Tesla

That must be why every datasheet expresses thermal resistance as "C/W". ;-)

The proper ones spec K/w.

The anal ones, perhaps. The fact is that it's a distinction without a difference.

If this is a single LED, it must be rated for 3 A maximum ? Now look carefully at which current the 25000 hours is specified. My guess is either 1 A or 2A.

The phosphor output drops quite quickly over time due to the intense blue LED radiation. This degradation determines those claimed life times. At max rated LED current, the output drops after a few hundred or a thousand hours. To get a decent life time, you should run the LED at 1/2 or even 1/3 maximum rated current. After the "lifetime" the LED still emits blue light, but the conversion to white light is very low.

This helps keeping the junction temperature down and helps extend the lifetime of the semiconductor. It doesn't help much about the phosphor lifetime.

On Mon, 17 Aug 2015 19:54:28 -0400, krw Gave us:

The scale must be declared as it cannot be assumed in any discussion circle, child.

On Mon, 17 Aug 2015 17:46:46 -0700, John Larkin Gave us:

It matters not. In ANY and EVERY case, the scale needs to be declared.

Think about failed Mars mission craft if you need an example as to why.

I thought you were a Linux user - these sorts of symbols are /so/ much easier to type on Linux rather than Windows. Details vary according to

shift-altgr-0.

Degrees Celsius is perfectly acceptable as an engineering term for relative temperatures, since a difference of one degree Celsius is the same as one Kelvin. For absolute temperatures, Kelvin is the only scale suitable for engineering.

K is kelvin which is the same scale but a different offset.

C is coulomb.

linux arbitrary codepoint entry is a mess. on the console left-alt works much like in windows, right-alt used to do hex entry but that's been dropped, and it's base 10 too now. And in gui it's all different.

That's me--I'm unconventional.

Cheers, James Arthur

They all seem to use arrays of 1/2w LEDs. It's amazing how cheap they've gotten. These bulbs very likely have a couple large electrolytics too, which limits the service life. Heatsinking makes those a lot happier.

This is a related, earlier version of the same bulb.

(Mine is newer, 5000K instead of 2700K, non-dimmable, and more efficient--

Cheers, James Arthur

That is not my experience - it all seems to work fine for me. However, I can't say I've had need of entering any unusual characters from the plain console (as distinct from a terminal window in X, where the keyboard is exactly the same as everywhere else in X). I typically only see a plain console during installation or major "surgery" - my Linux systems are either headless or have X.

And of course with Linux, things are always configurable - with different distros having different defaults. You may have to enable a compose key before you can use it.

least under normal conditions.

This should be on John's interview question list- if a resistor heats

--sp

The answer should be instant. 50 * 9/5 is 90.

Huh? How does that work? Absolute temperature and relative temperature are either specified or taken from context. The symbols have nothing to do with it.

I don't get that distinction at all.

Oh crap. I wasn't looking at the numbers, just the representation.

That's why all junction temperatures are specified as C, right? Everyone is wrong but you and JL?

You're AlwaysWrong. The "degrees" (or the little circle) is redundant for C or K (not so for F or R). IOW, "degrees C" is wrong, AlwaysWrong.