>
>>>>
>>>>> ----- Original Message ----- From: "N8WQ"
>>>>>
>>>>>  Hi Fedor,
>>>>>
>>>>>> That looks like a SMT (surface mount) component layout. A SMT pc 
>>>>>> board
>>>>>> would have to be made or you could use what us home brewer's call 
>>>>>> "manhattan
>>>>>> style" construction. Or we could translate the project to 
>>>>>> "through hole"
>>>>>> components. It would be nice to see the schematic though. LOL
>>>>>> The BSR14 is a NPN general purpose amplifier.
>>>>>>
>>>>>> Alan Jones
>>>>>>
>>>>>>
>>>>> He's showing where on the RF modulator to make connections. The 
>>>>> ckt he
>>>>> built only has about three or four parts on it.
>>>>> Usually this mod only require a transistor to invert and amplify 
>>>>> the video
>>>>> that goes into the modulator.
>>>>> Although I can't read what he's said, it looks to me to be an 
>>>>> installation
>>>>> guide for the little ckt. This is probably why there's no 
>>>>> schematic of the
>>>>> actual ckt.
>>>>>
>>>>> George
>>>>>
>>>>>
>>>>>>
>>>>>> Fedor Steeman wrote:
>>>>>>
>>>>>>
>>>>>>> Hi all,
>>>>>>>
>>>>>>> While going through the huge lot of copied CoCo Manuals I 
>>>>>>> inherited from
>>>>>>> Michel Collette, a former Dutch CoCo-society regional 
>>>>>>> coordinator, I
>>>>>>> discovered the following schematics for making a video buffer 
>>>>>>> mod for
>>>>>>> the CoCo2, enabling a CoCo2 to be coupled up any television or 
>>>>>>> video
>>>>>>> equipment with a composite video input:
>>>>>>>
>>>>>>> http://www.steeman.dk/CoCoManuals/VideoMod_(KoenVaartjes).pdf
>>>>>>>
>>>>>>> How cool is that!?
>>>>>>>
>>>>>>> It is all in Dutch, written by someone called Koen Vaartjes, but if
>>>>>>> people
>>>>>>> are interested I could translate, clean it up, perhaps redo the
>>>>>>> schematics
>>>>>>> in a graphics editor and put it up on a webpage!
>>>>>>>
>>>>>>> Some of the equipment i inherited from Michel Collette actually 
>>>>>>> included
>>>>>>> a
>>>>>>> CoCo2 with this video mod. I tried it out when I first 
>>>>>>> discovered it and
>>>>>>> it
>>>>>>> worked flawlessly then. After having transported the CoCo one time,
>>>>>>> however,
>>>>>>> something went wrong, because after that all I got was a black 
>>>>>>> screen
>>>>>>> and no
>>>>>>> sound. I believe there must be a loose contact somewhere, 
>>>>>>> because every
>>>>>>> now
>>>>>>> and then when I try it, it works again.
>>>>>>>
>>>>>>> The final page looks like a schematic of a scart cable (
>>>>>>> http://en.wikipedia.org/wiki/Scart) that is widely used in 
>>>>>>> Europe at
>>>>>>> least.
>>>>>>> I do also have a modified SCART cable that can be used to hook 
>>>>>>> up the
>>>>>>> RGB-output of a CoCo 3 to a normal television with a scart 
>>>>>>> input. That
>>>>>>> too
>>>>>>> once worked, but not anymore. Maybe if someone could help me 
>>>>>>> understand
>>>>>>> the
>>>>>>> schematic, and figure out what wires of a RGB-cable should be 
>>>>>>> connected
>>>>>>> to
>>>>>>> what pin of the scart, I could try to fix the cable or make a 
>>>>>>> few more
>>>>>>> for
>>>>>>> anyone interested... This would mean that a CoCo3 could be 
>>>>>>> connected
>>>>>>> from
>>>>>>> the RGB output directly to a television with scart input.
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> Fedor
>>>>>>>
>>>>>>> -- 
>>>>>>> Coco mailing list
>>>>>>> Coco at maltedmedia.com
>>>>>>> http://five.pairlist.net/mailman/listinfo/coco
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>
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