[GreenKeys] Teletypes at the Maker Faire

Sat Apr 21 06:27:56 EDT 2018

i am very interested in how you managed to get 45.45 going on the raspi.

On 21-04-18 08:52, Jordan Spencer Cunningham 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:
>       o 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
>       o 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)
>       o 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
>       o 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
>       o 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.
>       o Two relays control 120VAC power to each of the teletype motors
>       o 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.
>       o 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 
> <mailto: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.
> 
> 
> 
> 
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
> 
> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> 

-- 
Met vriendelijke Groet,

Simon Claessen
drukknop.nl