Interesting story of Blue LEDs

I would give a lot more money for an LED bulb that lasts. I seem to replace them (all types) on a very unregular basis. The one that replaced last in my office lasted 2 days. Now that is a record to be sure, but others don't last for more than maybe 2 months.
 
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I would give a lot more money for an LED bulb that lasts. I seem to replace them (all types) on a very unregular basis. The one that replaced last in my office lasted 2 days. Now that is a record to be sure, but others don't last for more than maybe 2 months.

Don't buy the cheapest ones, I like CREE. I bought several of the early CREE 5000K bulbs years ago, and they still work fine.
But maybe your AC line is too high.
 
The feed for the common line serving my immediate neighborhood was a pole transformer about 3-4 houses down, with the 1100V feed running along the property line. I could just see the pole transformer from my back step. The power company then decided to move the transformer right to the corner of my property, where I can stare right back up the feed line to the pole transformer from my back window (first dibs!). The line voltage went up to around 125V (until they turned it down a few clicks) and I would get random "blue screens of death" until I invested in a UPS that had some heavy surge protection tucked inside. This was in the days before computer power supplies came with a PFC front end - they all used a cheapo bipolar half-bridge topology with a voltage doubler input and a manual 115/230V selector switch. The newer computer supplies use a 2-switch forward topology with a PFC front end and saturable reactors to generate the 3.3V output from the main 5V winding.
The power goes out quite a bit more often in my new downtown digs than it did at my old abode - maybe it's the aging infrastructure in the San Jose downtown area. A few years ago, we had a underground vault transformer blow up, and it took down quite a large hunk of downtown, on one of those hot, airless summer nights. Without any juice, you couldn't even run a table fan to get relief from the heat, unless it was one of those battery-operated dinguses.
 
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Well, it appears that anyone can make a crappy product. The two frosted light bulbs that I have recently changed out (both of them in the last 5 days) were both incandescent, Westinghouse brand, made in China. I apologize for the assumption that all LED bulbs are crap.
let me add a small detail about bulbs and electrical products in general. Most of them say 120 volts for a rating, which I understand can be fudged a little bit. Here is the wisdom of the ages, they used to make 'commercial' light bulbs rated at >130 volts<. Yes, they lasted a hell of a lot longer.

wrenchone, A few years ago, we had the same type of little disaster at the local substation. Hmmm boy, a whole of people showed for that one. Fire trucks, cops, ambulances, you name it. They got things back up on two legs instead of three and told everybody to power down what they could.
 
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I just measured my line voltage at the plug, and it is 124VAC - a bit on the high side still. Old legacy tube amplifiers from the 50s will likely need a bucking transformer to quiet things down a bit, as they were designed when the std line voltage was 110-115 VAC. A 12V filament XFMR with the usual 1500V isolation would do the trick.

I'm reconditioning an old Scott 399 receiver for a friend of mine - I think I will ask her to measure the line voltage where she lives, to see if a bucking transformer is in order. She will also get an IEC-style connector for a 3-wire cord, with the safety ground securely nailed to the chassis (hack, hack, file, file...).
 
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122 VAC here pretty regular.
Ok, so this is really going to date me. Paul Harvey remember him?) once endorsed a product that you put into a lamp socket that make your bulbs last forever, so to speak. Yes, of course it was nothing more than a flat resistor made to fit in that space. Man did it ever get hot. Now you know the rest of the story.
 
Halogen incandescent lamps last forever IME when they are run hot but slightly below rated voltage and, more importantly, with soft-start.

Those nice looking "LED-String" clear bulbs randomly failed all the time for me. I've completely stopped using them.
 
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music soothes the savage beast
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Here is my story with bright blue leds...
I had sony tabletop clock-radio, the ubiquituos model from 80ties, like in every hotel room. Had nice red display, which adjusted display brightness for daylight. Nice AM/FM radio with small fullrange. Worked for decades. The case, originally white, was slowly turning creamy, later yellow. Still worked, but was ugly.
So i decided to replace it. Bought something similar, table clock with radio. Had blue-white display covered with cloth. Looked ok in the store, actually sounded rather good.
Problem was the display. While nice at daylight, awfully bright at night. There was no way to adjust it. I could not sleep next to that thing. Even if i turned that thing away, it was illuminating whole room. What's the point of having clock, when you do not see the display. Ripped the cloth off and experimented with markers, still way too bright. Ended up placing red insulation tape over the display. Worked for a while, was ugly, later trashed it. End of story.

I have some schiit stuff, with bright white/blue led as on indicator, painted over, its ok. One day i will replace it with proper red led.
 
Intensity of light emitted by superbright blue/white LED can be easily adjusted by limiting the current flowing through it.
100µA (0.1mA) is enough for pleasant, undisturbing glow.
It means 18k resistor in series with blue/white LED on 5V supply or 56k when 9V supply is used.
Easy fix.
 
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I should be addressing this today, since I have a newly built preamp with 5 LED indicators! Only one at a time will be on, depending on the selection made. Last time around, I used silver paint and a Q-tip, but that is not the best answer here. One builder incorporated a trimmer pot to address this, but I am wondering if I picked all 5 LED's with the same brightness. I have done numerous experiments besides adjusting the series resistor, just because, and one of the coolest ideas was placing a small ball bearing right in front of the LED, blocking the direct light, but allowing just a little around the perimeter. Since it is a PITA to do with just one, it inevitably will be the method that I pick. How else are you going to stand out from the crowd?
 
I’ve been using red and amber in my DIY builds for years, but mainly because I’m a sucker for the 10+ pricing at Mouser.

Think I may try blue on the iron Pre in honor of this thread, with the brightness dialed down a bit. We’ll see how it goes.

Ive had Schiit DACs for years now and their lights can be a bit bright, but they've also worked well enough that I dont give them much thought...only focusing on amps and pres. That has to be a good thing :)
 
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