talk to me about GOOD LEDS

[mth5044]

speaking of "good" LEDs:

Wouldn't it be cool if you could dial in the wavelength with a rheostat? 400-700nM, hardwire it in once you get the shade you're after. In my imagination it's a clear, 5mm, 3-lead package, one resistor for brightness, one for wavelength. I guess until we have those quantum resistors everyone's been talking about it might be left to my imagination. The colors of LEDs are produced by the materials making the P-N juntion, yeah? Guess it would be hard to alter that with a 10K pot.

They've got them tri-color LED's that cross the spectrum. I think this would work, but a little beyond your ideal setup, with 4 pins, and you'd need 3 rheostats (and 3 limiting resistors so you don't blow the LED) to blend the colors. You could then use some precision resistors when you dial in each legs resistance to hard wire it.

Alternatively you could use some micro controller magic to get down to one or two pots, but then you'd have to plant that micro controller in every situation.

[PRR]

You can get "RGB" LEDs with 3 LEDs and 4 leads. Feed different current to each LED, you can change the "color" (not the wavelength).

High-end approach: http://www.linear.com/product/LTC3212

There may be LEDs with PICs inside. I know there are ones that change color constantly- whether they made them to be controlled in some pot-simple way I do not know. I know the blinkers, and maybe the cyclers, can cause switching noise inside high-gain audio.

[amptramp]

Back in 1981, I was one of the people who received one of a shipment of 20 silicon carbide blue LED's.  The wavelength was 480 nanometres which was a real blue jeans blue.  Light emission was first seen on silicon carbide electrodes in electric arc furnaces where the electrodes would flash yellow and blue.  These were made on a 3/4 inch wafer which is why they never went into series production.  We were buying green LED's as bare dice and one of the advantages of silicon carbide was you were never going to get the pick-and-place machine to crush the dice if they were silicon carbide.

I kept the LED in my wallet as a good luck charm but thought better of it in case my wallet ever got examined at a border crossing, so I took it out and put it somewhere.  And I have never seen it since.

[garcho]

I hear y'all on combining LEDs, but it doesn't work like pigment paint. to look right, IMO, they need to be "made" the color they are. And the auto-fade color changeroo jobbers make a ton of noise!

[EBK]

I hear y'all on combining LEDs, but it doesn't work like pigment paint. to look right, IMO, they need to be "made" the color they are. And the auto-fade color changeroo jobbers make a ton of noise!

I know that you weren't addressing this directly, but it reminded me that a large part of the potential confusion between light colors and paint colors is the disservice (my opinion) of continuing to  teach elementary schoolchildren that red, yellow, and blue are primary colors.  We should be teaching them instead that magenta, yellow, and cyan are subtractive primary colors and red, green, and blue are additive primary colors.  Sorry for the rant.

[stallik]

Rant away to your hearts content on this one Eric! This one does my head in. I even went as far as proving  the theory to my daughters teachers but was met with a 'not in the syllabus' brick wall. I also learned not to embarrass her at school.

[mth5044]

I hear y'all on combining LEDs, but it doesn't work like pigment paint. to look right, IMO, they need to be "made" the color they are. And the auto-fade color changeroo jobbers make a ton of noise!

I know that you weren't addressing this directly, but it reminded me that a large part of the potential confusion between light colors and paint colors is the disservice (my opinion) of continuing to  teach elementary schoolchildren that red, yellow, and blue are primary colors.  We should be teaching them instead that magenta, yellow, and cyan are subtractive primary colors and red, green, and blue are additive primary colors.  Sorry for the rant.

I remember in a class in college when a professor was showing us the color spectrum with red, blue and green as the primary colors. One of the most confusing lectures of my life. I thought there was some sort of conspiracy. Had never heard that mixing colors of light vs. mixing pigments were different in my life until I was 22.

[ulysses]

not sure why there are replies on here that are intended to be put downs??

i guess thats the way of the internet these days. jumping on there to say "you're wrong"

given the arguments presented here you could presume no leds are designed better, and made to a better quality than another.

ive had experience with shitty leds. i want to buy ones that have had better design and manufacture. it's simple.

if you don't have anything to add beyond the request, why bother? to put negativity into the world? seems pointless to me.

[Kipper4]

I see this as an open discussion with some good points.
Not really feeling negativity.

I just buy the shitty led 'cause what I need them for ain't critical.
I've never thought about buying better designed and manufactured leds.
Is there even a point? from a manufacturers point of view It's probably not worth upping the qaulity of the product since most will be behind some screening all it's working life.
Furthermore would a big enough portion of the market be prepared to pay for them. To warrant the initial outlay.

Keep em cheap.
But I'm just a cheapskate hobbyist.

[Rob Strand]

not sure why there are replies on here that are intended to be put downs??

I agree with what you are saying but I didn't get that impression.  Maybe you should have elaborated on your bad experiences - yeah, I know, easy to say after the fact.

Personally I haven't had any issues with "bad" LEDs for about 20 years.  Before that you definitely got dim ones,   inconsistent colors.   I always found the ones with milky white plastic particularly weak and feeble looking.

I've had issues in professional products where you want the product to look the same when you put different production builds side by side.  For example an LED goes obsolete and the replacements were brighter and had a slightly different color.  It's a more an issue of wasting time tweaking currents and creating paper work for the engineering changes.    Another aspect is the color of the plastic.

(Not relevant for effects but from a scientific perspective the color and output of LEDs can vary with temperature - that might screw-up your experiment.)

[ulysses]

I agree with what you are saying but I didn't get that impression.

yeah fair enough

[BetterOffShred]

I also purchase LED's by the sackful and other than frying a couple here and there I've never had a bad one.  I think all these comments are great and I've enjoyed reading everyone's experiences. 

Yeah I don't think anyone meant to sound like a dick

[duck_arse]

why not use a popular search engine to find some of the world's LED manufacturers, then look their webpage for "samples". find if they have the type/colour/package you want, then request some samples. IF they reply and send parts, then you can evaluate/compare/contrast same. if they don't care to reply, cross them off your list.

[garcho]

not sure why there are replies on here that are intended to be put downs??

if regular ol' non-GOOD LEDS are good enough for Neve, Moog, Mesa/Boogie, every boutique pedal maker, etc. they're good enough for you. You can take that as an insult or a put down or whatever or you can take it as the end of the road for your LED search and move on to something else having benefited from collective wisdom.

[anotherjim]

No one has said it, but perceived unreliability of a component type can be due to unintended abuse in assembly. For LED's, excessive soldering temperature is damaging. Normal soldering done too close to the body is causing damage. Bending the wires close to the body is causing damage.

[davent]

No one has said it, but perceived unreliability of a component type can be due to unintended abuse in assembly. For LED's, excessive soldering temperature is damaging. Normal soldering done too close to the body is causing damage. Bending the wires close to the body is causing damage.

... missed current limiting resistor?

[ulysses]

i just wanted to say thank you to those that responded to my post positively. i really appreciate you taking the time to put positivity into the world.

i ordered some CREE and some Kingbright leds. the build quality seems excellent -- i feel a whole lot better about knowing my leds have been designed and manufactured well.

thanks again, ulysses.