[GreenKeys] Dow Jones Broad Sheet News Printer

[John Nagle]

On 4/3/2013 3:17 AM, greenkeys-request at mailman.qth.net wrote:
> From: Brooke Clarke <brooke at pacific.net>
> To: greenkeys at mailman.qth.net
> Subject: [GreenKeys] Dow Jones Broad Sheet News Printer
> 
> I'm looking for any information about the Dow Jones broad sheet news printer.
> http://www.prc68.com/I/DJnews.html

    Look at the patents mentioned on the number plate.  Those
will help.

    That really is a "ticker", rather than a start-stop
machine like a Teletype.  The clock-escapement device that
advances the typewheel is what makes it a "ticker".  Technically
it's a successor to the glass-dome type tape printer stock tickers.
(The WU 5A High Speed Stock Ticker, on the other hand, is a
6-level stop-start serial mechanism like a Teletype. )
The 1832160 patent, which describes the carriage advance mechanism,
and mentions that the wheel drive is a step by step mechanism.

    The input to a "ticker" is two signals - one advances the
typewheel one notch, and the other prints at the current typewheel
position.  This, of course, creates a sync problem.  Edison's
first major invention was a solution to that problem.  Sync
usually involves some kind of resync on long pause or long
pulse.  There are many approaches to this problem; there's
a whole patent category called "unison devices" for this.

    As with a clock, the escapement does not power the
the mechanism.  The escapement holds back the mechanism.
Here, the mechanism is driven by a motor through a slip clutch.

    Ticker line inputs are usually polar - the line reverses
DC polarity, rather than turning on and off.  Expect the
escapement coils to work that way too; they probably require
a reversing DC signal.

    The bottom solenoid probably somehow triggers the long hammer
behind the paper, which drives the paper against the typewheel
for a print cycle.

				John Nagle