LED - Is 10mcd bright enough to see as indicator

[Jester]

I'm working on a project that requires a few 0603 indicator LED's (Indoor use only). The user would be close to the device when looking at the status LED's (30cm or less).

I'm also trying to minimize power dissipation.

This LED is rated at 7 mcd @ 2ma (~15 mLumens). : https://www.digikey.ca/product-detail/en/LS L29K-G1J2-1-Z/475-2506-1-ND/1802633


Will this be bright enough to observe clearly?

 

[Audioguru]

The LED is tiny. It will look like just a speck of light. It is not as bright as most modern LEDs but it has very wide viewing angle.

 

[Jester]

The LED is tiny. It will look like just a speck of light. It is not as bright as most modern LEDs but it has very wide viewing angle.

These will be used as an indicator on a small device. There will be four, all different colour, I don't think size is an issue as the user will be 30cm away or less, as long as they can see the LED when it's on.

 

[betwixt]

Buy one and see.

The answer to your question depends on other factors, for example, ambient light and whether some kind of lens or light pipe is to be used. For normal instrument panel indication where the LED is directly visible, 7mcd should be plenty.

Brian.

 

[Jester]

Thanks,

I will give it a try.

 

[D.A.(Tony)Stewart]

Luminous flux (Lux) is defined as 1 lumen/m² of a surface= 1 lx ,
; which is 1000 mlm/10,000mm² or 0.1 mlm/mm²

A typical office environment is 300 lx at desktop level.
. . . . while full sunlight is ~10k lx
. . . . and moonlight is ~0.1 lx

This LED is 1.70mm L x 0.80mm or 1.4mm² with the 2nd lowest group, G2 only producing 10 mlm.
Thus the Luminous flux would be 10mlm/1.4mm² or 7.1 [lx]

Now I don't know the reflection coefficient of the diffused surface , but let's pick 5%.

Then we get an unlit surface at 15 lx and when the LED is on 15 + 7 lx which doesn't sound like much but then the 15 lx is white so the resolution of Red should be noticeable but not brilliant.

 

[Jester]

Luminous flux (Lux) is defined as 1 lumen/m² of a surface= 1 lx ,
; which is 1000 mlm/10,000mm² or 0.1 mlm/mm²

A typical office environment is 300 lx at desktop level.
. . . . while full sunlight is ~10k lx
. . . . and moonlight is ~0.1 lx

This LED is 1.70mm L x 0.80mm or 1.4mm² with the 2nd lowest group, G2 only producing 10 mlm.
Thus the Luminous flux would be 10mlm/1.4mm² or 7.1 [lx]

Now I don't know the reflection coefficient of the diffused surface , but let's pick 5%.

Then we get an unlit surface at 15 lx and when the LED is on 15 + 7 lx which doesn't sound like much but then the 15 lx is white so the resolution of Red should be noticeable but not brilliant.

SunnySkyguy,

Thank you for an explanation that I can actually understand. I did to a google search and most explanations related to while light (headlight beams and such) with pages of formulas but nothing real world.

I will give these a try and either increase the current or pay for a better LED if they are too dim.

Regards,

 

[Audioguru]

My ordinary 5mm red LEDs are 200mcd at 20mA and have a 40 degrees total viewing angle. They are at least 10 years old.
Modern LEDs are brighter with a wider viewing angle.

 

[D.A.(Tony)Stewart]

Yes my Red 5mm LEDs are 10,000 mcd @ 20mA 30 deg and don't cost much more. So at 2mA they emit > 1000mcd.
If you want to emit light thru a small aperture hole. I would use<=20deg which only comes in 3 or 5mm and not SMD. If you need high volume or at least $500 worth I can find for you. Then you can drive at 2mA.