[GreenKeys] Computer Questioon

Tue Aug 18 21:54:20 EDT 2015

Don't most PC sound have cards capacitively coupled input & output?

Under those restrictions, you could maintain a signal LOW but not a HIGH..
the lowest freq. which can be passed is a function of the R-C constant
developed between the card's coupling caps, and the driving / driven
impedances.

No?

I've tried one of the PC sound card o-scope programs, and I don't think it
offered a DC coupling option. How can you transmit serial data of an
arbitrary baud rate over an AC coupled link?

On Tue, Aug 18, 2015 at 5:36 PM, Keith Densmore <ve3gem at gmail.com> wrote:

> Hi All,
>
> OK I am not the sharpest tool in the shed when it comes to computers. I
> know just enough to get myself in trouble.
>
>
>
> That said, I have a question.
>
> It seems that to interface a TTY to a computer you have the following
> possible contentions.
>
> 25 pin rs232 now obsolete
>
> 9 pin rs232 ditto
>
> usb 2.0 being upgraded to 3.0. Different drivers for different machines,
>
> Different versions of windows or Linux which affects the above.
>
> Not all drivers support low speed 45.5 or 50 baud.
>
>
>
> But when you interface through the soundcard you can
>
> use any soundcard
>
> use any computer
>
> support any slow speed desired.
>
> If someone has gone to the trouble of finding a mechanical TTY you can be
> pretty sure they have a converter with loop supply.
>
>
>
> ITTY is a great example. I can run it from my laptop or any other computer
> past or present.
>
> Wouldn't be simpler to have comms programs write/read to a soundcard
> instead of RS232? Or am I missing something here?
>
>
>
> Thanks,
>
> Keith ve3ts
>
>
>
> ---
>
> New Outlook Express and Windows Live Mail replacement - get it here:
>
> http://www.oeclassic.com/
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> Original Message:
>
> From: simon <simski at dds.nl>
>
> To: <greenkeys at mailman.qth.net>
>
> Sent: 2015-08-16 5:39:41 PM
>
> Subject: [GreenKeys] A reliable current-loop-to-RS232 converter
>
>
>
>
>
> On 16-08-15 02:21, Bob Camp wrote:
>
> > Hi
>
> >
>
> > The fine people “across the sea” will gladly sell you a RS232 <-> TTL
> converter mounted on a board with connectors.
>
> > Depending on how picky you are it may or may not cost you as much as
> lunch at MacDonalds (including shipping over
>
> > the ocean). If time is critical, the usual suspects here in the US will
> sell you a slightly fancier version (still fully assembled)
>
> > for a bit more.
>
> >
>
> > Bob
>
> >
>
> >
>
> >> On Aug 15, 2015, at 7:02 PM, drlegendre . <drlegendre at gmail.com> wrote:
>
> >>
>
> >> To convert the TTL level RS-232 signals to a proper bi-polar signal,
> you only need a MAX232 chip (or clone) and 4x 1uF @ 16V capacitors. The
> MAX232 directly converts back and forth between 5V TTL and the more correct
> +/-12V signaling.
>
> >>
>
> >> Easy as pie, and the chips are like a buck or something. Let me know if
> you need one, I have a couple spares.
>
> >>
>
> >> On Sat, Aug 15, 2015 at 3:24 PM, <teletypeparts at comcast.net> wrote:
>
> >> Justin,
>
> >>
>
> >> Thanks for your input. Gabriel's 33 is configured for full duplex,
> 20MA, 4 wire connection. That's the way I sent it to him unless I made a
> mistake, but don't think so as the cable on the UCC-6 was already in place
> and likely was used on a computer before. I just checked the connections
> and labeled the line cord end. 20MA is easy to check, just look at the
> large green resistor in the UCC-6 and the left tap should have a wire on
> it. 60MA, the wire goes to the inside tap. I also tested the machine with a
> signal generator at 20MA, full dux.
>
> >>
>
> >> I don't want to confuse the issue if possible. The 33 should work to a
> RS-232 adapter. The problem is there are so darn many and they don't have a
> good track record. I have seen lots of 33 owners struggle with this issue.
> It almost always came down to the RW-232 adapter.
>
> >>
>
> >> Best regards,
>
> >>
>
> >> Wayne
>
> >>
>
> >>>
>
> and maybe jump one conversion step with a usb to serial converter like
>
> the ftdi or a arduino leonardo with out of the box democode. dx.com and
>
> banggood.com have them in 5 and 3.3v versions
>
> http://www.dx.com/s/serial+usb
>
>
>
> And take a look here:
>
>
>
> wiki.edwindertien.nl/doku.php?id=modules:telex
>
>
>
> Simon (who implemented a version on a Raspberry Pi as the uart can talk
>
> any BAUD you like, for example 58baud (dont ask... long story))
>
>
>
> --
>
> Met vriendelijke Groet,
>
>
>
> Simon Claessen
>
> drukknop.nl
>
> ______________________________________________________________
>
> GreenKeys mailing list
>
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>
> Help: http://mailman.qth.net/mmfaq.htm
>
> Post: mailto:GreenKeys at mailman.qth.net
>
>
>
> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
>
> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>
> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
>
>
> This list hosted by: http://www.qsl.net
>
> Please help support this email list: http://www.qsl.net/donate.html
>
>
> ------------------------------
> [image: Avast logo] <https://www.avast.com/antivirus>
>
> This email has been checked for viruses by Avast antivirus software.
> www.avast.com <https://www.avast.com/antivirus>
>
>
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20150818/d6a10a58/attachment.html>