[GreenKeys] Western Union Ticker-5A Stock Quotation Machine
eugene at hertzmail.com
eugene at hertzmail.com
Wed Apr 18 13:49:08 EDT 2007
I am certainly no expert on these matters. However, I do have a manual
and two 5A tickers. WA2HWJ was kind enough several years ago to get mine
working again. At the time, the best we were able to decipher, it was
6-bit, 50ma polar, 67.5 baud. It did seem to be start-stop. Manual
concurs with the start-stop. We were able to get RY and some other text
printing successfully. We encountered two main problems. 1) we only had
11/16 width paper available (as opposed to 3/4) which the ticker did not
like, the paper tended to walk around and not stay put. And 2) I had no
ink roller, so manual inking of the print wheel was only useful on a
temporary basis.
Teletype (non-bell written on cover)
Bulletin No. 137
Issue 2
January, 1934
Description and Adjustments
Of the
Typewheel Tape Printer (Ticker)
(for tickers bearing serial numbers above 1000)
My meager research tells me there were many variations on this ticker.
One was 5-level, one had a bid-ask delete capability and there were some
exterior changes such as the ink roller exposed vs. housed in a small
covering box. My two tickers have slight differences mechanically. Such
as the shape of the typewheel stop pins.
I can quote from the manual under "CODE" page 1---
The signaling code employed to transmit characters in a six unit
"start-stop" code which consists of six selecting impulses used in
various combinations of positive and negative intervals. Each group of
six selecting impulses is preceded by a start impulse and followed by a
stop impulse to maintain unison between the transmitting apparatus and
the printers."
On page -31- of this publication it mentions:
Coil Resistance and Operating Currents
Color of Leads USE Coils in Series Parallel Resistance
(per coil)
Green/White W.U. 50ma 100ma 39 ohms
Blue/Yellow - - - 15 ohms
Red/Yellow N.Y.Q. 100ma 200ma 8 ohms
N.Y.Q. is New York Quotation, the service provider of the quotes for
stock exchanges (I also have a NYQ ticker with glass dome)
Interesting enough, I also have a manual from "Morkrum-Kleinschmidt"
Bulletin No. 136, December 1928
This is very similar to the one dated 1934 but has some differences.
Line current is stated only at 50ma when coils are connected in series
and 100ma in parallel and operating coil resistance as 37 ohms each
Last bit of evidence, I have a sheet "Specification 60,660S" December
13, 1963 which has hand written on it "Canadian Ticker 135 Baud, 15.0
wpm" No idea of that makes any sense.
I had hopes of getting my 5A online but I could never find 3/4 inch tape
to continue experimenting.
Hope this has helped in some small way
Eugene
-----Original Message-----
From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Brooke Clarke
Sent: Wednesday, April 18, 2007 1:01 PM
To: Bob Camp
Cc: GreenKeys List
Subject: Re: [GreenKeys] Western Union Ticker-5A Stock Quotation Machine
Hi Bob:
Now we're cooking.
The 5-A coil is 0.15 H, 20 Ohms and let's say 60 ma operation.
The printing rate is 500 characters per minute with 6 bits per character
(no
start, no stop bits) or 3,000 bits per minute, or 50 bits per second, or
20 ms
per bit. i.e. half that baud rate you mentioned. So the time interval
might
be T = 1/500 or 0.002 seconds.
Now: V = L * dI / dT = 0.15 * 0.06 / 0.002 = 4.5 volts which is close
enough
to a standard 5 volt logic supply.
Thanks for an explanation I could get my teeth into!
How do the coil specs for the 5-A compare to the ASR-33 that I used to
use with
my first computer?
Have Fun,
Brooke Clarke, N6GCE
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Bob Camp wrote:
> Hi
>
> Yes, some have done the experiment you describe. In my case it was
> sometime in the late 1960's (gulp!) . Results:
>
> 1) With the diode on the coil the system simply does not work at all.
> The magnetic field does not collapse fast enough to release the
> armature in time. It's not a matter of distortion in this case, it's
a
> matter of not having any copy at all.
>
> 2) The high voltage on "break" allows the energy to be dumped faster.
> When the volts X amps is higher the coil dumps it's stored energy in
a
> shorter period of time.
>
> 3) In order for the mechanical part of the system to work correctly
the
> electrical signals need to be pretty accurate. Any significant
> distortion in the electronics mucks up the mechanical side pretty
fast.
>
> Here's some math ....
>
> The basic formula for current in a coil is:
>
> voltage = inductance X (delta current) / (delta time).
>
> At 100 baud and 10% distortion T = 1/1000 of a second.
> Current is about 60 ma.
>
> so:
>
> V = L x 0.060 / 0.001
> V = 60 * L
>
> That's for a constant current loop ...
>
> If L is in the roughly couple of Henrys range then you get voltages
at
> or above 60 for any reasonable level of distortion.
>
> Bob
>
>
> On Apr 18, 2007, at 12:34 AM, Brooke Clarke wrote:
>
>> Hi Peter:
>>
>> Did you try using a current source instead of a voltage source? Did
>> you use a protection diode across the coil?
>>
>> I've been studying this for most of today and I've found two key
>> factors.
>>
>> 1) the loop time constant is L / R. It may take 3 to 5 time
>> constants for a signal to settle so the time constant needs to be a
>> very small part of a bit time or you're going to have problems. But
>> using a current source brings the time constant near zero, i.e. R is
>> near infinity.
>>
>> 2) the coil in the electromagnet does not like to change currents.
>> If there is already current in the coil and you turn it off the coil
>> tries to generate a voltage that's high enough to maintain the old
>> current. This is how the spark coil in a car works. This voltage
>> pulse can easily destroy the driver transistor. The common way of
>> fixing that is to put a diode across the coil with it's polarity
such
>> that when the coil is forward biased the diode is back biased, but
>> (forgetting about the bi polar drive for a minute) that will not
work
>> and at the same time allow the coil to operate quickly, instead the
>> diode slows the coil way down since now there's a current
circulating
>> in the diode and coil with it's own long L/R time constant.
>>
>> I think the fix for (2) is to use a bi polar Transil. It's sort of
>> like back to back zener diodes (which probably would also work) with
>> a breakdown voltage greater than the DC drop across the coil when
>> saturated but much much faster and rated to absorb spikes.
>>
>> I'd like to hear from someone who has done this type of experiment.
>> My gut feeling is that a properly designed driver can work with a
low
>> voltage supply. My brain is telling me that there's a lot of people
>> using high voltage that would not be if there was an easy way to
>> avoid it.
>>
>> Have Fun,
>>
>> Brooke Clarke
>> w/Java http://www.PRC68.com
>> w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
>> http://www.precisionclock.com
>>
>>
>>
>> Peter Gottlieb wrote:
>>
>>> Well obviously a power op-amp (Burr-Brown) or homebrew
>>> (complimentary pair, see National app notes) will take RS-232 and
>>> make bipolar.
>>> I am not too familiar with the dynamics of polar relays but TTY
>>> selector magnets need a high voltage to get current into the high
>>> inductance rapidly. I couldn't get my 2B to run at 28 volts even
>>> though I needed a series resistor to drop the current, but go to
100
>>> and it ran like a champ.
>>> Peter
>>> Brooke Clarke wrote:
>>>
>>>> Hi:
>>>>
>>>> I'm trying to bring a Western Union Ticker-5A Stock Quotation
>>>> Machine back to life. This is the machine that replaced the older
>>>> stock ticker machines that were under glass domes to keep down the
>>>> noise. I'd say that it's father was the Edison Universal stock
>>>> ticker that changed Edison from someone who was broke to a multi
>>>> millionaire. It's mother was the model 26 Teletype machine since
>>>> they both use a similar, but not interchangeable, selector cage.
>>>>
>>>> It's my understanding that the 26 was good for 100 CPM yet the 5A
>>>> was good for 500 CPM.
>>>>
>>>> The 5A uses a permutation code that consists of 5 bits but instead
>>>> of using a character for shift to numbers and another character
for
>>>> shift to letters the 5A uses another code bit for this so the
total
>>>> number of bits in the code is 6. This solves the stuck in figures
>>>> problem.
>>>>
>>>> But unlike teletype machines the 5A does NOT use start and stop
>>>> bits. This is one of the things that makes it fast.
>>>>
>>>> The thing I'm working on now is how to drive it. The input goes
to
>>>> a polar relay that expects to see current polarity reversals, not
>>>> the on off keying that a normal teletype machine uses. Testing
has
>>>> revealed that it wants to see 50 to 100 ma and being a 20 ohm coil
>>>> a little over 1 volt is all that's required.
>>>>
>>>> Are that circuits already in existence that will take in RS-232
and
>>>> supply the bi polar drive current? I think that might be more
>>>> common in the UK or Australia than in the US.
>>>>
>>>> Why do teletype machines typically have loop voltages in the 100
to
>>>> 200 volt area? Could these be replaced by current sources that
>>>> have a voltage compliance a litter higher than the voltage drop
>>>> across the input relay coil?
>>>>
>>>> For more on the 5A see my web page:
>>>>
>>>> http://www.pacificsites.com/~brooke/WU5A.shtml
>>>>
>>>> Have Fun,
>>>>
>>>> Brooke Clarke, N6GCE
>>
>> _______________________________________________
>> GreenKeys mailing list
>> GreenKeys at mailman.qth.net
>> http://mailman.qth.net/mailman/listinfo/greenkeys
>>
>
_______________________________________________
GreenKeys mailing list
GreenKeys at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/greenkeys
More information about the GreenKeys
mailing list