At 06:16 PM 11/19/02 +0000, you wrote:
>A really good way of doing this is to use the "linear" opto-couplers from
>H-P (or whatever they're called this week).  The HCNR200 application
>datasheet has excellent circuits for 4 - 20 mA TX and RX.  The only omission
>in these designs are the RFI suppression and decoupling capacitors that
>you'll find necessary in the "real world".
>
>The accuracy and linearity possible with these devices is remarkable.

Why would accuracy and linearity be important in a digital circuit?

These are the same kind of circuits that used to directly energize a
solenoid in the old Teletype machines, NOT process control type
analog current loops.


Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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