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0 pointsxxs2y ago0 comments

The same topic about LEDs has so many entries on HN in the recent years. I have posted about it a lot. To add to the list

  - low power factor (usually 50%).
  - cheap passives, caps/coils
  - terrible heat dissipation, e27/e14 are no good target, but see overdriven again
  - close to no input protection (see power supplies, again), so motors totally wreck them with their induction kickback

OTOH, constant (not over)driven LEDs with dedicated power supplies (pref. isolated, so safer), with decent area, aluminum PCBs can last long.

A cheap advice if you have to buy a retrofit LED bulb, buy the heaviest one, i.e. get a scale with (at least) gram precision and weight them. More mass - better heat dissipation, better passives.

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droopyEyelids2y ago

We're mostly on the same page, but there are some caveats to buying the heavier bulbs, even assuming the weight is all heat sink- because that won't matter if the heated air has no where to go!

An expensive bulb with a nice heat sink will fail just as quickly as a cheap one when you put it in a well-sealed can light or something else that traps all the hot air.

xxsOP2y ago

If one bothers to care about heat sinking, they might actually test the thing and opted not overdrive it. It's just a good totally layman indicator.

Funny enough most mains/350V DC, chips tend to have a limiting resistor for the current drive - lower resistance = high current. Most (if not all) have two resistors in parallel (for a better control, and less power per resistor) - desoldering one would greatly improve the lifespan for a minimal luminosity loss. So by picking a larger heatsink, they might picked a bit large value for the resistors as well.

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