Barkuti mentioned the LD25… And I can see they are from Simon?
IF so just contact that guy and he will do 10 plus order for free…
I ordered more than 200 drivers from Simon (I had special wishes without any amc 7135 current regulator on nanjg AK-47 C1 for making Djozz fet driver) for ultra budget price.
About that LD 25…
So basically:
- Aligator clamps for positive DMM wire clamped to spring
- Negative should be classic DMM wire probe touching driver outer ring?
With small wire we are raising/reducing current
But all that can’t be done with classic DMM? Right? We need constant current power supply for that?
(I think) Simon filmed the LD-25 current output adjustment video with a precision power supply with voltmeter and amperimeter because of simplicity: he uses the supply in constant voltage mode, making sure there's enough input voltage headroom to overcome the drop in the supply to driver wire and contact resistances, and reads the current pulled in the supply's amperimeter. If, for example, you determine input wires plus alligator clips and contacts have around 0.2Ω of resistance and you aim for 5A at the driver, make sure you add ΔV = I × Rpath = 5A × 0.2Ω = 1V to the bare minimum voltage the LD-25 needs at its input to deliver the current at the emitter. Failure to do this will result in the current capping at some point, if this happens just raise the input voltage accordingly and try again.
If no precision power supply with amperimeter display available a multimeter can be used amidst in amperimeter mode, just make sure you raise input voltage enough. ;-)
Barkuti, that video is of the previous model LD25.
But i think Kaidomain has the old version in stock.
I don’t know if the same trick works on the newest version, but the PCB layout it very different.
Mmmkay, I have an LD-25 new version from FastTech laying around and a precision power supply with amperimeter. Will check it out soon, just a little bit of patience.
No one said you “need” a precision power supply. You need a way to know how much current is the driver pulling, this can also be achieved with a clamp meter somewhere.
Wellp, some sort of voltage source is still required, one at least capable of our desired emitter current output and input, with enough voltage headroom for wire and contact voltage drops. A standard 5V 5A power supply may do, or maybe some sort of battery holder gizmo with 2S cells in a low state of charge and some :-) long wires. Heatsinking the driver inside an S2+ pill is a good idea just in case we do not have full input voltage control. If we use a multimeter for current measurement place it somewhere in the circuit, maybe with alligator clamps between spring and voltage source. If clamp meter place it around some connecting wire.
Android's ElectroDroid application has a handy voltage drop calculator where you can set wire lenght, gauge, current, etc.
So if the the oem specs are to be believed for the Archer M2 (600m beam distance = 90kcd), you have AT LEAST doubled the candela.
The Archer M1 uses a de-domed SST-40 and oem specs are 800m / 160kcd so compared to that the results are a little less impressive.
Can I assume the Archer uses some sort of FET / direct current driver and you are still using it? What battery are you using? Can you take tail cap current measurements?
I did some measurements on 3 of the best 2mm^2 LEDs, the dedomed XPG2 (new style), close sliced SST20, and white flat 2mm^2. The white flat is from Mouser and the item has a range of possible bins so I don’t know the exact bin. I measured the output by measuring the lux directly above the LED (80cm away) and assuming the light emitting surface is a Lambertian surface, which is a good approximation. See here some more information about this method. I use a Tondaj LX-1010B lux meter. The lumen numbers are approximately close to others’ measurements, but assume the usual 10-20% possible error.
I then measured the beam intensity of each LED in an EE X6 head powered by a constant current power supply. dedomed XPG2: 95.2kcd at 4.5A, sliced SST20: 92kcd at 4A, white flat: 111kcd at 6A. I calculated the luminance by dividing by the reflector area of 620mm^2 and assuming 90% reflector and glass efficiency. Then I scaled the output graphs according to this information and the luminance vs current is displayed below.
The white flat and dedomed XPG2 curves have close to the same relationship in the output and luminance graphs, which is expected since their dies have very similar areas. But the sliced SST20 luminance curve is high compared to its position in the output graph. I think this is explained by a non-uniform luminance across the SST20 die. The SST20 has a close slice, but obviously some silicone remains on the die, as pictured here. Near the edges of the die light can reflect off the silicone/air interface and exit the die to the side. This light doesn’t contribute to the light coming directly from the die; it bounces to the side and a higher fraction of it gets absorbed or emits to the side where it isn’t useful. You can see by looking at the lit die that the edges are less bright than the center, pictured below.
The other LED dies are much more uniform in brightness over their surfaces. I think this is the reason for the SST20 having a lower output than the other LEDs. But the measured luminance is high, even higher than the other LEDs for most of the curve. This is because measuring the luminance by measuring the beam center intensity from a reflector only measures the LED die-center luminance.
Conclusion:
These 3 LEDs perform relatively close to one another at a given current, but in real world use there are big differences. The dedomed XPG2 still performs well, but the high forward voltage means the current can be low, especially in a mulit-emitter light. The SST20 improves upon the XPG2 in this aspect with its lower voltage, but dedoming difficulties hold it back. The domeless white flat with its very low voltage and higher max output is the clear winner in some applications (multi-emitter), but driving a single emitter optimally might be more difficult.
You’re welcome. No particular reason for 6A except that it’s a moderately high current I might expect in a quad light with these emitters. Based on my output measurements the throw at 8A should be about 10% higher than at 6A.