Hello all, A client of mine had some boards made for LED clusters. Unfortunately the layout is 4 rows of 5 LEDs in parallel with a single resistor for all 5 parallel LEDs. Unfortunately 10 boards had been soldered up before I arrived and realized what was going on. After some discussion and pricing of new circuit boards delivered in 2 days and trial and error with other things the 40 remaining boards are going to be converted to series LEDs with ballast resistor (my spec) by using a dremel tool with grinding wheel to cut all the traces. Dremel saves the day once again! But, the 10 boards already made. A long part of the aforementioned discussion is how long these will last. I did some googling and didn't come up with anything. Here's the specifics: 10 LEDs with 20mA nominal, 30mA absolute max, 50mA pulsed spec. Voltage range is 1.8 to 2.4V, with 2V "typical". 5 in parallel with 100ohm resistor. If run at 30mA or so I'd imagine they'd last forever. Visibly, they are all on about the same amount. And 30mA is within spec. If run at 100mA, whaddya think? (20mA each, if current evenly split). How about 200mA? (40mA each, if current evenly split). Burnout eventually, probably. How long? Does anyone know of longevity curves for LEDs pushed beyond spec? Does it depend soley on manufacturing specifics? And any speculation on what having a bunch in parallel will do? Will one burn out (I assume open-circuit, but is a short circuit possible?) and then the next, etc.? Is it all a crapshoot and depends on the distribution of Vf in the row? Ok many questions. These topics come up often in my EE experience (well, not the many in parallel, but longevity when run beyond spec) since I tend to work with artist types who want a big blinky thing and don't care much about it lasting beyond a few parties. They ask how far it can be pushed, and I just don't know ... All thoughts appreciated! Jesse -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body