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Mains voltage LEDs?

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MarkS:
My mind was wandering last night while I was trying to go to sleep, as it typically does, and I came upon the weird thought as to why there are no mains voltage rated LEDs. Most LED home lightbulbs use inefficient capacitor droppers and this is the primary failure point. My initial thought was that it's an issue of putting that much voltage and current across a doped piece of silicon, but then remembered rectifier diodes, SCRs, thyristors and the like. Clearly, it's "possible". Is there a technical reason as to why this doesn't exist, or does it exist and I'm just unaware?


[edit] A quick Digi-key search and I found some! But, they're obsolete.  :-//

thm_w:
There are various 3V, 6V, 12V etc. LEDs with matching number of dies in them. You take 10 or 20 of those and put them in series.
This allows you to spread out the heat easier.

But yes, COB LEDs with 30+ die inside also exist. Its just that you'll get a lot of 60Hz flicker from them if run directly.

You can find a lot of good variations from big clive

tom66:
There are definitely mains voltage LEDs.  I'm sure Clive has done a teardown on one that used linear regulation of a ~250V strip from the 320V rectified capacitor supply.  And I don't mean that video above, but a COB LED that is all the required LED die in series.

TimFox:

--- Quote from: MarkS on February 17, 2023, 08:41:57 pm ---My mind was wandering last night while I was trying to go to sleep, as it typically does, and I came upon the weird thought as to why there are no mains voltage rated LEDs. Most LED home lightbulbs use inefficient capacitor droppers and this is the primary failure point. My initial thought was that it's an issue of putting that much voltage and current across a doped piece of silicon, but then remembered rectifier diodes, SCRs, thyristors and the like. Clearly, it's "possible". Is there a technical reason as to why this doesn't exist, or does it exist and I'm just unaware?


[edit] A quick Digi-key search and I found some! But, they're obsolete.  :-//

--- End quote ---

Rectifier diodes, thyristors, transistors, etc. can tolerate relatively high voltages across reverse-biased PN junctions.
However, forward-biased junctions operate at relatively low voltages: roughly 0.2 or 0.3 V for Ge or Schottky Si diodes, 0.6 to 1 V for PN Si diodes, > 2 V for LEDs (depending on color).
To emit light, an LED must be forward-biased.

MarkS:

--- Quote from: TimFox on February 17, 2023, 10:49:11 pm ---Rectifier diodes, thyristors, transistors, etc. can tolerate relatively high voltages across reverse-biased PN junctions.
However, forward-biased junctions operate at relatively low voltages: roughly 0.2 or 0.3 V for Ge or Schottky Si diodes, 0.6 to 1 V for PN Si diodes, > 2 V for LEDs (depending on color).
To emit light, an LED must be forward-biased.

--- End quote ---

Thank you! I knew it was something like that, but couldn't remember exactly what.

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