At 12:22 AM 6/12/02 -0700, Rick Mann wrote: >Anyone out there know how to "properly" interface coax SPDIF to TTL? Here's >what I tried: > >SPDIF coax input to Pulse Eng isolation txfmr. Txfmr terminated with 75 ohm >resistor. Txfmr signal through 0.01 microfarad DC blocking cap, into + input >of a National RS-422 receiver. - input of receiver thought 0.01 cap to >ground. > >Now, as it happens, the TTL out from the receiver only gives a clean signal >if I remove the terminating resistor. Furthermore, the open-loop signal >coming from the SPDIF source is 1 V p-p, rather than the 2 V I would have >expected. If I put in the 75-ohm terminator, too much power is consumed by >it, and it won't trigger the receiver. Yeah - use a line receiver after the isolation transformer. Remember - SPDIF is only 0.5V peak, not 5V. I use a RS-422 receiver (26c32) in my stuff - a RS-485 transceiver strapped in receive mode will work nicely as well. The terminate resistor is a good idea just to stop ringing if you are at the end of a long cable. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics