[GreenKeys] 5-A Teletype stock ticker on eBay

[John Nagle]

Here's an exotic Teletype product - the 5-A stock ticker.

http://www.ebay.com/itm/Western-Union-Black-Box-Ticker-5-A-Stock-Quotation-Machine-Teletype-/251614845500

$250, plus shipping.  Condition looks very good.  No sign of rust,
damage, or even dirt.  Comes with the "Description and Adjustments"
manual. Some museum should pick this up.

This is the "high speed stock ticker" introduced in the 1930s.
It's a 6-level start-stop machine with no shifts.  Compatible
with nothing but some central stock quote transmitter. Input
is polar - rather than MARK and SPACE, the line polarity is
reversed. This follows previous stock ticker practice,
so they didn't have to change the distribution network
when the machines were changed.  Someone did figure out how
to drive one with a PIC and an H-bridge:

http://www.prc68.com/I/WU5A.shtml

The description there is kind of confusing. I get the impression
that early 5-A models had some kind of backwards compatibility
mechanism so they could interoperate with older step-by-step
tickers.  Later models were just 6-level start-stop machines.

Unlike the Edison glass dome tickers, which are expensive
collectables, the 5-A, which isn't very pretty, never
caught on with collectors.

I have no connection with this.

				John Nagle