[Coco] Need help with composite output for CoCo

[embsys dev]

My coco is one of the early ones with a vertical rf modulator, so YMMV.

See link below for pics and schematic.

I desoldered the rf modulator (use a large gun but don't leave it on the
pads too long). I built the 2-transistor Frank Gilliland circuit on unclad
perfboard, and soldered it to the PCB pads via a pin header. The composite
RCA jack comes out the same place. Also ran the audio line up to an LM386
board that I hot-glued into the case top, which has a 3.5mm stereo jack
that comes out the TV channel switch hole (drilled out slightly).

Works!


https://drive.google.com/folderview?id=0B_i5frfkhXL8bzdzb1hIclhkZ0k&usp=sharing

On Sun, Feb 22, 2015 at 9:54 AM, Jamie <reinsj at nbnet.nb.ca> wrote:

> Ed,
> Here are pics of the two circuits I'm playing with and a pic of the more
> complex one, which is supposed to be the TV Buff circuit.  Both produce
> only a black screen. I also tried on an older CRT TV with video input with
> same results.
> https://drive.google.com/folder/d/0B4WhNfot4I2rbUhwdm9pWWptalk/edit
>
>
> Hi Jamie, Flat screen or not you should get a picture if you are
> generating a valid composite signal. Can you link the schematic of the
> circuit you’re using and pics of your installation? - Ed > On Feb 14, 2015,
> at 7:37 AM, Jamie <reinsj at nbnet.nb.ca> wrote: > > Hi All, > > So I'm
> trying to build a composite video converter for a coco 1 and I can't seem
> to get it to work. > I started with a simple design from Hot CoCo which
> uses a couple of transistors and a few > resistors and then tried Dennis'
> TV Buff. > My question is, should the output work on a modern flat screen
> LCD TV or do monitors with > composite input work differently? The TV
> screen responds by going black but I'm not getting any > picture at all. >
> > Thanks! > > Jamie > > > > -- > Coco mailing list > Coco at
> maltedmedia.com > https://pairlist5.pair.net/mailman/listinfo/coco
>
>
>
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