suggestion: M140 diodes with output specs

I wish someone would part out a projector and test/sell the diodes according to their output specs...

something like this (output @ 1.6a):
(1) - $75 > 1.9watt
(3) - $65 > 1.8watt
(5) - $55 > 1.7watt
(6) - $45 > 1.6watt
(5) - $35 > 1.5watt
(3) - $25 > 1.4watt
(1) - $15 > 1.3watt

Total:
(24) - $1080 - avg 1.6watt

I think the highest and lowest would have no problem selling with those prices... surely even add $5-10 to the prices since they'd be tested...

That's a neat idea, and I've thought about doing that with wavelength now that I have a spectrometer.

There's a problem though. No individual seller could ever sell the lower binned diodes for $15 or $25. Well they could, but what you would see is that almost immediately someone would buy them (the Chinese, or just regular folk looking to make a few bucks), and they'd show up on eBay.

If someone was willing to sell "1.3W @ 1.6A" diodes for $15, someone smart would buy them all, accurately and honestly list them on eBay as 1.3W 445nm diodes, and sell them for $40 ($10 less than all the other sellers there), and they'd immediately scoop up almost ever eBay buyer, while still making a $25 markup per diode.

Basically what I'm saying is that you could never really drop the low end price below market 445 rates, without simply causing someone else to start buying them, marking them up, and selling them. The other half, marking up the high end, is certainly doable.

So, you're saying that all the diodes would sell easily? But... it's a bad idea, because someone else might mark the low-end ones up? Although, I see your point, it seems like the benefit would be worth it... People would love to buy the diodes with specs.

That's a lot of effort for little value to the seller. Most people would would either choose the top or bottom diode tier, leaving the average diodes alone. Plus how do you actually certify the diode power? Is it the max diode power that is being cited? The below-knee power? The long-life power? Can you even dispute such power levels?

I also think that while 1.3W to 1.9W is a noticeable difference, those other gradations are relatively meaningless for their price. Certainly 100mW power differences are unnoticeable, and I know that I would end up just buying diode from the cheaper tiers because I could put that money into a better lens or something longer lasting. In the end the going rate of $45 for an M140 diode is quite reasonable.

Bionic-Badger said:

That's a lot of effort for little value to the seller. Most people would would either choose the top or bottom diode tier, leaving the average diodes alone. Plus how do you actually certify the diode power? Is it the max diode power that is being cited? The below-knee power? The long-life power? Can you even dispute such power levels?

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The power level would be certified at 1.6amps (or 1.5amps or whatever), it would show the efficiency at a certain current, not a max.

I also think that while 1.3W to 1.9W is a noticeable difference, those other gradations are relatively meaningless for their price. Certainly 100mW power differences are unnoticeable, and I know that I would end up just buying diode from the cheaper tiers because I could put that money into a better lens or something longer lasting. In the end the going rate of $45 for an M140 diode is quite reasonable.

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So, you would like the $15 diodes... the high-end ones would sell fine... and the middle ones would sell for the normal price. At current projector prices, this still gives the seller ~$200 for the labor.

ekeup said:

So, you're saying that all the diodes would sell easily? But... it's a bad idea, because someone else might mark the low-end ones up? Although, I see your point, it seems like the benefit would be worth it... People would love to buy the diodes with specs.

Click to expand...

No. I'm saying that practically speaking, that first seller simply wouldn't list the low end diodes at $15. There'd be no reason for them to. Demand would always keep the value of those diodes up above $15, and somewhere pretty close to what we pay for normal diodes now. There are lots of sellers selling 445s for $50 and still labeling them as 500 to 1,000 mW diode. You could truthfully label a diode at 1.3W, and still get every penny of that $50 price tag (especially selling to the public, like on eBay, etc). So simply put, while I can see a seller marking up the tested high end diodes, they would never substantially discount the low end. (Unless you're talking like 300mW zombies). As much as that model may make sense in your head (or in a closed system), it doesn't work in reality, where each seller is just one of many harvesting the same diodes.

Bionic-Badger said:

I also think that while 1.3W to 1.9W is a noticeable difference, those other gradations are relatively meaningless for their price. Certainly 100mW power differences are unnoticeable, and I know that I would end up just buying diode from the cheaper tiers because I could put that money into a better lens or something longer lasting. In the end the going rate of $45 for an M140 diode is quite reasonable.

Click to expand...

Agreed. It's one thing for people to say that they can spot the different between 200mW and 250mW of DPSS like 532nm. It's an entirely different (and much more absurd) proposition for people to suggest that they can recognize 25% power differences in "445nm diodes". Using my spectrometer for the last week or so has really revealed to me the patent absurdity of any claim that someone can "eyeball" the differences.

Why? Because these "445s" all differ so hugely in wavelength. Granted, I've only spectrometered a couple dozen 445s so far, and that's not nearly as many as some of the guys on PL have tested, but even accross the 30 or so I've measured for wavelength, I've see a range of 441 to 453nm. That has HUGE implications for how bright a beam appears.

Now, there's a lot of debate over how well the various "relative brightness" calculations work for vastly different wavelengths (like comparing red to green), but I think the figures are fairly trustworthy for relatively close wavelength comparisons. So, imagine you run a multi-mode blue at 1,250mW of output. Not too impressive right? Well, if that's 1,250mW of 453nm, it would appear as bright as OVER 2W of 441!

Think about that for a second. Two diodes that you thought to be essentially identical, and yet one of them (the 453) running at 1,250mW would appear brighter than the other at 1,250, or 1,500, or 1,750 - in fact, they wouldn't appear to be on par until you got the 441 to ~2,018mW.
Beam: (453nm 1250mw) vs. (441nm 2018.21mw)

The assortment of diodes I have probably reflects the variety in most people's collections. Whether you've got two multi-mode-blues or twenty, chances are good that you've got different wavelengths, and perhaps wavelengths different by a fair amount. While you may not perceive a difference in colour between say 445 and 450, there's going to be a substantial difference in brightness. Even that little 5nm jump accounts for an extra ~20% in brightness.

So, basically what I'm saying is that anyone who claims a talent at spotting power differences between different "445s" is full of bologna, unless they know that the wavelengths are identical.

Perhaps the takeaway is really that we should be spectrometering all of our diodes. I'm certainly doing that with every diode I use from this point onwards.

It would probably work better if you were to sell them with >1500mW and <1500mW ratings at 1.3 amps.

The thing is there are no $15.00 diodes they do not exist !

An M-140 diode is at or above the middle as you describe it.

Even in a A-140 the diodes do not drop out at the bottom of your curve.

Flaminpyro said:

The thing is there are no $15.00 diodes they do not exist !

An M-140 diode is at or above the middle as you describe it.

Even in a A-140 the diodes do not drop out at the bottom of your curve.

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The curve was just an example. It should be adjusted based on the average diode. What do you think the ranges could be?

ekeup said:

The curve was just an example. It should be adjusted based on the average diode. What do you think the ranges could be?

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Instead of talking specifics (which change with the economics of projector supply, etc), just talk percentages.

With the "base price" being whatever a seller would normally sell their diodes for, I think you could discount the bottom 6 of 24 diodes by maybe 10%. Keep the middle 12 as normal, and increase the top 6 of 24 diodes by maybe 25%.

In practice -
I could see charging $50 instead of $40 for a known-efficient diode, and I could see charging $35 instead of $40 for a known inefficient diode.

not to thread jack but what are a140 diodes going for?

Hey rhd, I like your statement about using spectrometers on our diodes. It's spot on and may mean the difference between pushing a laser further and having diminishing returns because of wavelength shift. What hardware are you using for your spectrometry?

Off topic a bit but...
@ RHD....
did you finally calibrate your Spectrometer you bought
off eBay...:thinking:

Jerry

ekeup said:

So, you would like the $15 diodes... the high-end ones would sell fine... and the middle ones would sell for the normal price. At current projector prices, this still gives the seller ~$200 for the labor.

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We don't always take the whole picture into account. Take the best price I am seeing now out there in this Google search.Casio Signature XJ-M140 XGA (1024 x 768) DLP projector - 2500 ANSI lumens

Cost
Projector $869
Shipping $48 @ $2 each Postage+packing supplies
PP fees $43
Base costs $960

24X45= $1080
That leaves $120 over cost which the government will take at least 30% of as well.

That is a lot of work to put $84 in your pocket assuming you did not find a dud in the projector or other issues. I sell the bare diodes for $45 as a favor to the community also with the hope you will buy some of my other items. Trust me there is no windfall on bare diodes.:beer: