http://groups.yahoo.com/group/Optical_DX/ Australian Optical DX Group Wed, 27 Jan 2010 07:35:47 GMT Tim Toast http://groups.yahoo.com/group/Optical_DX/message/442 http://groups.yahoo.com/group/Optical_DX/message/442 With all the blue and UV led's out there, i bet a good match can be found for the 3371A nitrogen line. Relatively simple home built nitrogen lasers that work Wed, 20 Jan 2010 21:33:59 GMT inverse http://groups.yahoo.com/group/Optical_DX/message/441 http://groups.yahoo.com/group/Optical_DX/message/441 ... looks promising, sparks' emission spectra in open air peaks at 337nm, the superradiant nitrogen line. A significant portion of the energy could be detected Wed, 20 Jan 2010 20:10:27 GMT Garnier Yves http://groups.yahoo.com/group/Optical_DX/message/440 http://groups.yahoo.com/group/Optical_DX/message/440 Tim I noticed an error in my last mail: I want to write : "Unfortunately it seems that a LED diode used as photodetector receives a wavelenght slightly shorter Tue, 19 Jan 2010 22:30:48 GMT Garnier Yves http://groups.yahoo.com/group/Optical_DX/message/439 http://groups.yahoo.com/group/Optical_DX/message/439 Tim Unfortunately it seems that a LED diode used as photodetector receives a frequency slightly lower than its own transmission frequency. To receive a Tue, 19 Jan 2010 21:15:50 GMT Tim Toast http://groups.yahoo.com/group/Optical_DX/message/438 http://groups.yahoo.com/group/Optical_DX/message/438 Hi Yves, That would certainly simplify transceivers and alignment if you could use the same LED to receive. That would put an end to the full-duplex though. Sun, 10 Jan 2010 06:45:21 GMT Andrew Russell http://groups.yahoo.com/group/Optical_DX/message/437 http://groups.yahoo.com/group/Optical_DX/message/437 Yves It sound like there might be a negative resistance region there. Andrew ... _________________________________________________________________ View photos Sat, 09 Jan 2010 18:13:08 GMT Garnier Yves http://groups.yahoo.com/group/Optical_DX/message/436 http://groups.yahoo.com/group/Optical_DX/message/436 Hi all Thank you for these details about LED used as photo detectors. I just did some tests with three super bright red LEDs GL0ZJ042B0S from SHARP. I select Sat, 09 Jan 2010 03:21:33 GMT Paul Edwards http://groups.yahoo.com/group/Optical_DX/message/435 http://groups.yahoo.com/group/Optical_DX/message/435 I remember seeing LEDs used as wavelength selective detectors in a sun photometer about 10 years ago. How about NIR 850/900 nm GaAs & 1550 nm InGaAs/InP LED Fri, 08 Jan 2010 06:11:03 GMT Andrew Russell http://groups.yahoo.com/group/Optical_DX/message/434 http://groups.yahoo.com/group/Optical_DX/message/434 Cool! LEDs have been used as insensitive but frequency selective photodetectors in the past. One app I have seen is a yellow LED for measuring solar Thu, 07 Jan 2010 14:27:40 GMT Tom Becker http://groups.yahoo.com/group/Optical_DX/message/433 http://groups.yahoo.com/group/Optical_DX/message/433 Optically discharging a reverse-biased LED has been around for some time. Using one as an APD, though, is intriguing. Thu, 07 Jan 2010 14:12:47 GMT rds_6 http://groups.yahoo.com/group/Optical_DX/message/432 http://groups.yahoo.com/group/Optical_DX/message/432 The ez430 USB-based evaluation board for the TI MSP430 microcontroller has sample software for it that uses the on-board LED as both a photodetector and a LED. Wed, 06 Jan 2010 22:05:14 GMT Garnier Yves http://groups.yahoo.com/group/Optical_DX/message/431 http://groups.yahoo.com/group/Optical_DX/message/431 LEDs can sometimes be used like photodiodes with a selective response just under their nominal light frequency BW. Now it is found that the photocurrent can be Sun, 15 Nov 2009 07:18:24 GMT vk7tangledwhiskers http://groups.yahoo.com/group/Optical_DX/message/430 http://groups.yahoo.com/group/Optical_DX/message/430 Greetings All, The report of the 288km NLOS one way cloudbounce contact across Bass Strait from VK7 to VK3 has now been posted to the REAST website and can be Wed, 28 Oct 2009 12:27:06 GMT Robo L http://groups.yahoo.com/group/Optical_DX/message/429 http://groups.yahoo.com/group/Optical_DX/message/429 Congratulations boys! Good works! Justin, please downlaod and fill my form for publish world record on my pages Please edit the form with Notpad (or similiar) Wed, 28 Oct 2009 11:55:07 GMT vk7tangledwhiskers http://groups.yahoo.com/group/Optical_DX/message/428 http://groups.yahoo.com/group/Optical_DX/message/428 On the night of October 27th 2009, Rex VK7MO and Joe VK7JG assisted by Paul VK7KPG set a new one way NLOS Optical record of 288km across Bass Strait using red