[GreenKeys] Loop driver question

[Ken Schwieker]

I am in the process of building a few loop supplies using the $5 loop 
transformers mentioned in a previous post. DC output is right at 100 
volts which for me is ideal compared to a higher loop voltage 
(sometimes in the 160+ volt range). I believe 100 volts is high 
enough voltage for a reasonably fast current rise time, high enough 
to conduct through an oil film on any contacts as well as the lower 
voltage works out to significantly less heat generation by the loop 
current limiting resistor and the lower voltage poses less of a shock hazard.

Wanted to find out if anyone has had experience with the CEL 
PS7141E-1A-A optocoupler used as a loop driver. Found it in a list on 
the following website.
http://heepy.net/mediawiki/index.php/Optocouplers_for_teletype_current_loop 
Do not know who produced this website but thanks. Found that the 
PS7141 is available from Mouser at $1.56 each. Some of the others 
optocouplers are somewhat more difficult to source including one that 
was a special order with a 100 min.  I plan to build an external loop 
driver for a Tempest Dovetron but will have to see if the Dovetron 
can output around the 10 ma necessary for the input to this optocoupler.

Any inputs appreciated.

Ken S

















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