[GreenKeys] inexpensive loop supply transformer wanted

[Ken Schwieker]

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