[Coco] CoCo 3 RGB to SCART video, then converted to HDMI

Fri May 1 06:11:12 EDT 2015

Salvador, we dont have reason to not believe you.

Its just a matter of taste. What would be good for you might not be good for others to justify buying this.

There are other alternatives and having pics will help people getting the one that better suits them.

Sent from my iPhone

> On Apr 30, 2015, at 11:29 PM, Bill Pierce via Coco <coco at maltedmedia.com> wrote:
> 
> Thanks Salvador, you beat me to it :-)
> 
> What he said....
> 
> 
> 
> 
> 
> 
> Bill Pierce
> "Today is a good day... I woke up" - Ritchie Havens
> 
> 
> My Music from the Tandy/Radio Shack Color Computer 2 & 3
> https://sites.google.com/site/dabarnstudio/
> Co-Contributor, Co-Editor for CocoPedia
> http://www.cocopedia.com/wiki/index.php/Main_Page
> E-Mail: ooogalapasooo at aol.com
> 
> 
> 
> 
> 
> 
> -----Original Message-----
> From: Salvador Garcia <ssalvadorgarcia at netscape.net>
> To: coco <coco at maltedmedia.com>
> Sent: Thu, Apr 30, 2015 11:24 pm
> Subject: Re: [Coco] CoCo 3 RGB to SCART video, then converted to HDMI
> 
> 
> 
> 
> 
> but, well, if you don't believe me, I'm not really concerned,
> believe what
> you want,
> 
> 
> He said that in a jokingly affectionate manner and was a humorous
> way to request pictures. A tendency here is that we all like (love?) to see
> pictures (and when possible videos) of others' projects and it seems as though
> your project caused well deserved attention for its ingenious simplicity.
> Salvador
> 
> 
> -----Original Message-----
> From: Barry Nelson
> <barry.nelson at amobiledevice.com>
> To: coco <coco at maltedmedia.com>
> Sent: Thu, Apr
> 30, 2015 5:17 pm
> Subject: Re: [Coco] CoCo 3 RGB to SCART video, then converted
> to HDMI
> 
> 
> Responding to some of the comments…
> First, I will try to post pictures
> and a
> video soon, but, well, if you don't believe me, I'm not really
> concerned,
> believe what you want, I'm just trying to share the information, but
> my setup,
> at least with the converter I have, works very well. As to using pins
> 8 & 9,
> there are a few issues:
> 
> 1) The signal level is very low, less than 2V
> peak to
> peak. (It is NOT TTL)
> 2) The polarity is positive instead of
> negative.
> 3) The
> signal on those pins is a simple square wave, it has no "back
> porch" or "front
> porch" levels on the vertical sync line.
> 4) Their timing and
> pulse shape may be
> ok for a CM8 monitor, but nothing else seems to like them.
> 
> I
> am sure all these
> issues could be resolved with the right circuitry and time,
> but why complicate
> things needlessly?
> 
> The sync signals on the composite video
> line have the right
> timing and include the front and back porch levels, and my
> SCART converter seems
> to happily ignore the other "stuff" on that line when it
> is in RGB mode. Maybe
> an LM1881 might provide a cleaner signal, but it does not
> seem to be necessary
> as the picture is clean and stable.
> 
> I have no plans to
> manufacture cables at
> this time, but anyone else is welcome to use the pinout I
> provided and make
> their own cable.
> 
> I got the idea for this after attempting a
> couple of other
> solutions, and researching the the signals and voltage level
> output from the
> CoCo. I found that the RGB signal levels and timing matched
> almost exactly what
> a 480i SCART signal looked like, and the voltage levels and
> timing on the
> composite video line were a match for the sync pin on the SCART
> connector.
> Interestingly, a side effect of this is that if you disconnect the 5V
> line from
> the 100 ohm resistor, the SCART switches off the RGB signals and uses
> the
> composite video instead, so with one video connection you can actually
> switch
> from RGB monitor mode to TV mode by toggling this voltage on or off.
> 
> On
> Apr 30,
> 2015, at 10:07 AM, coco-request at maltedmedia.com wrote:
> 
>> Date: Thu, 30
> Apr 2015
> 08:37:57 -0500
>> From: Dave Philipsen <dave at davebiz.com>
>> To: CoCoList
> for
> Color Computer Enthusiasts <coco at maltedmedia.com>
>> Subject: Re: [Coco] CoCo
> 3
> RGB to SCART video, then converted to HDMI
> Message-ID:
> <55423035.2060703 at davebiz.com>
>> Content-Type: text/plain;
> charset=utf-8;
> format=flowed
>> 
>> If you have a problem with a circuit that just
> needs the sync
> signal(s) 
>> from a composite video source there is an
> inexpensive chip that
> will 
>> strip the sync for you.  It is an LM1881.
> Dave Philipsen
>> 
>> 
>> On
> 4/30/2015 6:09 AM, Steven Hirsch wrote:
>>> On Thu, 30
> Apr 2015, Barry Nelson
> wrote:
>>> 
>>>> I have conducted an experiment and it
> worked! I wired the CoCo
> 3's 
>>>> RGB video lines from the connector on the
> bottom of the computer to
> 
>>>> the RGB lines in an SCART connector. I connected
> the audio from the 
> CoCo connector to the left and right audio on the SCART
> connector. I 
> connected the CoCo 3's composite video to the composite
> video/sync on 
>>>> the
> SCART connector and I connected +5V to a 100 ohm resistor
> 
>>>> connected to the
> "fast switching" pin on the SCART connector. I then 
> plugged the SCART video
> connector into my SCART --> HDMI converter, 
>>>> which I
> plugged into my TV.
> Viola! Perfect RGB video up scaled to 1080P.
>>> 
>>> From my
> experience with
> other classic machines, use of composite video 
>>> as composite
> sync for SCART
> is hit or miss.  Glad it worked out for you!
>>> 
>>> Would love to
> see some
> photos of 80-column text mode.
> 
> ------------------------------
>> 
>> Date: Thu, 30 Apr 2015 09:49:05
> -0400
> From: Michael Rowen <mike at borncoco.com>
>> To: CoCoList for Color
> Computer
> Enthusiasts <coco at maltedmedia.com>
>> Subject: Re: [Coco] CoCo 3 RGB to
> SCART
> video, then converted to HDMI
> Message-ID:
> <rlrrdi1gf0sx336815c38tag.1430401745551 at email.android.com>
> Content-Type:
> text/plain; charset=utf-8
>> 
>> I would think the coco RGB
> vertical/horizontal
> (pins 8 &9) inverted through a 74LS02 (Nor gate) would work
> to the sync line on
> the scart. This is very cool. I'm going to try this
> myself.
>> 
>> This device
> also converts composite to HDMI. With Ed's awesome
> composite boards for the
> Coco2, might do a decent job for a Coco2 as well.
> I found several YouTube
> vids for this same device used with various gaming
> consoles via scart. Just
> search for scart.
>> 
>> -Mike
> 
> 
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