[GreenKeys] black box loop - 232 interface question

[wa2hwj at att.net]

Gil is 100% correct. I found one of those boxes some time ago and discovered
that it would not work with a HV loop (it now doesn't work at all!).
It is suited for a Model 32/33 type of LV loop circuit (no more than 30VDC).
There is a high-voltage model, but they haven't shown up on Ebay.
I believe a reed relay in series with the LV loop would key a
HV loop, as long as the relay's contacts are protected with
a snubber circuit. Put the TTY's keyboard signal in series with
the LV loop and relay and it will provide a keyboard signal to the
RS232 side of the box and also print on the printer through the relay. 

73,
Jack K0TTY

NNNN

-------------- Original message from gil smith <gil at baudot.net>: -------------- 


> Those boxes are only designed for low-voltage loops (up to about 30V 
> IIRC)-- don't hook one to a 28 and high-volt loop supply. 
> 
> I think they also had an option for an internal supply, but it was 
> something like 18V at 20-mA -- fine for a 33, but maybe not what you need. 
> 
> gil 
> 
> 
> At 05:26 PM 6/12/2008, you wrote: 
> >Did anyone come up with a schematic for those boxes that were on ebay? 
> > 
> > 
> > 
> >I got a couple of the boxes and they look good just need to figure out the 
> >details so I can connect it up to my model 28. 
> > 
> > 
> > 
> >Thanks, Stan AK0B 
> > 
> > 
> > 
> > 
> > 
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> 
> 
> 
> Vaux Electronics, Inc. 
> 480-354-5556 
> (fax: 480-354-5558) 
> www.vauxelectronics.com 
> 
> 
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