[Coco] 6847 Video (newbie question)

[Zippster]

The Y signal has to be inverted.

BTW this circuit won’t drive a component input on a television. (the ones I’ve tried anyway).
Well, luma gets decoded, but the levels don’t seem to match up for color (for modes
other than the text display on startup at least).

Interesting to hear it works with a GBS8220.

- Ed

> On Nov 1, 2014, at 9:34 AM, Brett Gordon <beretta42 at gmail.com> wrote:
> 
> I'm not an EE, but aren't CbOut and CrOut just emitter-followers?  I
> don't think they need ground. The current sink is the "grounding".  I
> Wonder why the "Y" has two transistors stuck on it.   One voltage
> inverter amp followed up by anther emitter follower (current amp).   Y
> must be inverted?
> 
> B
> 
> On Sat, Nov 1, 2014 at 9:48 AM, Retro Canada <retrocanada76 at gmail.com> wrote:
>> don't know about the pulldowns, i got the scheme from Daniel.
>> 
>> the image is pristine.
>> 
>> On Nov 1, 2014, at 6:19 AM, Tormod Volden <lists.tormod at gmail.com> wrote:
>> 
>> On Fri, Oct 31, 2014 at 10:03 PM, Luis Antoniosi (CoCoDemus)
>> <retrocanada76 at gmail.com> wrote:
>>> It works, but you need to make a driver:
>>> 
>>> https://pbs.twimg.com/media/BCb7-hoCEAAJm22.jpg:large
>> 
>> Shouldn't the CbOut and CrOut drivers have a resistor from emitter to ground?
>> 
>>> 
>>> When I used my it suffered from severe jumps time to time. maybe you have
>>> better luck and a better board.
>> 
>> Apart from the jumps, what does it look like? Perfectly sharp and
>> stable picture with good colours?
>> 
>> Regards,
>> Tormod
>> 
>>> 
>>> 
>>> Luis Felipe Antoniosi
>>> 
>>> 
>>> 
>>>> On Fri, Oct 31, 2014 at 3:58 PM, didier derny <didier at aida.org> wrote:
>>>> 
>>>> I just received a GBS 8220 and I was wondering if the YPBPR entries of the
>>>> GBS 8220
>>>> 
>>>> Were compatible with the Y phiA phiB of the 6847 ?
>>>> 
>>>> 
>>>> 
>>>> Are they the same signal with another name or something different ?
>>>> 
>>>> 
>>>> 
>>>> Not really understood fig 10 of the 6847 datasheet
>>>> 
>>>> 
>>>> 
>>>> I often used composite or rgb but never  YPBPR or the signal of the 6847
>>>> 
>>>> 
>>>> 
>>>> Any idea ?
>>>> 
>>>> 
>>>> 
>>>> Thanks
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> --
>>>> 
>>>> Didier
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
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>>> 
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> 
> 
> 
> -- 
> Brett M. Gordon,
> beretta42 at gmail.com
> 
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