General > General Technical Chat
Explain to me the (de?)-evolution of LED lightbulb technology
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BrokenYugo:
That's incredibly roasted, I thought those driver chips all had thermal throttling. Were the bulbs in enclosed fixtures? If so were they rated for it? I know that's a gotcha that a lot of people overlook with retrofit LED bulbs, though at $4 I'd expect them to be good for it.
amyk:
8.5W for 800lm, that's less than 100lm/W... but from the look of those pictures it seems a lot of the power dissipation was in the driver circuit itself.

--- Quote from: BrokenYugo on March 25, 2021, 02:11:02 am ---That's incredibly roasted, I thought those driver chips all had thermal throttling.
--- End quote ---
They do, they just throttle at a very high temperature.
james_s:
Hm those are newer than the Philips bulbs I have. Mine are mostly the older remote phosphor types, I have some of the ones that look like a regular A19 lamp, some of the 800 lumen tri-lobe style and some of the mushroom shaped lamps with the oddly shaped white glass globe over the phosphor dome. I also have a handful of Hue lamps that look almost identical to those.
floobydust:
The LED's are largely cooled by conduction, with the M-core board and glue to the aluminum tube.
But the driver board only gets cooled by convection inside the small chamber, which is pretty much useless obviously. Even if it (driver) dissipated 1W the temperature must be pushing well over 100°C.
IC is BP9916C with CL set to 235mA (2.55R) and ILED 118mA, IC rated max is ILED 200mA.
"The thermal regulation temperature is set to 140°C internally."  :scared:

The light fixtures are a variety, some large glass globes and metal top, like any typical fixture.
paulca:
If you think cramming all that circuitry into the base of a lamp bulb is squeezing things...

Remember a lot of LED bulbs now contain a bi-directional radio and MCU.  Radio either RF433, Zigbee/Zwave or 2,4Ghz Wifi!

The last B27 (UK Bayonet) Zigbee smart bulbs all had no visible circuitry in the bulb, just in the fitting.  I dismantled a broken one (yes I had 3 out of 4 dead within 24 hours of use).  Inside it looked like 240V LED string filaments with just a variable current limiter and a Zigbee radio board mounted 90* on to it.  All within a 2/3" x 2/3".  (Do not buy Innr bulbs!)

The Philips Hue B27 bulbs and the E14 mini-candle bulbs (working fine) show no bulk beyond the tiny little cap, so all over above must fit into the E14 screw housing..  How in hell!
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