[GreenKeys] Re:I hope you can help. Jan Bogue KD6EMW W15 page printer with perf

[gil smith]

Jan:

At 10:29 PM 11/7/2004, Wndrrt at cs.com wrote:
>What does this mean: "I patched the kb/sel in series for half-duplex testing
>with an external loop supply and current limit resistor."  So the loop is
>external?

I explained some of this loop stuff earlier, so maybe this makes sense 
now.  If you isolate your M15 wiring such that you bring out the two wires 
for the selector magnets (for the typing unit), and the two wires for the 
keyboard contacts (the keyboard is just a mechanized switch), you can 
connect to two loops (rx and tx) for full-duplex use.  Or, you can wire 
them in series (four wires now become two), for a half-duplex loop.  In 
half duplex, you can type on the keyboard, and see it print on the typing 
unit.  This is the first test for a machine:  a series connection of the 
loop supply, keyboard, and typing unit.  When this is working, you can 
insert the TD and try tape reading.  Then insert a computer interface or 
TU/radio adapter...

>What do these loops look like, do they eat much, do they come in packs
>or flocks?

I think it would be a gaggle of loops.  Or is it a horde?


>Do they plug in under my table into the large I think red and
>green phone plugs?

The red plug will be the TX loop (keyboard, and likely TD), and the green 
one will be the receive loop (typing unit).  Note that when the TD is not 
installed, contacts in the mounting plate will close that loop for 
you.  Same is true for the keyboard -- pull it out and contacts close the 
connection.  So if they are wired into a loop circuit, you can remove them 
for servicing, and not break the loop.

However, there is a lot of wiring in an M19 table, and the table may be set 
up for a "polar" loop.  A polar loop is designed for longer lines, and uses 
current flow in two directions, instead of the on/off keying of a neutral loop.

I would advise tracing out the wires from the selector magnets, keyboard, 
and TD, and bringing them out on three separate pairs of wires (with 1/4" 
plugs).  You can then connect to simple neutral loops, and can externally 
patch them for half- or full-duplex use as needed.  You can modify the 
wiring at the terminal strips without the need to cut any original wiring.


>Here is another one:  "clickety-clack! Adding loop power (kb and printer in
>series....????????????) stopped the chattering."

When the typing unit's selector mags have no current flow, the machine runs 
"open."  This means a lot of the mechanism is chattering away doing nothing 
at all.  When you put 60 mils through the selector magnet (a solenoid, 
really), the machine quiets down to the standby state, waiting to see a 
start bit followed by 5 data bits and finally a stop bit -- it then prints 
a proper character (or rings the bell, or returns the carriage...).  The 
keyboard does not need to be connected for this.


>And finally:  "Watching the M15 print is most satisfying.  Now I want to set
>up Bill Buzbee's Heavy Metal program to automatically print selected 
>emails."
>I want fun stuff too, but how did you interface one of those rare long haired
>hard to catch current loops to your computer?

Just so happens that I have some info on that:
http://www.vauxelectronics.com/gil/tty-connect/

gil



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