[GreenKeys] A reliable current-loop-to-RS232 converter

[Jeffrey D Angus]

On 8/13/2015 9:15 PM, Gil Smith wrote:
> Shhesh.  Really nothing to go on unless someone recognizes this unit.
> Likely some Chinese thing in many stores.  I would open it up and
> trace out the schematic, but that is often not an easy task, especially
> if it has more than two layers (though I doubt it does).
>
> Does this look familiar to anybody?
This one in particular no, but I've seen similar.

The problem is NONE of these are designed to work with an inductive
load. They are designed to run either a 20 or 60 mA current loop using
a matching converter at both ends of the cable.

The "give away" on any of these converters is the "Will work up to 19K
baud." That and being powered off a USB cable or external +5v supply.

Similar problems with the "Black Box Inc." current loop converters."
They were designed with a maximum loop voltage of around 65 vdc,
NOT 120 vdc. And they get unhappy REALLY fast driving a 4 Hy magnet
with huge spikes from the switching.





-- 
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

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