[GreenKeys] Hughes Printing Telegraph

[John Nagle]

On 7/19/2011 12:56 PM, greenkeys-request at mailman.qth.net wrote:
> From: W2HX<w2hx at w2hx.com>
> Subject: Re: [GreenKeys] Hughes Printing Telegraph
> To:GreenKeys at mailman.qth.net
> Date: Tuesday, July 19, 2011, 12:50 PM
>
> Oops. I've been so excited with this new toy that my math has gone out the
> window!
>
> Today I slowly powered up the motor. Field coil and stator(?) coils all have
> continuity. The document from Sam Hallas indicated a 46V Battery. We started
> at 12V and worked out way up.  At 46V the motor barely had any pull. Total
> current was about 125mA.  So we (a friend and I) moved up slowly in 12V
> chunks up to about 76VDC where it started to run.  We surmised that this may
> have had a 110VDC motor installed. Who knows what in Germany (and the age of
> the unit) might have been different than the one described in the PDF.
>
> So we made a video (see link below). It seemed at first that no matter what
> polarity we used, the motor only wanted to run backward. We realized that
> the field coil is connected in series and therefore the polarity would not
> matter.  We also realized that there was a repair made at one time on the
> motor (probably in a museum or private collection) and the field coil was
> connected reversed. We fixed that and now the unit runs like a top! But it
> is running way too slowly still.

    Wow. Over a century old, and the motor starts when you apply power.
I'm impressed.

> One point of interest. At first we ran this, all of the clockwork was
> running too (from the electric motor). We then discovered one of the gears
> had a set screw and a slot. By loosening the set screw, the gear could be
> slid out of the way of the previous gear. This allowed the clockwork to
> disconnect from the motor, thereby reducing the overall drag.
>
> I believe this system was retrofitted for the electric motor but could use
> either at any time.  First, there is still a brake on the flywheel, only
> necessary when using the weights (otherwise, no way to stop it!). and this
> gear that can slide in our out to allow the clock work to engage or not.

    Is the governor purely a drag device, or can it interrupt motor
power for speed control?  The later Phelps printing telegraph (1885 or
so) used purely electrical speed control, cutting a resistor in and
out of circuit, just like governed Teletype motors.
>
> Fun stuff! So far we have the unit generating a pulse when a key is pressed.
> But beyond that, we're still learning!

    You're almost there!  You should get to loopback mode soon.  Then
what?  Build a computer interface so it has something to talk to?
That shouldn't be too hard.  An Arduno, a loop power supply, and some
optoisolators should do it.

						John Nagle