| Electronics > Beginners |
| Powering cheap 10w LED from eBay |
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| amyk:
--- Quote from: ledtester on August 06, 2019, 02:04:47 pm ---It also could be they are "10W equivalent" bulbs... https://www.thelightbulb.co.uk/resources/lumens_watts/ (Attachment Link) --- End quote --- According to that chart a 5W LED would be around 30W incandescent equivalent... |
| sleemanj:
Ok there is either, a> something wrong with your measurement/supply; or b> these are not bare leds post a photo of the led, or a link to the listing. You drive bare LEDs with a constant current (or at least with a suitable resistor to limit the current), typical 3x3 die arrangement 10W leds should be run at about 900mA, and the much less typical single series arrangement of die should be run at about 300mA. |
| John B:
If it is one of those 3x3 die 10W chips on ebay or ali express, as you've discovered they are generally rubbish. However if you find them cheap enough, they can have their purposes. I've made a few light bars with 20 or more of these chips in parallel, with each chip running under 100mA and no heatsink. Generally this is frowned upon due to the uneven current distribution from manufacturing variation, but I haven't found an issue when all the chips are running just on the start of the conduction curve. They're in use all day. |
| Brumby:
--- Quote from: skillz21 on August 06, 2019, 11:22:41 am ---I guess I got what I paid for. --- End quote --- That's a sound philosophy you need to keep in mind at all times. When you see "cheap" there will be a reason. Maybe it's an oversupply someone wants to clear out - or maybe they're substandard in some way. When you see "cheap" from China there will be a reason - and the clearance of an oversupply is NOT likely to be one of them. (It's not impossible - but it's not the value bet.) |
| sleemanj:
--- Quote from: John B on August 07, 2019, 03:09:50 am ---If it is one of those 3x3 die 10W chips on ebay or ali express, as you've discovered they are generally rubbish. --- End quote --- If die matching is anything to go by, and opinions differ, but there is very high variability in "quality", I test and "grade" my batches of 10W leds, one batch I can get they will all match perfectly at 10 or less microamps, other batches a few hundred microamps, and other batches you have to push 10s or even more milliamps to get all the die lit. Even in good batches I get I find one or two bad ones. Just the usual Chinese "QC". |
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