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Piranha LEDs

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juststarting

New Member
On a project I have been working on I have been using LED lights.
The problem I have come across is trying to get the light even over the whole board, (too narrow a light spread)
I have recently come across piranha5 domed LEDs in Red and Blue which are said to have a much larger spread of light, (but I have no specifications.)
I don't want to destroy these,
So my questions are,
1. is the operating voltage likely to be the same as an ordinary LED.?
2. will the same principle apply to calculating the resistance required.?

Thanks in anticipation,

Baz
 

atferrari

Well-Known Member
Simply by googling I got this (Sparkfun site)
 

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audioguru

Well-Known Member
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I do not believe it. The Chinese forgot to show which pin is which on their Piranha datasheet. You will need to measure it to find the common cathode. Why does it have three LEDs?
I guess they use 3 LEDs to make it bright and cheat by focussing the light into a narrow angle, but the text says 90 degrees and the graph shows only 10 degrees.

You should use an American LED, the Luxeon Superflux (by Philips) that has a single 70mA LED in the same 4-pins case as the Chinese Piranha. You can believe what their datasheet says. I have some and they are very bright with a wide viewing angle.

The graphs in a datasheet show only a "typical" device (that you cannot buy, you get whatever is available), the printed spec's show the range of minimum and maximum values for forward voltage. Calculate the value of the current-limiting resistor with the lowest forward voltage then none will burn out.
 

Tony Stewart

Well-Known Member
Most Helpful Member
Exactly what beam pattern and intensity do you want?
LED's come in a wide range of lens angles. When you double the angle, the intensity drops in half for the same family approx. Then inverse squared distance attenuation law applies.

Is this just for a prototype? (1) What specs you need?
 

Tony Stewart

Well-Known Member
Most Helpful Member
The cathode is easily identified by the cup holder and the dwg is marked pin 3 & 4

However the dwg shows 20 deg beam which is more likely wrong as it shows 60deg. in table.

Numerous spelling errors, sloppy work. Unreliable specs.

RGB =3
 
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audioguru

Well-Known Member
Most Helpful Member
The confusing Chinese datasheet does not say RGB, instead it shows 3 red LEDs and the spec's for red LEDs. Later pages show the spec's for a red LED, a green LED and a blue LED. The mechanical drawing of the LED shows two beams joining pin 1 to pin 2 and joining pin 3 to pin 4. Then there are only 2 connections for its 3 LEDs which is impossible. My Luxeon Superflux LEDs that have only a single LED also join those same pins.
 

Tony Stewart

Well-Known Member
Most Helpful Member
I believe their part number defines the colour of which they use 3 chips in parallel of the same colour and Red is just an example of choices between RGBWY

I would avoid this supplier like the plague.
 

juststarting

New Member
Thank you all for the info,
The piranha's I acquired were found in the bottom of a friends "bit's box"
I searched the oracle, (g----e) but could not find any info.
following the file sent, I noted the forward volts was very similar to the led's I have been using, so wired them the same.
Yes I did have a problem with the specs, (no indication of anode and cathode.)
call me lucky but it worked. (nice bright, clear, even light)
I need a light in the wavelength of 470 to 630 nm, as bright as possible, yes this is a prototype, need summat more reliable.
not sure if this is allowed, (advertising) but as I am soon to be in the market for some more piranha LEDs,
can anyone suggest a make I can trust, (I believe red and blue will give me wavelength I require)

thanks again for all your help

Baz

What could possibly go wrong ?
 
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audioguru

Well-Known Member
Most Helpful Member
I mentioned Luxeon Superflux American LEDs by Philips. They are reliable, very bright and have a wide beam angle. They have the same case as the Piranhas. But they have only one LED, not three.
 

EvilGenius

Member
I used these types of LED many times in the past. I bought them from China in larger packages (100 pcs - 1000 pcs). I like buying them from the "Same Bin".
Some manufacturers call it Piranha and others call it Superflux. They come in single color one chip, single color 3 chip, dual color and RGB.
Be aware some are common anode and some are common cathode. The ones with lens (not flat top) have view angles of 45 to 140 degrees (2xphi). If they say lower or higher angles, I would not trust the datasheet. The low mcd ones are really low and a waste of money, and some of the higher mcd above 3000 may not be accurate. Typically you can expect 90-100 degree view with typical Vf of (@20 ma, Vr=1.9 Vg=2.9 Vb=3.0). By the way they are very sensitive to overheating by solder iron and static charge! They have a small notch on one of the corners (hard to notice from distance). The pin immediately to the left of this notch (not under it) is the common pin (A or C). For RGB version notch depicts Red and going counter clockwise looking at it from the top, you have Green, Blue, and then common (A or C). Buying in large quantity comes out much cheaper even with a few duds here and there. Hope this helps.
 

EvilGenius

Member
My white 5mm 30 deg LEDs are 16-20 Cds, also avail in 30Cd. brightest in the industry
I guess anyone in US, Europe or China can produce any kinds of LED with different specs and call it what they want since there is no policing or reinforcement of quality standards or copyrights. So I retracted my previous comment earlier. Datasheets from China are not very reliable (or consistent) and best way to determine the quality of an LED product is to purchase a batch and test them yourself and hope that next batch gives you somewhat similar results. Cheers.
 
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