How much is 'less than 5mW' ?

[StuM]

Originally Posted by SteveSails

I question the 5mW rating, LEDs are efficient but not that efficient. Sure the specs didn't say 5mA or 5 milli Amps? Even an indicator LED, not bright enough to read by, would draw a couple of milli amps and even 1mA at 12V would be 12mW (.001A x 12V = .012W).
The seller may not be trying to deceive, often specs get lost in the translation. Ohm's law and the power formula are good things to memorize, helps to raise ???? when something seems too good to be true.

Any link to the specs? We can help make sense of it for you.

Yep, <5mW is improbable to say the least!

The smallest single LED 12V bulbs that I've seen are around 250mW, so even <5 mA is not feasible (250mW @ 12V = 20mA)

[topmast]

Just saw an ad for 48volt battery drill. They said the competetions is only 18.5 volts so theirs have more than twice the power.Ignorance seems to work good ,huh?

[StuM]

Originally Posted by topmast

Just saw an ad for 48volt battery drill. They said the competetions is only 18.5 volts so theirs have more than twice the power.Ignorance seems to work good ,huh?

Not more powerful in the strictly scientific/engineering sense, but they are certainly more forceful and deliver a lot more torque.

In layman's terms of "ability to act or produce an effect", it's not that bad a word to use.

[newhaul]

Originally Posted by topmast

Just saw an ad for 48volt battery drill. They said the competetions is only 18.5 volts so theirs have more than twice the power.Ignorance seems to work good ,huh?

More powerful in this case means more torque to do the job with

[transmitterdan]

An LED will make usable light at 5mA and about 1.2V so that is only 6mW. If you overdrive the LED at higher current but very narrow pulse widths the efficiency goes up even more. So I can believe it draws 5mW.

But be aware that it probably generates a little radio interference. Not a lot at that low power though.

[newhaul]

Led pointer lazers that use a single AAA battery and are rated at 5mw
I have a red flashing bike light that has 4 5mw led bulbs in it and you can.read a.book by it ( uses 2.AA batteries)

[StuM]

Originally Posted by transmitterdan

An LED will make usable light at 5mA and about 1.2V so that is only 6mW. If you overdrive the LED at higher current but very narrow pulse widths the efficiency goes up even more. So I can believe it draws 5mW.

But be aware that it probably generates a little radio interference. Not a lot at that low power though.

Guess that depends on your definition of "usable". For "map reading"?

And do you know of any 12V LED bulbs that draw that little? All the little 12V car etc map lights that I can find come in at around 1W

Typical ones: http://www.narva.com.au/products/bro...reading-lights

Do you really think that a light with 1/200th of their power consumption is feasible?

[StuM]

Originally Posted by newhaul

Led pointer lazers that use a single AAA battery and are rated at 5mw

That's the power output , not the power demand.
Your typical 5mW green pointer with 2 x AAA cells will use about 300 mA @ 3V = 900mW.

See here for example: Core Series - 5mW Green Laser Pointer | Wicked Lasers

I have a red flashing bike light that has 4 5mw led bulbs in it and you can.read a.book by it ( uses 2.AA batteries)

5mW bulbs? I sincerely doubt that for all the reasons stated above..
The best Crees get about 300 lumens per Watt. So those bulbs would max out at about 1.5 lumens for a total of 6 lumens.

That's the same output as a single 3528 SMD in one of those strip lights that people put up under their biminis. (that's the smallest and dimmest SMD).

[topmast]

:faceplant

[topmast]

[newhaul]

https://jet.com/product/detail/aeb33...FYKJfgodWGAAfA
1lumen solar pathway lights we get them here at walmart for a buck each.

[meatservo]

Originally Posted by MarkJ

For a reading lamp?

Bloody useless for Penthouse.



.

You need to find more seedy websites...


meatservo

[transmitterdan]

Originally Posted by StuM

Guess that depends on your definition of "usable". For "map reading"?

And do you know of any 12V LED bulbs that draw that little? All the little 12V car etc map lights that I can find come in at around 1W

Typical ones: http://www.narva.com.au/products/bro...reading-lights

Do you really think that a light with 1/200th of their power consumption is feasible?

There is no such thing as a 12V LED "bulb". The driver circuitry converts 12V supply to the voltage/current required by the LED chip. Some drivers are more efficient than others.

Yes, I think it is feasible to get some usable light with 5mW input power from a high efficiency LED. I don't know if this particular one is truly 5mW or not. I'm just saying it is feasible. The amount of power in the visible light emitted by a single LED is a lot less than 5mW.

[TrentePieds]

Can one of you engineer-types give us a swift and pithy intro to the concept of the "lumen"? Its definition, its relationship to the "watt", the fact that light intensity reduces as the square of the increase in distance from source to target?

Seems to me that many of us, including the OP, could do with a quickie on those things :-)

TrentePieds

[StuM]

Originally Posted by topmast

You trying to say something?