What did you mod today?

EasyB · December 9, 2016, 4:04pm

Mitko and DB custom reported the W2 would do ~6.6A on direct drive, so a bit lower Vf. But I haven’t heard they are dying from direct drive.

Did you have a U3 XML2 or XPL?

pilotdog68 · December 9, 2016, 4:06pm

They were XM-L2’s that died, but when I reported it I realized that it wasn’t just me, U3’s were dying for everyone. So I was wondering if there is a similar “cursed” bin of XP-L’s

giorgoskok · December 9, 2016, 4:07pm

THANK YOU !

Burned 3 xm-l2 U3’s in one C8 .

Now it’s running U4 without issues

EasyB · December 9, 2016, 4:08pm

I see. I have not heard of any cursed XPLs. The V6 will do 6A on direct drive, typically. The W2 a bit more.

Enderman · December 9, 2016, 7:36pm

Well this XP-L had a section of the die die (lol) under 6A, imagine if you drive it at 4.2v from a lipo…

vwpieces · December 9, 2016, 7:38pm

My first 7135 stacking. Thorfire BD04 now with XM-L2 T6 3B

Enderman · December 9, 2016, 7:40pm

EasyB:

This is interesting. The details of this are not often discussed. I think for largish diameter lights this definitely makes a significant difference in how we would calculate the throw (cd).

I think you explained it fine; this is just some further explanation of my understanding of the subject. The inverse square law, which we use to calculate the cd, is valid for a point source of light and the distance in the formula should be from the point of light to where you measure. With flashlight beams, the light appears to come from a point behind the flashlight, not the face of the flashlight, and so this effective distance should be used in the formula, (cd)=(lux)(d^2), instead of just the distance to the flashlight.

Something bothers me about that calculator you linked, though. It implies that (with all other things the same) the size of the emitter affects the divergence distance behind the aperture. This somehow doesn’t seem right to me. I did some quick tests with my UF 1504 lens light. To get a more accurate measure of this effective divergence distance, I measured the beam size at different distances (2.5m, 4.2m, 10.2m from the lens), then simply graphed the points and drew a line through them. The point at which the line crosses zero is the effective point from which the light is emanating. I did this with two different sized emitters, the dedomed old XPG2 and the XPL HI, and got equal divergence distances behind the lens, 2.5m. This means, effectively, that the beam size is not the size of the lens at the lens. Anyway, I don’t understand all the implications, just wanted to put it out there.

It’s not the size of the emitter that matters, it is the size of the aperture of the flashlight.
I actually didn’t know how the website algorithm worked, so I took out my trusty calculator and did some simple trig, and I did get the same value as the website.
Basically imagine a triangle, starts at one point, and at 10m has a spot that is 10cm.
That is far more divergence than a rhombus that starts at 5cm and at 10m has a 10cm spot. (which is a section of a much looonger triangle)
As you can see, the second case has a lot less divergence than the first.
The square law of light “calculate back to 1m” method works for case 1 but not case 2.
I will draw a pic later today to illustrate this for other people

CRX · December 9, 2016, 7:48pm

DQG Hobi MT-G2

EasyB · December 9, 2016, 8:12pm

Well according to that calculator the beam size and the aperture are what matters. The beam size is determined in part by the emitter size (they are roughly proportional).

I agree with what you say, but I think the calculator is not completely right, for the reason I explained above. Imagine you have your lens, but you can switch between two different sized emitters. The two emitters will make different sized beams (measured at whatever distance), and so that calculator would predict different “divergence distance behind aperture” for each emitter. I am arguing that this is not accurate; they should have the same “divergence distance behind aperture”.

My measurements showed that this distance is the same for different sized emitters, and I think this makes sense. Imagine having one emitter, then putting another emitter right next to it to effectively double its size (in one dimension). Nothing has physically changed about that first emitter, but the calculator predicts a significantly different “divergence distance behind aperture” value. I think that is not physically accurate.

The calculator is essentially using two data points to draw a line to calculate this distance, the beam size at the aperture (which it assumes is the same size as the aperture) and the beam size that you actually measure at some distance away. The way I calculated the distance is by actually measuring the beam size at 3 different distances and drawing the line. I get a different result than the calculator; the effective beam size at the aperture is not actually the width of the aperture. More measurements are needed to fully understand this.

Rufusbduck · December 9, 2016, 8:12pm

Nice clean solder work. :+1:

vwpieces · December 9, 2016, 8:19pm

Thanks RBD,
2AM project… hope it works.
With that said I did something stupid. Hooked to Bench PSU with reversed polarity. It’s from a Thorfire BD 04 and the driver is build different (wrong, backward).
Original emitter is dead so, will see shortly if driver survived.

emarkd · December 9, 2016, 8:34pm

Very pretty solder work, and not an easy thing to do. At least, its not easy for me to do

If you want to save a bit of time and effort, next time skip the center pins. Its continuous with the ground tab in the back so as long as one of those is connected it’ll all work fine.

Rufusbduck · December 9, 2016, 8:49pm

And in most cases the base level center pads aren’t connected to the ground ring anyway so the only possible benefit is a smidge more heat sinking from the added solder mass.

Enderman · December 10, 2016, 12:39am

EasyB:

Well according to that calculator the beam size and the aperture are what matters. The beam size is determined in part by the emitter size (they are roughly proportional).

I agree with what you say, but I think the calculator is not completely right, for the reason I explained above. Imagine you have your lens, but you can switch between two different sized emitters. The two emitters will make different sized beams (measured at whatever distance), and so that calculator would predict different “divergence distance behind aperture” for each emitter. I am arguing that this is not accurate; they should have the same “divergence distance behind aperture”.

My measurements showed that this distance is the same for different sized emitters, and I think this makes sense. Imagine having one emitter, then putting another emitter right next to it to effectively double its size (in one dimension). Nothing has physically changed about that first emitter, but the calculator predicts a significantly different “divergence distance behind aperture” value. I think that is not physically accurate.

The calculator is essentially using two data points to draw a line to calculate this distance, the beam size at the aperture (which it assumes is the same size as the aperture) and the beam size that you actually measure at some distance away. The way I calculated the distance is by actually measuring the beam size at 3 different distances and drawing the line. I get a different result than the calculator; the effective beam size at the aperture is not actually the width of the aperture. More measurements are needed to fully understand this.

The emitter size is what affects the divergence.
If it was a point source, the rays would be collimated and the spot size would be equal to the projected size at any distance, which results in an infinite candlepower.
If you use the calculator and put the same aperture and spot size you get a divide by 0 error.

Since an LED is not a point source, the spot at 10m is larger than the aperture, which means there is divergence, and that is what needs to be taken into account.
And “aperture” refers to the initial diameter of the beam when leaving the flashlight. So the beam size is literally another way of saying aperture.
Obviously if you have a huge lens and only use 2cm diameter of it you would put 2cm as the aperture, not 200cm or whatever.

MRsDNF · December 10, 2016, 12:54am

+1 on on what RBD said. Looks orsm. Well done.

vwpieces · December 10, 2016, 1:01am

Thanks,
Have it fully assembled now, IT WORKS!!
Happy because it survived a 2AM Brain Fart.

Rufusbduck · December 10, 2016, 1:50am

That’s what D1 is for.

staticx57 · December 10, 2016, 1:53am

Coming along quite well. This is a really nice Reylight host. MTN-17DDm with 3000k 80CRI XPL HI. Still need to polish it and glue in the trits.

EasyB · December 10, 2016, 2:25am

Enderman:

EasyB:

Well according to that calculator the beam size and the aperture are what matters. The beam size is determined in part by the emitter size (they are roughly proportional).

I agree with what you say, but I think the calculator is not completely right, for the reason I explained above. Imagine you have your lens, but you can switch between two different sized emitters. The two emitters will make different sized beams (measured at whatever distance), and so that calculator would predict different “divergence distance behind aperture” for each emitter. I am arguing that this is not accurate; they should have the same “divergence distance behind aperture”.

My measurements showed that this distance is the same for different sized emitters, and I think this makes sense. Imagine having one emitter, then putting another emitter right next to it to effectively double its size (in one dimension). Nothing has physically changed about that first emitter, but the calculator predicts a significantly different “divergence distance behind aperture” value. I think that is not physically accurate.

The calculator is essentially using two data points to draw a line to calculate this distance, the beam size at the aperture (which it assumes is the same size as the aperture) and the beam size that you actually measure at some distance away. The way I calculated the distance is by actually measuring the beam size at 3 different distances and drawing the line. I get a different result than the calculator; the effective beam size at the aperture is not actually the width of the aperture. More measurements are needed to fully understand this.

The emitter size is what affects the divergence.
If it was a point source, the rays would be collimated and the spot size would be equal to the projected size at any distance, which results in an infinite candlepower.
If you use the calculator and put the same aperture and spot size you get a divide by 0 error.

Since an LED is not a point source, the spot at 10m is larger than the aperture, which means there is divergence, and that is what needs to be taken into account.
And “aperture” refers to the initial diameter of the beam when leaving the flashlight. So the beam size is literally another way of saying aperture.
Obviously if you have a huge lens and only use 2cm diameter of it you would put 2cm as the aperture, not 200cm or whatever.

Yes, everything you say is fine. I’m just saying that some of the details of that calculator differ from the measurements I just took.

Enderman · December 10, 2016, 3:01am

It really depends on how well your flashlight can collimate, this method is almost irrelevant for regular reflector LED flashlights.
I made a separate post to explain everything: The proper way of calculating lux / cd / candlepower