[GreenKeys] M28 KBD mounted idle line timer...

[Kenneth Gartland]

Hi all...

Henning has raised an interesting question about motor control (Idle line
timer) on the M28 Teletype model line...

There is indeed an "Idle line" time mech. mounted on the kbds of
most M28 Teletypes, KSR's & ASR's...I am not sure if the RO base has it...

Its' simplicity is its' beauty...It is basically a parallel ratchet
wheel device, which has
two ratchet wheels, one with a slightly different "Tooth" pitch from the
other, thus rotates, slightly faster...When the ratchet drive lever is
engaged,(an adjustable feature), it can be optioned either in or
out... In the "In" setting, the wheels after a minute or so, "Line up"
and a switch activation lever underneath rides into a detent created
by the parallel ratchet wheels being side by side for a moment...In
the "Out" position, the feed lever is mechancially raised so as to
clear the ratchet wheels.

Pretty nifty...

There is an associated relay mounted on the LESU, Not present on all
versions, but on most...When the line has been idle for over a minute or so,
the motor will shut off and stay off until the next start bit of an incoming
character is detected, and the motor turns on again...

To return to Henning's question, the M28 line can be readily adaptable
for i-Telex operation...

The dialer and ansback requirement can be a tuff call, as there isn't
much of this equipment around...Western Union used quite a few KBD
mounted answer backs on the their M28KSR and ASR versions for Telex svc.
Also there is a unit called an LABD500, which is a self contained ansback
mech, based on the M32/33 distributor/contact block design...
So, all in all, the 28 is a great machine for i-Telex...

I have been using i-Telex for a couple months now, and just love
it...

Fred and Henning have done an incredible job of designing this system...
It precisely emulates the original Siemens TW-39 Telex exchange and
dial-up protocol...

Well worth looking into!

Cheers!

Ken VE3-HMQ
i-Telex 61663