On 4/15/2010 6:11 AM, David Griffith wrote:
I think the Mark and Space stuff has to do with the
fact that the line was always kept energized, thus, an idle line would
hold the sounder arm down. That way you'd know immediately if there was
a line fault. That would be a bit wasteful now, so I suppose I should
preceed each message with a very long dash to at least try to fake that
part.

The original Morse instrument was a device which used a scribe to
imprint a line on a paper tape which was moving past the scribe arm
under tension from a clockwork mechanism.

When the electromagnets were energized, the scribe would make a mark on
the tape. When they weren't, the tape would "space" past the scribe
point without being marked.

Ergo, "Mark" means current in the loop, "Space" means no current. The
early telegraphs were powered by batteries.

There is software available to do what you want to do: visit the Morse
Telegraph Club, http://www.mtc.org/ , for more information.

HTH.

73,

Bill W1AC

On Apr 15, 6:11 am, (David Griffith) wrote:
When the key is down, the sounder clicks down. Let go and
it clacks up. So, a dot is "click-clack" and a dash is
"click-wait-clack".

With most sounders, the sound of the armature going down is different
from the sound going up, as you describe, so it's more than the time
spacing.

I think the Mark and Space stuff has to do with the
fact that the line was always kept energized, thus, an idle line would
hold the sounder arm down. That way you'd know immediately if there wa
s
a line fault.

Yes, but there were several reasons for the normally-energized series
line systems.

1) The first systems were powered by wet primary batteries called
"gravity" cells. (You can still make your own - all you need is
copper, zinc, copper sulphate, water and a jar). Unlike most other
kinds of cells, the gravity cells need a load for best results.

2) The primary cells required a lot of maintenance and care. With a
normally-energized system, line batteries were needed only at the ends
of a line; the telegraph offices in between would not need them
(except a cell or two for local loops). A typical line battery would
consist of 100 to 200 gravity cells (often half the cells would be at
each end) and permit operation over lines of 100 to 400 miles,
depending on the wire size and number of intermediate stations. (#9 or
#6 iron wire was commonly used for telegraph lines). So you can see
the advantage of not needing line batteries everywhere!

3) Besides making a line break obvious, operation up to a break could
be had by grounding the line at the last convenient point before the
break.

4) Normally energized circuits made duplexing, multiplexing and other
systems easier to implement.

The wire telegraph was more sophisticated than some folks give it
credit for being.

----

A telegraph story:

There was a railroad which had an important position open at the
division office. Applicants were told to show up on a certain day in
the outer waiting room, and wait to be called into the
Superintendent's private office for an interview.

The outer waiting room was a busy place, with a telegraph sounder
going continuously, various employees doing all sorts of tasks, and
the Superintendent inside his private office with the door shut.

A number of applicants showed up, most with years of experience. Each
handed their papers to the clerk, took a seat, and waited.

After all the chairs were occupied, a young man arrived - obviously
not nearly so experienced as the others. He paused for a moment,
papers in hand. Then he walked straight to the door of the
Superintendent's private office, opened it, and walked right in,
closing the door behind him!

The other applicants looked at each other in surprise and some
amusement. Barging in on the Division Superintendent was the best
guarantee of never getting any job! One waiting applicant said the
word "greenhorn" and the others all nodded.

But a few moments later, the door of the Superintendent's office
opened, and the Superintendent came out, followed by the young man.
The Superintendent said: "Thank you all for coming, but the position
has been filled." It was obvious that the young man had gotten the job
they all wanted.

Some of the applicants started to protest, but the Superintendent just
pointed to the telegraph sounder. It wasn't on an outside line. It was
playing the same message over and over:

"If you can read this, come into my office"

73 de Jim, N2EY

The

David Griffith wrote:
Michael J. Coslo wrote:
On Apr 14, 2:46 am, "D. Stussy"
wrote:
"David Griffith" wrote in message

...

Does anyone here done something like sending ASCII to a microcontroller
which then emits morse code? I'm tinkering around with old telegraph
sounders.
Yes. I re-wrote the firmware in my Icom repeater, which included the I
D
section too.

Here's a webpage where a fellow has done something similar:

http://www.steampunkworkshop.com/

It's on the right hand side of the page, a link called "telegraph
sounder"

http://www.steampunkworkshop.com/telegraph.shtml

That's one of the first places I looked and where I got the idea.
However, what he did was have a circuit watch the keyboard LEDs. What
I'm trying to do is make something that attaches to an RS232 port. That
way, I can run a three or four wire cable from a server in a back room
to wherever I decide to put my sounder. There are two ways I could do
this. The first is cheap and dirty. It works by energizing the sounder
coils whenever RTS is asserted. That would require special program --
not too tough, but won't be as flexible as in the second approach. The
other is to buffer RS232 in a microcontroller, convert to morse code,
then tap out the message. In effect, this creates a one-way
serial-to-telegraph modem. That second approach is what has me most
interested. Suppose you have a server writing logs to a serial port...
See the sort of bizzare fun that can be had?

Absolutely!

I would think something like this would be fairly easily done in an
Arduino or basicStamp.

The hardware would be near trivial -- get the thing some power, provide
a RS-232 driver, and a open-collector transistor to drive the sounder.
(what kind of voltage/current does a sounder want?)

You'd have plenty of spare output lines (since you only need one to
drive the sounder!) so you could generate a keyed tone on another
output for driving a speaker, useful once you find out why they
dropped sounders like a hot rock once someone invented the BFO(grin)!

--

Doug Smith W9WI
Pleasant View, TN EM66

wrote:
David Griffith wrote:
That's one of the first places I looked and where I got the idea.
However, what he did was have a circuit watch the keyboard LEDs. What
I'm trying to do is make something that attaches to an RS232 port. That
way, I can run a three or four wire cable from a server in a back room
to wherever I decide to put my sounder. There are two ways I could do
this. The first is cheap and dirty. It works by energizing the sounder
coils whenever RTS is asserted. That would require special program --
not too tough, but won't be as flexible as in the second approach. The
other is to buffer RS232 in a microcontroller, convert to morse code,
then tap out the message. In effect, this creates a one-way
serial-to-telegraph modem. That second approach is what has me most
interested. Suppose you have a server writing logs to a serial port...
See the sort of bizzare fun that can be had?

Absolutely!

I would think something like this would be fairly easily done in an
Arduino or basicStamp.

The hardware would be near trivial -- get the thing some power, provide
a RS-232 driver, and a open-collector transistor to drive the sounder.
(what kind of voltage/current does a sounder want?)

You'd have plenty of spare output lines (since you only need one to
drive the sounder!) so you could generate a keyed tone on another
output for driving a speaker, useful once you find out why they
dropped sounders like a hot rock once someone invented the BFO(grin)!

I suppose the next thing to do is look for a good simulator that runs on
Linux.

The power requirements of sounders depend on the ohm ratings of the
coils, which is usually stamped somewhere on the sounder. The lower the
ohms, the lower the voltage requirements. Some modern things need to be
done like adding more resistance so it won't be too sluggish. Also a
pair of zeners back-to-back is recommended to prevent something (I
forget what).

Another thing I'll need to use a few lines for would be some means of
varying the output speed. Yes, an alternate output could ride along for
free. Perhaps also a relay to go to the key input of a radio.


--
David Griffith
--- Put my last name where it belongs

N2EY wrote:

Yes, but there were several reasons for the normally-energized series
line systems.

Another thing is that telegraph "lines" might indeed be a single wire..
Using the Ground as the "Return" for the loop

This was often done both for telegraph and for mains electrical at one
time due to a shortage of metal for the wires... This is very likely why
house systems have a ground bonded to the neutral at the service
entrance AND AT THE POLE.. At one time they simply forgot to use a neutral.

Plus I"ve seen several "Loop" systems today where a single wire is
looped from the "Central office" out to each "node" or station and all
the way back.. One such was made by Phillips back in 1980.. I used to be
one of the operators (This was a telephone system) the finished product,
I used to joke, had one part that NEVER FAILED... That was a reset
button... The original failed and the replacement came from Radio Shack.

On Apr 16, 10:20 am, John from Detroit wrote:
N2EY wrote:
Yes, but there were several reasons for the normally-energized series
line systems.

Another thing is that telegraph "lines" might indeed be a single wire..
Using the Ground as the "Return" for the loop

It is my understanding that many of them were. Besides the savings in
wire and insulators, a ground-return system could actually be lower
resistance than a double-wire system if the "made grounds" at the ends
of the lines were very good.

Of course such a line is more vulnerable to noise, but since the wire
telegraph was a digital system the nouse would have to be considerable
to have any effect.

73 de Jim, N2EY

N2EY wrote:
On Apr 16, 10:20 am, John from Detroit wrote:
N2EY wrote:
Yes, but there were several reasons for the normally-energized series
line systems.

Another thing is that telegraph "lines" might indeed be a single wire..
Using the Ground as the "Return" for the loop

It is my understanding that many of them were. Besides the savings in
wire and insulators, a ground-return system could actually be lower
resistance than a double-wire system if the "made grounds" at the ends
of the lines were very good.

Of course such a line is more vulnerable to noise, but since the wire
telegraph was a digital system the nouse would have to be considerable
to have any effect.

That thing about noise reminded me of a story about a severe magnetic
storm that happened in the 1880s or thereabouts. Currents induced into
telegraph lines were so strong that things caught fire in telegraph
offices as well as simply knocking them offline.

--
David Griffith
--- Put my last name where it belongs

David Griffith wrote:
N2EY wrote:
On Apr 16, 10:20 am, John from Detroit wrote:
N2EY wrote:
Yes, but there were several reasons for the normally-energized series
line systems.
Another thing is that telegraph "lines" might indeed be a single wire..
Using the Ground as the "Return" for the loop

It is my understanding that many of them were. Besides the savings in
wire and insulators, a ground-return system could actually be lower
resistance than a double-wire system if the "made grounds" at the ends
of the lines were very good.

Of course such a line is more vulnerable to noise, but since the wire
telegraph was a digital system the nouse would have to be considerable
to have any effect.

That thing about noise reminded me of a story about a severe magnetic
storm that happened in the 1880s or thereabouts. Currents induced into
telegraph lines were so strong that things caught fire in telegraph
offices as well as simply knocking them offline.


Friend of mine hooked a very high impedance volt meter to his long wire
antenna one storm and got some very interesting voltmeter readings

Several volts (As in 3 digits) as I recall.. Of course it did not take
much current to ground it out but it was amazing the amount of voltage
on that wire.

My Long wire is DC-Grounded so I don't see that.

David Griffith wrote:
I suppose the next thing to do is look for a good simulator that runs on
Linux.

The Arduino development environment is, if I recall properly, written
in Java & should run on Linux. Don't know about a simulator.

The power requirements of sounders depend on the ohm ratings of the
coils, which is usually stamped somewhere on the sounder. The lower the
ohms, the lower the voltage requirements. Some modern things need to be
done like adding more resistance so it won't be too sluggish. Also a
pair of zeners back-to-back is recommended to prevent something (I
forget what).

Voltage spikes, which could kill the driver. I don't really have a
handle on the magnitude of the current involved in running a sounder,
but I think you'd almost certainly want some kind of driver stage (a
transistor or two, depending on the current requirements) between the
microcontroller and the sounder. Spike protection would be part of
that circuit.

Another thing I'll need to use a few lines for would be some means of
varying the output speed. Yes, an alternate output could ride along for
free. Perhaps also a relay to go to the key input of a radio.

Arduino has analog inputs which could be connected to a potentiometer
for varying the Morse speed.

--

Doug Smith W9WI
Pleasant View, TN EM66