[GreenKeys] Teletypes at the Maker Faire
Jordan Spencer Cunningham
js at cunni.co
Sat Apr 21 22:19:53 EDT 2018
Hi Steve,
Sure thing. I only have written one teleprinter related post thus far, but
I will be writing more as time permits.
The site: https://nerdology.org
Teletype related posts only: https://nerdology.org/teletypes
--Jordan
On Sat, Apr 21, 2018, 4:30 AM Steve Garrison <steve.n4tty at gmail.com> wrote:
> Thanks for the write up about the "guts" of you display. Fantastic work!
>
> You mention your blog, can you post the link? If you have in the past, I
> missed it.
>
> Steve G./N4TTY
> Sent from my iPhone
>
> On Apr 21, 2018, at 2:52 AM, Jordan Spencer Cunningham <js at cunni.co>
> wrote:
>
> Thanks everyone.
>
> There have been some off-list questions about the entire setup,
> particularly about what I have running on that board of electronics between
> the two teletypes. Since several people were curious, I figure I'll share
> with the entire group. Attached is an aerial view of the setup, and below
> is an explanation that may interest or inspire you for your own builds.
> Apologies to those who automatically print out Greenkeys since this is a
> lot of text.
>
> - I didn't have enough time to design and fabricate a permanent
> enclosure for the system, so it's exposed and simply mounted on two pieces
> of wood I had lying around the basement. I plan to design panels and have
> them cut with my brother's CNC machine, after which I will assemble them
> into a box and mount everything inside, but that is a ways out.
> - There is a surface-mount, bakelite-style, round power switch on one
> side that controls power for the entire system. When this is turned on,
> 120VAC power is distributed to a 5VDC power supply and various relays that
> are normally open.
> - The 5VDC power supply gives power to a Raspberry Pi and the main
> electromechanical relay board. This power supply is the smaller silver box.
> - Stacked on top of the Raspberry Pi is a "hat" that distributes the
> GPIO pins into screw terminals for easier wire connections.
> - The Raspberry Pi is programmed using my own software (eventually I
> will release it to the general public for free use, but I have a lot more I
> want to perfect first); currently it is capable of the following:
> - Someone can flick a momentary switch that is connected to the
> Raspberry Pi's GPIO pins, and that will trigger the Pi to turn on the
> requested teletype and current loop via relays. The Pi will thereafter
> listen for input from the teletype so the operator can execute certain
> commands. The teletype and loop automatically turns off if no input is
> received after so much time
> - The operator can execute commands to send an email, send SMS
> messages, and select and print out from presaved ASCII/ITA2/RTTY art (or
> whatever technically correct name you want to call it)
> - The Raspberry Pi checks for new email and SMS messages every 2-3
> seconds (this is configurable); if a new message is detected, it will parse
> it and make it teletype friendly, turn on the appropriate teletype, and
> cause the message to be printed out
> - I will be adding support for ITTY, RSS feeds, direct TCP
> connections, and hopefully i-Telex eventually. I also would like to add
> support for all transmission methods to be optionally encrypted via an OTP
> tape mixer emulation and an Enigma emulation.
> - The Raspberry Pi is connected to two USB <--> 20/60ma loop boards
> that I built after Eric Volpe's design
> - Each Volpe board is connected to a separate current loop, which
> is connected to a separate teletype (very special thanks to Paul at RTTY
> Electronics for having the 1/4-inch plugs and mounts in stock)
> - The Raspberry Pi's GPIO pins also control the electromechanical
> relay board, and I've programmed functions to turn those relays on and off;
> these functions are called by my software as needed to control the physical
> system.
> - Two relays control 120VAC power to each of the teletype motors
> - One relay controls 120VAC power to the 0-150VDC power supply
> (this PSU is currently calibrated to serve 120VDC on the current loops;
> eventually I will also power my M19's tape punch off of it, but I need to
> fix a few things on it first). This is the largest silver box.
> - Two relays control 5VDC power each to trigger two solid state
> relays
> - These two solid state relays control power on each current
> loop so that if only one teletype needs to run during a given time, only
> one loop will be turned on. The Pi could have driven the SSRs directly
> since they'll trigger with as low as 3VDC, but I had my reasons for doing
> it this way with 5VDC instead.
> - Each current loop is equipped with a 10W resistor to limit the
> current and a 62.5ma slow-blow fuse. I chose to add a fuse because at one
> point during construction of the system I accidentally had too much current
> going through the selector magnets of one of my machines, and they started
> to smoke due to the shrinkwrap on the outside of the coils overheating.
> Luckily I cut power before anything catastrophic happened, and the magnets
> still work perfectly fine. I was probably drawing 200-230ma through the
> loop at that time.
> - The plugs that supply power for the teletype motors are also in the
> old surface-mount bakelite style, like the switch.
> - When away from home, an internet connection is supplied from my
> phone connected directly to the Raspberry Pi over USB. Under normal
> circumstances I have it connected via ethernet to my home network.
> - The MacBook you see in the Faire pictures is connected directly to
> the Raspberry Pi over ethernet; I'm simply SSHed into the Raspberry Pi this
> way to show the logs scrolling past. It isn't necessary for the operation
> of the machines-- it's just for show.
> - The wire nuts you see are on one of the loop plugs for my M19; one
> of the cables got severed at some point before I got it. Despite ordering
> old style braided nylon-insulated 18-2 replacement cable, I haven't
> replaced the severed cable yet.
> - The system idles at between 4-5 watts, which equates to around 35-40
> cents a month on average for power pricing around here. I have it running
> all the time and am happy to respond to messages via teletype.
>
> I will eventually write up more about this on my blog including links to
> components I bought for the build, but this is pretty detailed already.
>
> I will probably also add more current loops, though right now I only own
> three teleprinters, and one of them I plan to run off of a Nagle board if I
> can get one.
>
> Hopefully this was helpful to give others ideas or at least provides some
> interesting reading.
>
> --Jordan
>
> On Thu, Apr 19, 2018 at 11:03 PM, Jordan Spencer Cunningham <js at cunni.co>
> wrote:
>
>> Hi all,
>>
>> Thanks for the encouragement and kind words. Showing the teletypes off at
>> the Maker Faire was a success. John Whitney brought his Model 35 and had it
>> connected to a Linux terminal, and I had my 19 printing out SMS and email
>> people sent it whilst my 15 was printing out art the whole day.
>>
>> I have never been to the Maker Faire here in Salt Lake City before, but
>> there were I believe 80-90 total groups showing off various projects of
>> every kind in the State Fairpark Grand Building. I think it's safe to say
>> that the teletypes were one of the more popular exhibits there. I had a
>> pretty good crowd most of the time, and most adults and kids were
>> enthralled with the machines and had a lot of questions. One probably 11
>> year old girl said she just got a new room, and she said a piece of art I
>> printed out at her request depicting Charle's Shulz' "Lucy" from the
>> Peanuts cartoons would be the perfect thing for her wall. John's machine,
>> which was set up just across the way from mine, seemed to attract a lot of
>> people, too.
>>
>> I enjoyed explaining the history of the machines and how they worked
>> electrically and mechanically to people interested in them, which were
>> many. I had a mechanical engineer and an electrical engineer both exclaim
>> that they'd never seen anything so amazingly engineered.
>>
>> There were maybe three or four people who came up with big smiles on
>> their faces and talked about the old days when they or their parents used
>> to work with teleprinter machines back in the 70s. It was fun to see those
>> memories reawakened.
>>
>> A lot of people thought I had retrofitted typewriters. They were excited
>> to hear that the teletypes were completely original designs dating from
>> 1930, operating exactly as they did back then.
>>
>> I was invited to bring the machines to the Thanksgiving Point Maker Faire
>> in September (that's around 20-30 miles south of Salt Lake City), and there
>> were some other groups that wanted me to bring them by.
>>
>> It was a fun day and one I'd love repeating again.
>>
>> I was up until 6:00 AM before the faire with a long night of polishing up
>> some finishing touches, printing out extra art to give away, testing, and
>> fixing a couple of bugs in both the software and the machines that I
>> discovered. There was a heart-stopping moment when I thought I had somehow
>> destroyed my last remaining optoisolators on the two boards and thought I'd
>> be completely unable to operate since I couldn't get any replacement
>> components in time. Luckily it turned out to be a really weird hardware bug
>> I have not had time to fully trace that was simply solved by reversing the
>> loop polarity (the boards are supposed to be polarity insensitive and were
>> working fine in the opposite polarity until that moment). I had a few
>> moments like this where I grumbled things like, "Why can't I just be like
>> everyone else and do something easy like play video games?!" However, the
>> end result is well worth the moments of frustration.
>>
>> The machines ran incredibly well and are a monument to how well the last
>> person who owned them took care of them. He became silent key in the 70s,
>> and the machines sat idle in his basement for about 40 years until I had
>> them shipped across the country to me last year. I had oiled and greased
>> the major parts, replaced a couple of missing parts, tightened some nuts
>> and bolts, and did some modest cleaning, but there is still plenty I want
>> to do to clean and restore them. Despite that, both machines ran incredibly
>> well for hours and brought enjoyment and wonder to hundreds of visitors.
>>
>> Attached are some photos. I meant to have more, but I forgot to bring my
>> camera. My phone was plugged into the Raspberry Pi to supply the internet
>> connection, so I couldn't take it more than a couple feet away for
>> pictures. Most pictures were taken by my wife.
>>
>>
> <20180420_201740.jpg>
>
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