Romilly's HART® and Fieldbus Message Board
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Direct coupling of HART modem
Message posted by Oliver Sedlacek ( : 81.86.194.251) on 04 April 2005 at 15:26:18.
I've been tasked with designing a HART device and I would like to avoid the size and expense of a coupling transformer. I've come up with a few possible solutions, but I was wondering if anyone else was using direct coupling. My biggest problem is rejecting interference when the transmitter is disconnected, because it seems I have to tolerate 8V peak-to-peak interference at 25Hz without imposing a low impedance on the receive signal.
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