Harold M Hallikainen wrote: > > On Wed, 4 Jul 2001 00:00:50 -0400 Brandon Fosdick > writes: > > > > The Feb 2001 issue of Scientific American has an article that > > answers your > > question. Unfortunately its not accessible from their web site. The > > short answer > > is that its a cost/consumer acceptance problem. Its not yet cheap > > enough to > > compete with conventional lighting in the home market, but its > > making headway in > > commercial and utility applications, namely traffic lights. The > > article also > > says that only 10% of the traffic lights in the US are LED based. > > > > In the past couple months, pretty much all the traffic lights here have > been changed to LED. I kinda wonder what the electronics to run an LED on > 120VAC looks like. I'd expect some sort of boost switcher acting as a > constant current source into a bunch of LEDs in series. Not really very > simple or cheap. In an effort to save electricity, you certainly don't > want to just use a big current limit resistor! > > Harold > The traffic light my friend Al Brown reverse engineered used a capacitor to limit the current. Roman Black was kind enough to put Al's schematic on his web page at: http://centauri.ezy.net.au/~fastvid/tube4w.htm -- Rich > ________________________________________________________________ > 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/tagj. > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads