I wired a large building with LEDs It worked fine on my bench with my 12V power supply. I took it to the club and wired it to their 12 power supply and it blew some but not all the bulbs. Theye were not the flash burn out that I get when I forget the resister. It took a while. I don't even know what questions to aks. Anyone up to consulting with me here?
I suspect the simplest cause - the club power supply was significantly more than 12 volts.
What value resistors did you use? If the LEDs are rated for 20-25ma, you want to design to something well under that - half would be a good point, so about a 1K resistor. They will be plenty bright for building lights. And that leaves plent of head room so that even if connected to a power supply putting out 24 volts, they wouldn't blow.
Also, did you use 1 resistor per LED, or try wiring some in parallel with a single resistor? Parallel LEDs can lead to a cascade effect since the current changes when one blow out - the rest will all be over current and you get a chain reaction.
Series resistors are OK, if they are all the same. For 12V you can get away with 3 in series, you need to calculate the resistor based on the LED voltage, adding up all 3.
Best is just 1 resistor per LED, then you know it's right. And since bulk resistors are less than a penny each, it's not expensive.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Try this array wizard. It is for dummies like me.
http://led.linear1.org/led.wiz
Brent
"All of the world's problems are the result of the difference between how we think and how the world works."
I have used 1k, 1/4 watt resistors for some years. Allows about 9ma current with plenty of brightness.
Below is a link you might like.
http://www.members.optusnet.com.au/nswmn1/Lights_in_DCC.htm
You can also Google led's series parallel and get lots of link.
I know a few here don't like using google but it has never failed me in many years.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
Were your LEDs wired in series? :ION tried that, all have been removed and replaced with Parallel wiring.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS