General > General Technical Chat
Software guys, please, no.
fourfathom:
Seems appropriate:
tooki:
--- Quote from: pcprogrammer on September 20, 2022, 04:27:29 pm ---
--- Quote from: tooki on September 20, 2022, 04:04:08 pm ---That's clearly a modern emerald green (~520nm) LED, and those have significantly higher forward voltages (3-3.5V) than traditional lime green LEDs. So when connected to a 3.3V power source, many of them are right in their happy place, even without a current limiting resistor.
If we were talking about old-fashioned 1.7-2.2V LEDs, then it'd clearly be problematic. But with modern 3V+ green/blue/white LEDs, it's actually not preposterous.
--- End quote ---
Well that shows that I have been out of the real hardware game to long. I knew blue LEDs had higher forward voltages, but not that there are new types of green that have higher forward voltages.
Thanks for the bringing my knowledge up to par a bit :-+
--- End quote ---
My pleasure!
The other thing about such LEDs is that they're insanely bright. The "standard" 20mA for indicator LEDs is blindingly bright with those things. As a pure indicator for indoor use (i.e. similar brightness to a 1980s LED at 20mA), I often run them at 1mA or less! (For example, running one on 5V using a 10K resistor, providing roughly 200uA.)
deadlylover:
Come on guys it's a freaking YouTube tutorial video for beginners, not an ISO17025 procedure or whatever. :-DD
Sheesh I'm surprised the anti-static gang hasn't shown up yet.
pcprogrammer:
--- Quote from: tooki on September 20, 2022, 04:53:34 pm ---The other thing about such LEDs is that they're insanely bright. The "standard" 20mA for indicator LEDs is blindingly bright with those things. As a pure indicator for indoor use (i.e. similar brightness to a 1980s LED at 20mA), I often run them at 1mA or less! (For example, running one on 5V using a 10K resistor, providing roughly 200uA.)
--- End quote ---
Yeah, I have found that out with smd leds. These things do not need a lot of current to be bright.
fourfathom:
--- Quote from: pcprogrammer on September 20, 2022, 05:21:52 pm ---
--- Quote from: tooki on September 20, 2022, 04:53:34 pm ---The other thing about such LEDs is that they're insanely bright. The "standard" 20mA for indicator LEDs is blindingly bright with those things. As a pure indicator for indoor use (i.e. similar brightness to a 1980s LED at 20mA), I often run them at 1mA or less! (For example, running one on 5V using a 10K resistor, providing roughly 200uA.)
--- End quote ---
Yeah, I have found that out with smd leds. These things do not need a lot of current to be bright.
--- End quote ---
I run my on-board indicators (red, 0603 SMD, 1.8V) at 3.3V, 10K resistor (590 uA) and they're still too bright.
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