On 11/21/2016 9:59 AM, Brewster wrote:
On 11/20/16 1:57 PM, Leon wrote:
On 11/20/2016 7:19 AM, krw wrote:
On Sat, 19 Nov 2016 22:54:21 -0600, Leon wrote:

krw wrote:
On Sat, 19 Nov 2016 22:35:52 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/19/2016 4:56 PM, krw wrote:
On Sat, 19 Nov 2016 09:47:06 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/19/2016 9:33 AM, Brewster wrote:
On 11/13/16 8:43 PM, krw wrote:


It's not about the tube getting hot. It's about the
semiconductor
junction heating. Without a *really* good heatsink, they will
overheat. Most are *way* under designed.



An old rule for electronics is 10 sq. inches of heat sink surface
(exposed to room temp) for every Watt of power. Many of the
"flood"
style bulbs which don't have the room for this get by with
thermal mass.
They don't saturate the heat sink for 1-2 hours, giving you time
to get
your lighting task complete before damage begins. This is the
bane of
the Edison style bulb for LEDs. Tubes have the surface area
going for
them, but the cheaper tubes find a way to skimp on the aluminum to
mitigate any advantages 8^)

-BR



There seems to be a lot of confusion concerning LED's and their
heat out
put. I have LED lamps that replaced incandescence bulbs and the
light
is cool but the part that converts to the proper voltage
generates heat.

I also have probably 20' of high density ribbon LED lights that
run on
12 volt and they do not even get warm.

You can bet that the semiconductor junctions are getting warm. The
fact that the surface isn't may also mean that the semiconductors
inside are getting downright toasty. My thermos mug doesn't get
warm
on the outside, even when filled with very hot coffee.



I cab pinch the ribbon LED beteen my thumb and my finger.
Nothing. We
leace these lamps on in our kitchen 24/7 and there is not heat what
so ever.

But you can't touch the junction, which is what counts.


Define junction on ribbon LED lighting. No where on the ribbon gets
remotely warm.

The part that creates the light. I don't know what sort of ribbon
light this is but if it's designed for illumination, you can bet the
junction is getting quite hot. If it's just for looks, it may be much
lower power.



Well, not for looks, these light up our kitchen counter tops and the
length of my wife's long arm machine. Lighting is critical on the long
arm machine. But there are hundreds of LED's on that ribbon, IIRC 3 per
inch along 11 feet.


I have them as under cabinet lights too, they are excellent!

Spreading out the light is what they excel at. Lee Valley (and others)
sell housings for them that provide a great way to mount them and have
diffusers in clear, translucent and an "opal". The diffuser makes them
look like a continuous bar of light instead of many little dots,
important if you have shiny counters (though they do cut the light
output quiet a bit).

-BR


I thought about the diffuses, but opted for sticking directly to the
bottoms of the upper cabinets. We have shiny granite counter tops you
you do see each individual LED in the reflection but is is not
distracting and It seems you have to be in just the right position to
notice the spots on the counter top. Any thing 3' out and you don't see
them at all. Closer you see them but they are simply spots that do not
distract.