On 11/20/16 2:10 PM, Leon wrote:
On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.


I grok!

It all comes down to the power consumed by the devices. 60 Watts of
power has to go somewhere, some into actual photons (light), the rest
into heat. This heat, as far as the LED, an be considered a point
source. Some gets radiated away, the rest gets moved into the
surrounding heat sink *or any other contacting material that conducts heat).

-BR

On 11/20/16 2:06 PM, Leon wrote:
On 11/20/2016 10:29 AM, Markem wrote:
On Sat, 19 Nov 2016 22:54:21 -0600, Leon wrote:

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

The point where the light is emitted from will be hot. Getting rid of
that heat is the secret of semiconductor life. How much current is at
each led will determine how hot it is, well designed leds lights will
not burn you a bad one will. The higher the current at the led the
shorter the life of the led.

In other words you picked the right led lighting system.

Mark


I have to think you have the answer. ;~)

Either way, these are the last set I bought, the previous set was from
LeeValley. These weare about 1/2 price compared to :LeeValley

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


Yep, 48 Watts over 600 LEDs and usually a small resistor for each 3 LEDs
(in series) to knock down the current. These 3528 LEDs have typical
forward voltages of about 3.4 Volts. Three in series (10.2 Volts) means
the resistors dump about 15% of the power as heat (These usually are
driven with a 12 Volt supply).

As far as efficiency, the 3528s are near 100 Lumens per Watt which is
very good, they produce light more efficiently than others (the color
index is rather lousy though).

I usually purchase the parts separately, the LED strip can be had for $10

https://www.amazon.com/SOLMORE-16-4F.../dp/B01335I8E8

and a 12 volt laptop computer power supply for less than that.

Requires a bit of assembly, but perfect for when I make built-in
lighting for a project.

-BR

On 11/20/2016 8:10 PM, krw wrote:
On Sun, 20 Nov 2016 19:42:24 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 5:11 PM, krw wrote:
On Sun, 20 Nov 2016 15:10:07 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.

No, all get hot. How hot is the difference between ones that will
last and ones that won't. Note that "not that hot" may be enough to
burn a finger (100C or above), if you could touch it.


I going to agree that hot is relative. My LED's don't get much more
than room temperature.

Again, the surface may not be much more than room temperature but the
surface temperature of the fixture isn't important to the LEDs
reliability.



;~) I'm just saying that some LED's can remain on 24/7 and not be even
warm to the touch, others will burn you after a few hours.

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

In article ,
says...

On 11/20/16 2:10 PM, Leon wrote:
On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.


I grok!

It all comes down to the power consumed by the devices. 60 Watts of
power has to go somewhere, some into actual photons (light), the rest
into heat. This heat, as far as the LED, an be considered a point
source. Some gets radiated away, the rest gets moved into the
surrounding heat sink *or any other contacting material that conducts heat).

-BR

60 watts is an effing HUGE consumer LED light
bulb though.

The flourescent tube replacements are typically
17 watts for a four foot tube and a replacement
for a 100 watt incandescent typically draws 14.
60 watts would have light output in the same
ballpark as a 400 watt incandescent--this is way
outside the typical "consumer" range.

On 11/21/2016 9:52 AM, Brewster wrote:
On 11/20/16 2:06 PM, Leon wrote:
On 11/20/2016 10:29 AM, Markem wrote:
On Sat, 19 Nov 2016 22:54:21 -0600, Leon wrote:

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

The point where the light is emitted from will be hot. Getting rid of
that heat is the secret of semiconductor life. How much current is at
each led will determine how hot it is, well designed leds lights will
not burn you a bad one will. The higher the current at the led the
shorter the life of the led.

In other words you picked the right led lighting system.

Mark


I have to think you have the answer. ;~)

Either way, these are the last set I bought, the previous set was from
LeeValley. These weare about 1/2 price compared to :LeeValley

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1



Yep, 48 Watts over 600 LEDs and usually a small resistor for each 3 LEDs
(in series) to knock down the current. These 3528 LEDs have typical
forward voltages of about 3.4 Volts. Three in series (10.2 Volts) means
the resistors dump about 15% of the power as heat (These usually are
driven with a 12 Volt supply).

Are some LED's designed to run on 120 volt? I know about the LED lamps
that screw directly into a 120 volt socket, I was under the impression
that the voltage was converted to 12 volt and the heat was generated
from that conversion since the bulb does not get hot so much as the
electronics.



As far as efficiency, the 3528s are near 100 Lumens per Watt which is
very good, they produce light more efficiently than others (the color
index is rather lousy though).

In this last case, the ribbon kit referenced above, the LED's put out a
day light color That was important to my wife as she wanted no color
added when looking at the material on a quilt. But fortunately unless
looking straight into the LED's they appear to be a little yellow and
dim. This is good to prevent seeing spots after looking at the string
of LED's.




I usually purchase the parts separately, the LED strip can be had for $10

https://www.amazon.com/SOLMORE-16-4F.../dp/B01335I8E8


and a 12 volt laptop computer power supply for less than that.

Requires a bit of assembly, but perfect for when I make built-in
lighting for a project.

-BR

I saw a lot of options but this kit had all the connectors, dimmer
switch and remote, power supply for $50. I was good with that
especially since I did not have to worry about compatibility.

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.

On Mon, 21 Nov 2016 09:53:58 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 8:10 PM, krw wrote:
On Sun, 20 Nov 2016 19:42:24 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 5:11 PM, krw wrote:
On Sun, 20 Nov 2016 15:10:07 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.

No, all get hot. How hot is the difference between ones that will
last and ones that won't. Note that "not that hot" may be enough to
burn a finger (100C or above), if you could touch it.


I going to agree that hot is relative. My LED's don't get much more
than room temperature.

Again, the surface may not be much more than room temperature but the
surface temperature of the fixture isn't important to the LEDs
reliability.



;~) I'm just saying that some LED's can remain on 24/7 and not be even
warm to the touch, others will burn you after a few hours.

Hot water can burn you, too. As long as it's in the thermos, you're
safe, though. If you put it in a Styrofoam cup and stick it between
your legs, while driving, bad things are more likely to happen. ;-)

That doesn't mean both coffees aren't hot.

On 11/21/2016 12:07 PM, krw wrote:
On Mon, 21 Nov 2016 09:53:58 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 8:10 PM, krw wrote:
On Sun, 20 Nov 2016 19:42:24 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 5:11 PM, krw wrote:
On Sun, 20 Nov 2016 15:10:07 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.

No, all get hot. How hot is the difference between ones that will
last and ones that won't. Note that "not that hot" may be enough to
burn a finger (100C or above), if you could touch it.


I going to agree that hot is relative. My LED's don't get much more
than room temperature.

Again, the surface may not be much more than room temperature but the
surface temperature of the fixture isn't important to the LEDs
reliability.



;~) I'm just saying that some LED's can remain on 24/7 and not be even
warm to the touch, others will burn you after a few hours.

Hot water can burn you, too. As long as it's in the thermos, you're
safe, though. If you put it in a Styrofoam cup and stick it between
your legs, while driving, bad things are more likely to happen. ;-)

That doesn't mean both coffees aren't hot.


BUT the thermos has a giant separation between the coffee and your hand.
With ribbon LED's you can directly touch the circuitry and LED's that
are attached to the ribbon.


Front to back the LED ribbon is about 3/32" thick that includes the
adhesive backing, ribbon, printed circuit and the LED. There is nothing
keeping you from touching any of those components. LED ribbon is not
totally unlike a printed circuit board except it and the components are
much thinner and very flexible.

http://www.comlite-led.com/img/p/thi...8-thickbox.jpg

The numerous paired gold contacts are about 1" apart, that is where you
cut to length with scissors to attach a pigtail for power.

On Saturday, November 19, 2016 at 10:06:23 PM UTC-5, Martin Eastburn wrote:
Simple - I used to design and test semiconductor material -
I started in the mid 70's and went pro in 1980.

I remember some of the first high speed CMOS HMOS and NMOS
that ran really fast but shorted power to ground in the output
transistors in the process. It seemed ok in theory - but after
millions of cycles the part melted the epoxy off the IC !

All semiconductor heats up. It is conducting current. Current flow
causes vibration heating.

Martin

On 11/19/2016 8:14 PM, DerbyDad03 wrote:
On Saturday, November 19, 2016 at 5:56:49 PM UTC-5, 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.

How do it know?


Sorry, you missed (or never heard) the joke.

There are a number of variations. The safest one is...

A teacher was telling her class about the greatest invention ever: The
Thermos Bottle. "It keeps cold stuff cold and hot stuff hot".

One perplexed student asked her: "How do it know?"

The best ones have a FET in series that acts as a current driver and
delivers the proper value. No resistors - FET and Diode on the tiny
chip. Supply voltage varies and has a useful range - LEDs (Diodes) are
in parallel since the FET is in series with it. The driver then dumps
and maintains say 4-5v and all regulate and shine. One goes out and the
rest are on.

That is the best way but not the cheap way.

Martin

On 11/21/2016 9:52 AM, Brewster wrote:
On 11/20/16 2:06 PM, Leon wrote:
On 11/20/2016 10:29 AM, Markem wrote:
On Sat, 19 Nov 2016 22:54:21 -0600, Leon wrote:

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

The point where the light is emitted from will be hot. Getting rid of
that heat is the secret of semiconductor life. How much current is at
each led will determine how hot it is, well designed leds lights will
not burn you a bad one will. The higher the current at the led the
shorter the life of the led.

In other words you picked the right led lighting system.

Mark


I have to think you have the answer. ;~)

Either way, these are the last set I bought, the previous set was from
LeeValley. These weare about 1/2 price compared to :LeeValley

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1



Yep, 48 Watts over 600 LEDs and usually a small resistor for each 3 LEDs
(in series) to knock down the current. These 3528 LEDs have typical
forward voltages of about 3.4 Volts. Three in series (10.2 Volts) means
the resistors dump about 15% of the power as heat (These usually are
driven with a 12 Volt supply).

As far as efficiency, the 3528s are near 100 Lumens per Watt which is
very good, they produce light more efficiently than others (the color
index is rather lousy though).

I usually purchase the parts separately, the LED strip can be had for $10

https://www.amazon.com/SOLMORE-16-4F.../dp/B01335I8E8


and a 12 volt laptop computer power supply for less than that.

Requires a bit of assembly, but perfect for when I make built-in
lighting for a project.

-BR

On Mon, 21 Nov 2016 13:54:09 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/21/2016 12:07 PM, krw wrote:
On Mon, 21 Nov 2016 09:53:58 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 8:10 PM, krw wrote:
On Sun, 20 Nov 2016 19:42:24 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 5:11 PM, krw wrote:
On Sun, 20 Nov 2016 15:10:07 -0600, Leon lcb11211@swbelldotnet
wrote:

On 11/20/2016 10:02 AM, Brewster wrote:
On 11/19/16 9:35 PM, Leon wrote:



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.

I use a lot of these LED strips in lighting projects, never need any
heat sinks.

Specifically the typical LED used in strips is the "3528" surface mount
device. 4 to 8 Lumens at 0.06 to 0.08 Watts of power. Even the "high
density" strips with 600 of these parts (over 16') dissipates less than
50 Watts. Higher power LEDs (5050s) are only 1/4 Watt each.
It is when you get into the arrays (more common in point source
lights/bulbs) that dissipate 12+ Watts that the heat is palpable (it'll
burn your finger, DAMHIK), Physically they are a "blob" about 3/4"
diameter, mounted on a 1" sq. aluminum plate which is thermally bonded
to whatever heat sink the bulb has.

-BR



Understood but the point I am trying to make is that not all LED
lighting gets hot. I have single bulbs that get hot at the base and
some at best get ever so slightly warm after touching for several
seconds. All of the cool ones are attached to a wood product and stay
on for hundreds/thousands of hours at one time. I get more warmth from
my LCD computer display screen.

No, all get hot. How hot is the difference between ones that will
last and ones that won't. Note that "not that hot" may be enough to
burn a finger (100C or above), if you could touch it.


I going to agree that hot is relative. My LED's don't get much more
than room temperature.

Again, the surface may not be much more than room temperature but the
surface temperature of the fixture isn't important to the LEDs
reliability.



;~) I'm just saying that some LED's can remain on 24/7 and not be even
warm to the touch, others will burn you after a few hours.

Hot water can burn you, too. As long as it's in the thermos, you're
safe, though. If you put it in a Styrofoam cup and stick it between
your legs, while driving, bad things are more likely to happen. ;-)

That doesn't mean both coffees aren't hot.


BUT the thermos has a giant separation between the coffee and your hand.
With ribbon LED's you can directly touch the circuitry and LED's that
are attached to the ribbon.

No, you're not. There is a big hunk of plastic, or three, between
your finger and the active bits.

Front to back the LED ribbon is about 3/32" thick that includes the
adhesive backing, ribbon, printed circuit and the LED. There is nothing
keeping you from touching any of those components. LED ribbon is not
totally unlike a printed circuit board except it and the components are
much thinner and very flexible.

I'm sure it is a printed circuit (AKA "flex circuit"). That doesn't
change the fact that you're *not* touching the LED junction itself.

http://www.comlite-led.com/img/p/thi...8-thickbox.jpg

The numerous paired gold contacts are about 1" apart, that is where you
cut to length with scissors to attach a pigtail for power.
\\

On 11/21/16 9:02 AM, J. Clarke wrote:


60 watts is an effing HUGE consumer LED light
bulb though.

The flourescent tube replacements are typically
17 watts for a four foot tube and a replacement
for a 100 watt incandescent typically draws 14.
60 watts would have light output in the same
ballpark as a 400 watt incandescent--this is way
outside the typical "consumer" range.




Sorry, I was thinking incandescent equivalent when I was intending the
LED equivalent.

-BR

On 11/21/16 9:11 AM, Leon wrote:

Yep, 48 Watts over 600 LEDs and usually a small resistor for each 3 LEDs
(in series) to knock down the current. These 3528 LEDs have typical
forward voltages of about 3.4 Volts. Three in series (10.2 Volts) means
the resistors dump about 15% of the power as heat (These usually are
driven with a 12 Volt supply).

Are some LED's designed to run on 120 volt? I know about the LED lamps
that screw directly into a 120 volt socket, I was under the impression
that the voltage was converted to 12 volt and the heat was generated
from that conversion since the bulb does not get hot so much as the
electronics.



Early LED lamps had a series of standard "gum-drop" style LEDs strung
such that the voltage across each LED was within spec when run directly*
from 120VAC

* There actually is a rectifier bridge to convert the AC to DC.

The first versions had horrible 120 cycle flicker, later versions added
a capacitor to help out. LED Christmas lights were also this way.

LEDs need a constant current source. If fed from a constant voltage
source, small variations in voltage and temperature can produce visible
changes in light output. Most, if not all LED bulbs run from an internal
constant current AC to DC convertor. The LED strips need the small
resistor so they can work with a "standard" 12VDC supply, but they will
(and do) vary in brightness. Most 12VDC supplies are regulated well
enough to avoid noticeable light variations (flicker), but the
temperature variations are still there, just very gradual.



I saw a lot of options but this kit had all the connectors, dimmer
switch and remote, power supply for $50. I was good with that
especially since I did not have to worry about compatibility.

Yes! From a man who has a Domino, I understand 8^)
You wanted a turn-key setup, not a chunk of steel you need to turn into
a chisel so you can chop a mortice. I like saving a few $$ so I can
spend a few extra hours searching for my spool of solder and ordering
new tips for my soldering iron. It's the way I roll 8^)

-BR


-BR

On Thursday, November 17, 2016 at 8:14:54 AM UTC-6, Swingman wrote:


Q: What is the most annoying thing in e-mail?

A: Top-posting.

I doubt it is even close to the most annoying thing in e-mail.

My fluorescent experiences...
Business location #1, 13 years, never changed a tube
Business location #2, 16 years, never changed a tube
Current residence, 20 years, about half have been changed/replaced

As others already replied, duty cycle is a major factor.
The business ones are usually on all day.
Home units are cycled many times a day,
and starting a flurorescent lamp is stressful on the lamp.

I think you're onto something there. For the number of hours a
fluorescent will run in a home, it's probably not worth the more
expensive ballast.

I have the opposite experience.
I got an electronic ballast for a homebrew bedroom lamp
using a Philips PLL tube (thin "U" shape).
The lamp's lasted for many years with no visible weakening.
Instant on, no flicker to the eye or on my camera,
and it seems gentler to the tube than magnetic ballasts.
And it's silent.

-- jeffj