[GreenKeys] Loop driver question

[epvgk at limpoc.com]

On Tue, Apr 23, 2013 at 10:34:33AM -0500, Ken Schwieker wrote:
> 
> 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

That's me :) 

The PS7141E is what I shipped with almost all of the 100+ little demod boards
I was selling on here a while back. They work fine at normal TTY speeds. They 
would not be suitable for "modern" telecom speeds - the turn-on time is hundreds
of microseconds to milliseconds depending on LED drive current. 10 mA gets you
under 1 ms which is sufficient for teletype. under 5mA they get very very slow.
One nice side effect of them being slow is that that limits the creation of
inductive spikes :) 

eric



> 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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