Electronics > Beginners
Powering cheap 10w LED from eBay
Audioguru again:
--- Quote from: skillz21 on August 09, 2019, 01:09:00 pm ---
I feel like I'm missing something here, so please correct me if I'm wrong. The listing said 9-12v, so I'm guessing that it's fine to drive them at a bit higher than their forward voltage... right? As for the current, going off their maximum recommended voltage of 12v, I should be trying to push about 830mA to achieve the advertised 10w... right?
--- End quote ---
Why do you think the ad for the extremely cheap LEDs is truthful? Maybe the LEDs are defective and will never draw as much current as you calculated without burning out.
soldar:
A lot of these people selling on eBay from China have no idea about what they are selling. To them 500,000 mAh and 100 W are just labels they stick on products. I hope no one thinks Chinese engineers are selling stuff on eBay.
Whenever I have bought stuff like that, that did not measure up to the specs published in the listing, I have messaged the seller with a detailed explanation, photos of the testing setup and of the readings, and they have always, invariably reimbursed my payment. If it is worth your time you can do it.
As I say, most of the time the sellers have no idea what they are selling and I have ended teaching them some electronics. Some sellers just copy the text of a similar listing and you end up with an AC item when it was listed as DC, or a battery with tabs when it was listed as no tabs, etc.
sleemanj:
It is not a magic led, it has no active current control, no built in resistance, it is just 9 led die arranged in a 3 parallel strings of 3 in series, you need to drive it properly like any other led, you hang it on an unrestricted power supply above the fwd voltage (~10v) then it will not survive long and will fail in some way, yours appears to be failing to a high resistance state.
Get a fresh one you have not abused, dial your current limit to 900mA or use a 2.7R-ish 5W resistor, and try again.
skillz21:
--- Quote from: Audioguru again on August 09, 2019, 02:21:12 pm ---
--- Quote from: skillz21 on August 09, 2019, 01:09:00 pm ---
I feel like I'm missing something here, so please correct me if I'm wrong. The listing said 9-12v, so I'm guessing that it's fine to drive them at a bit higher than their forward voltage... right? As for the current, going off their maximum recommended voltage of 12v, I should be trying to push about 830mA to achieve the advertised 10w... right?
--- End quote ---
Why do you think the ad for the extremely cheap LEDs is truthful? Maybe the LEDs are defective and will never draw as much current as you calculated without burning out.
--- End quote ---
I don't think that it's truthful. @sleemanj is telling me that the listing was correct and that I'm not powering it correctly.
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