Recent content by txg

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    Homemade Ceiling Light Fixture with Bridgelux (Pics Included)

    did you take these measurements with a cheap standard multimeter? that would explain the bad efficiency with dimming, because the measurement is inaccurate. to measure the ac current, you'll need a true rms multimeter or a scope.
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    Where to buy XP-G Warm White R2 & Neutral White R3?

    the greenish color stays there with lower drive currents, but i believe that it is a tad less annoying. the bin of these xp-g is 7D.
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    Where to buy XP-G Warm White R2 & Neutral White R3?

    did anyone receive a warmwhite xp-g and has some opinions on it yet? my warm white q5s arrived today, and i'm testing them at the moment, four of them in series on a cpu cooler, driven by a constant current source up to 1.6 Amps. to be honest, i'm actually not as pleased as expected...
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    Where to buy XP-G Warm White R2 & Neutral White R3?

    how do you know there is a warm white r2 bin? the actual datasheet only lists q5 as the highest bin. edit: sorry, my fault. it seems like they actually exist if you're looking in the binning and labeling pdf, but they are only available in 3500k, which is perhaps a bit too cold if mixed with...
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    USB Battery capacity testers?

    if you are willing to take some time and are able to solder there is another possibility: http://stefanv.com/electronics/battman2.html if you've got some spare parts, e.g. the housing and a cooler, lying around, you can build the battman II for about 20$.
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    I want a 32lumen per watt halogen bulb

    I'm sorry to say that, but your tests actually confirmed nothing, because you just simply can't compare different bulbs running at a different wattage. grab a multimeter and a laboratory powersupply, and test this magic philips bulb at the same wattage as a standard halogen bulb. this way, a...
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    I want a 32lumen per watt halogen bulb

    even if there is no adjustable power supply available, are you able to measure the current flow through the 12v halogen lamp? that would help getting a better estimation of its efficiency.
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    universal charging cradle prototype with individual ballance taps

    here is my solution for charging my 14500s in parallel: It's the christmas gift of my brother, he built it on his cnc mill. works great, but you have to be careful not to overtighten the screws.
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    BessieBenny's Budget LED (DX/KD etc) Flashlights Review Roundup (Part XII)

    i just received 2 lights from dx and i want to share my opinion on them: trustfire xp-ef23 (sku.24291) this is one hell of a light, it is as bright as my k-106 (both running on li-ions, [email protected], [email protected]). VERY solid finish, looks and feels like a very expensive light. user...
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    The new XP-G: another big announcement from CREE

    although there isn't anything said about the 230v being alternating current, you're totally right about this absolutely stupid idea. interestingly, on the german page about the led, resistor suggestions stop at 24v.
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    Power Supply suggestions?

    Perhaps you've got some old printer power supplies around? these are often 30V & 1Amp, they are efficient and without fan. you can re-arrange your 48v/350mA setup to 24v/700mA, then it will work with a matching driver.
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    The new XP-G: another big announcement from CREE

    If you're from europe, there's a german seller here: http://www.leds.de/p804/High-Power_LEDs/Cree_LEDs/Cree_XP-G_R4_weiss_325_Lumen.html but it's only R4 at the moment...
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    Any charger for Li-ion that stops below 4.20V?

    as for laptops, don't wait any longer ;) with ibm (now lenovo) thinkpads this is possible since ca. 2004. in their battery manager, you can enter the level in per cent where charging should begin (e.g. 85%) and where it should end (e.g 90%).
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    The new XP-G: another big announcement from CREE

    thats just great. i've done some math with the assumption that efficiency losses at higher currents are the same with xp-g r4 and s2. what i got is an output of 387 lumens for an xp-g s2 @ 1000mA. this is SO great, keeping in mind that the best led before was an xr-e r2 with 242 lumens...
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    The new XP-G: another big announcement from CREE

    but there are voltages in the data sheet... Forward voltage (@ 350 mA) V 3.0 Forward voltage (@ 700 mA) V 3.2 Forward voltage (@ 1000 mA) V 3.3 the very low forward voltage (xr-e @ 1000mA is 3.7V according to their datasheet, 3.5V measured by jtr1962) could actually cause a lot of problems...
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