>Date: Mon, 9 Jul 2001 20:13:51 +0300 >From: "Peter L. Peres" >Subject: Re: [EE]: Bulb Life > Peter L. Peres wrote: >> >> > LED traffic lights >> >> Of course everyone realises that in the event of a major surge or EMP >> all the traffic lights will die. With or without switchers. (LEDs >> don't like reverse biasing). > >> Interesting! Would you suggest a reverse diode across the LED array? > Or better still a big zener or specialty surge diode, this would > protect for both forward and backward surges, considering there should > be a fair series resistance anyway? -Roman -- If you put half of your LED bank in parallel but with reverse polarity (anti-parallel?) to the other half you get full wave power use and no reverse polarity problems. You could also feed a non-anti-parallel system with a full wave bridge rectifier if you want to buy an extra part. Now use a series cap for non-dissipative current limiting and you might have a survivable system (with the bridge system the cap is on an input leg). Looking forward: Alan Shinn Experience the beginnings of microscopy. Make your own replica of one of Antony van Leeuwenhoek's microscopes. visit http://www.mindspring.com/~alshinn/ -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads