[GreenKeys] Hello and Where to find PC to RTTY Interface?

[epvgk at limpoc.com]

Hi folks - 

A bunch of people have expressed interest in the FSK demodulator I made, one
of which I gave to Paul Cembura. It's just a straightforward application of 
the NJM2211 AFSK decoder chip pretty much right out of the datasheet, with an 
optical current loop interface tacked on. 

Basically you give it power and an audio signal (ie from a computer playing 
ITTY) and it keys a current loop circuit with the decoded data stream,
suitable for directly driving an actual teletype machine. It does not include
a loop power supply, as it's basically just an optical relay that opens and
closes. It's also receive-only - it doesn't modulate. You can adjust the
center frequency somewhat, and select wide or narrow shift. 

Paul and I have been using them for a while and it works fine for decoding 
ITTY and various stuff I've found on the Ham bands, but is by no means a 
sophisticated device. It does have the advantages of being tiny (2 by 2.5 
inch board), cheap (<$20 in parts), and easy to assemble (30 components total). 

I'm including the schematic in PDF format, and the eagle files are at:
http://xymoc.com/~eric/rttydemod/
If anyone wants gerbers or some other format, let me know. 

I'm thinking of having a run of about 20 of the bare board manufactured, 
which would run about $5 each at cost - if more than one or two people want 
one I'll do this just to make it easy. I can also include with it a parts list 
with Digikey part numbers so it's easy to order everything. Unfortunately I 
am so busy with work these days I'm not going to realistically have time to 
do preassembled ones. 

Anyway, I feel sort of silly putting this out there since it's a bit sloppy
and not anything at all innovative, but i'm happy to contribute if people
want it... 

eric

On Thu, Dec 30, 2010 at 02:08:52PM -0800, Bill wrote:
> 
> 
> On 12/30/2010 10:37 AM, epvgk at limpoc.com wrote:
> >On Thu, Dec 30, 2010 at 08:23:02AM -0800, Greg Farrell wrote:
> >>Hi All,
> >>
> >>I am brand new to RTTY hardware and this group, first posting. Had a problem with my email address since I send from my native account, not k6sro at arrl.net and got a  message back I was not on the member list, but I am. Changed my email address to gregf at pon.net so hope this works.
> >>
> >>
> >>Picked up a model 15 from Paul http://www.johnwhitney.com/misc/paul-rtty.htm yesterday.
> >>
> >>Thank you Paul.
> >>
> >>He demonstrated that machine with a little interface box from his laptop running ITTY.
> >>
> >>Where can I get this box or does anyone have a schematic/parts list for one?  It had an email address on it something like eric at linpoc.com but that doesn't work.
> >>
> >>TNX in advance.
> >>
> >>
> >>Greg
> >>K6SRO
> 
>     I would be very interested in this also.
> Thanks
> Bill Cain
> >hi, that's me :)
> >i can give you schematics and parts lists for that little box if you like, and if you have
> >patience could etch you a bare pc board for it. you'd be on your own assembling it but it's
> >a very simple circuit.
> >
> >eric at limpoc.com
> >
> >
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