[GreenKeys] inexpensive loop supply transformer wanted

[W2HX]

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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