Quoting Yigit Turgut : > I am just wondering ; I have some TSTS7201 from Vishay-Telefunken and > these devices do not have any kind of polarity. Pins are at same > length and there is nothing mentioning about polarity in the > datasheet. What kind of diodes are you using for tx ? I forget exactly as I can't find my order and I don't have them to =20 hand, but they were Osram and most likely something similar to SFH4550. David --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .