On Thu, 8 Nov 2001 13:17:11 -0500 Douglas Butler writes: > Manchester encoding is designed to go through transformers (no DC > component). If you are going to build a clamp circuit, how about > building a PIC NRZ to Manchester converter? > > On the other hand I sometimes capacitively couple TTL lines to > prevent > disaster when someone confuses +12V and data. Use a pull resistor > to > the quiescent state and make sure the cap is big enough for the > longest > string of 0's or 1's. > Due to standards, I've gotta transmit the data as NRZ. The data is continuous 250 kbps NRZ (standard UART output of 8N2). There will definitely be some DC component, but if the transformer "throws that out" but maintains the peak to peak relationship on the secondary, it seems that I could just capacitor couple into the RX input of a PIC and the clamp diodes would DC restore it. I might also want to add a DC blocking capacitor on the primary of the transformer to remove the DC from the primary, avoiding core saturation. I'm just playing around with ideas for receiving DMX on an isolated receiver without having to do the typical biz of having a receiver chip drive an opto (which requires an isolated power supply to drive the receiver chip). It SEEMS that I could just have a relatively high Z transformer do a 1:1 voltage conversion, AC couple into the PIC and get DC restoration. Perhaps I'll have to build it and play with it a bit to see why it doesn't work! Harold FCC Rules Online at http://hallikainen.com/FccRules Lighting control for theatre and television at http://www.dovesystems.com ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. -- 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