Hey TA, any update on where to purchase the BLF GT emitters? I believe their XHP35A H0 0000 0D0BD440E, I looked at a bunch of different sites, but the minimum order is 1000 and I don’t see myself needing more then 8-9. Do you think Lumintop would be willing to sell a few emitters on the side? I have no problem with paying a slight premium over the normal cost of some XHP35 Hi emitters if Lumintop would be willing to sell some.
I have wanted to do this same thing but have not found a source for them yet. I have been trying to talk Lumintop into selling the LED’s separately but that led us down the rabit hole of trying to find an even better LED.
We did find a 4500k that could be real nice but the samples they sent me were lost in transit and I have not heard anything since. Once things quite down with the GT group buy I will see about the LED’s again.
It seems like some of your highest outputs were between 2600 and 2700 lumen. This is a raw led, correct?
In a flashlight where you have losses in the reflector and lens, what do you think the “Out the Front” output would be?
DB Custom was saying the MF04 output might actually be 2700 lumen out the front. I’m pretty skeptical of that. You would need the raw led to put out at least 3000 lumen and I havent seen any measured that high.
Plus, I doubt the MF04 will be using a top bin led anyway.
That should be the positive pad. "Anode" essentially means "positive terminal"
If you're ever worried, and own a multimeter with a diode test function (on some multimeters, the diode-test and continuity function are the same), you can test that way. Although, come to think of it, I'm not sure if that would light a 12v emitter... I haven't tried that. Works great for testing all my 3v emitters though lol
Thank you, Lexel and Scallywag! They could just add a + in brackets to anode for the idiots around The multimeter test function is also my favourite for 3V leds so I was worrying about the 50% chance of killing my led.
TA, I need a clarification on the PWM efficiency test…
Many FET drivers use resistors to slow down the FET. When a light is PWMed this reduces current, improving efficiency.
In another thread I see you stating that efficiency improvements are caused by lower temperature.
Some of there surely are but I would be interested in knowing whether temperature is really the sole reason why you got not-so-bad efficiency here or is it a combination of temperature and lower current.
The resistor was very small on the FET (4.7ohm IIRC) , it would have negligible effect for the purposes of this test. It is there to prevent ringing and improve consistency at very low modes.
You are correct that adding a larger resistor is a way of transferring the heat from the LED to the FET. Although overall efficiency does not seem to be effected much in my testing except that the driver gets hotter now but the same voltage is burned off either way.
Yes, just the plain fact it is lower current also effects the final output along with the lower temperatures (they are related naturally).
I wish I had a good function generator so I could do a more scientific test but I stand by my results based on my anecdotal experience as well. Not to mention that most professional lighting uses PWM, that would not make sense if they would be loosing ~50–70 efficiency that some say. It makes perfect sense based on my results though where they would only be loosing 10–20 efficiency to maintain the same tint.
Overall while FET PWM is not perfect by any means, particularly on LED’s that tint shift I will have no issues at all using PWM to adjust the output vs a constant current. The minor difference in efficiency will not effect most people / use cases.
At a given current draw the battery will last exactly the same FET vs constant current. The only change will be the lumen output and in most cases the human eye will not even be able to see the difference without having them side by side.