[GreenKeys] 33 stop bits

[Jones, Douglas W]

________________________________________
From: GreenKeys [greenkeys-bounces at mailman.qth.net] on behalf of Jim Haynes [jhhaynes at earthlink.net]
Sent: Saturday, May 10, 2014 12:39 PM
Cc: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] 33 stop bits

On Sat, 10 May 2014, Teletypeparts wrote:

> Using a test generator, I have found that some 33's will print fine with 1
> stop bit, but most need 2 bits to print correctly.  Just the peculiarity of
> the machine and its condition I guess.

And that's probably when you are generating more or less perfect signals.
________________________________________

Having just taken apart, degummed and begun reassembly of a 33,
I strongly suspect that the condition of the clutches would have a big
impact on this.  The arrival of the start bit engages the clutch on the
receiving cam cluster.  This cam cluster then engages each bit in
sequence as it spins one revolution.  As it finishes one revolution, the
clutch disengages and the cam cluster comes to a halt,  Any stickyness
in the trip levers that disengage the clutch, or stickiness in the cam
follower that re-enables the "listener" pawl for the start bit would have
an impact on the need for stop bits.  Small changes in oil viscosity in
the guides for the cam followers could do this.

                    Doug Jones
                    jones at cs.uiowa.edu