[GreenKeys] inexpensive loop supply transformer wanted

[COURYHOUSE at aol.com]

I recommend  a   museum  controller....    one   function  would  also 
include  TTY   control.... 
 
 I recommended  it as  project  to Gil    quite  a while  back actually...  
now that he  is   looking  for  new  avenues to apply  his  design talent  
to this  would  be a good one  for  him!
 
 The  thing  could  control i/o   music,  video, electronic sineage   It  
would be a good niche   market  product...  also interact   with visitors... 
monitor  security of  displays... and   wait! there is  more!!   good  
stuff!  the  control of a teletype  would   actually be a  small part  of this   
thing. A  serial  device  is a serial  device...  you just provide the   
output interface levels  per request.
 
Ed Sharpe   archivist for SMECC  
 
 
In a message dated 12/29/2013 5:15:08 P.M. Mountain Standard Time,  
w2hx at w2hx.com writes:

I've  always thought about building a little box (maybe now a raspberry pi 
would do  the trick) and write a telnet server on it. The rasp-pi could then 
drive/read  a 60ma loop. The rasp-pi could do the ASCII baudot conversion. 
I have an  aversion to USB. Seems everything needs it's own driver. I like 
simple sockets  and TCP/ip

Maybe a project for Gil!
73 Eugene


73 Eugene  W2HX

-----Original Message-----  
From: Ed Sharpe [couryhouse at aol.com]
Received: Wednesday,  25 Dec 2013, 8:01pm
To: Ken Schwieker [ksweek at mindspring.com];  GreenKeys at mailman.qth.net 
[GreenKeys at mailman.qth.net]
Subject: Re:  [GreenKeys] inexpensive loop supply transformer wanted

Some one needs to get with it and build a group for sale at a reasonable  
price... usb in... 20 & 60 mil out

Ken Schwieker  <ksweek at mindspring.com> wrote:
>If you don't want the approx 160+  volt loop supply with some of the 
>problems associated with that high  of a supply there are inexpensive 
>lower voltage transformers  available.
>
>Here is the info I posted about this particular  transformer some time 
>ago. These transformers look to be well made and  most likely in US.
>
>Just a heads up on a source of very  reasonably priced transformers 
>suitable for loop supplies.
>Can  be used to construct a supply with a somewhat lower and safer 
>voltage  than the usual 140 volt or higher ones.
>Did some tests, primary at 120  v;
>74 v ac no load
>70 v ac with 100 ohm load (700 ma)
>One  hour with 100 ohm load connecter, transformer temp 110 F (ambient  
>about 70 F).
>Size, 3" x 2 1/2" x 2 1/2" high not counting  chassis mounting tabs. 
>Mounting holes 3 1/2" between  centers.
>Only two terminals on the bottom (pri) and three on the top  (center 
>tapped secondary) are used.
>I purchased 3 and the total  was around $25 including shipping
>
>http://www.apexelectronic.com/TR5-W-26
>
>Ken  S
>
> >At 11:56 AM 12/20/2013, you wrote:
>I'm working on  a small project to have a Single Board Computer such 
>as a Raspberry Pi  or Arduino drive my TTYs (Model 15 at 45 WPM and a 
>28 RO at 75 WPM)  with some canned messages from memory. As part of 
>that effort I'd it  to have it's own loop supply (120VAC to 120VAC 
>isolation transformer,  bridge rectifier, filter cap, 2800 ohm 20 watt 
>limiting resistor).  Does anyone have suggestions on where I might 
>find a low cost  isolation transformer for this purpose?
>
> >Paul Newland,  ad7i
>
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--  
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--  
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