3 ms·
LED bulbs usually use the most basic of power supplies, the capacitive dropper[0], the downside is that they tend to die easily. Also, the LED diodes themselv
by NikkiA 4y ago
LED bulbs usually use the most basic of power supplies, the capacitive dropper[0], the downside is that they tend to die easily.
Also, the LED diodes themselves will often be multiple in series (a string), or series-parallel (several strings in parallel) depending on the bulb, that end up needing more than just 2V, anywhere from 12V to 60V or so per string of diodes.
Sometimes the high power diodes being used are themselves a series chain of diodes on a singular piece of silicon encased in a blob of phosphor, so that the diode package ends up needing 12V or so. These are often referred to as 'COB' diodes.
(apologies for the RAS syndrome, but saying 'LE diodes' or just 'LED' to refer to the individual light elements when talking about 'LED bulbs' is too confusing otherwise)
[0] https://en.wikipedia.org/wiki/Capacitive_power_supply https://en.wikipedia.org/wiki/Capacitive_power_supply
- djmips 4y agoHow about. "Also, the LED elements will often be in series (a string)"
- rcxdude 4y agoRAS syndrome is not a bad thing for exactly the reason you've just mentioned! redundancy is common in language, it does actually serve a useful purpose and this particular redundancy confuses no-one.
- userbinator 4y agoCapacitive droppers are the most reliable for LED bulbs in my experience, because they are very simple and there's not much to go wrong. It's usually the IC-based ones that die first.
- comboy 4y agoJust to add a data point, I have the opposite experience based on just a few bulbs of different brands I disassembled over the years.
- userbinator 4y agoWhat has failed in them?
- NikkiA 4y agoIn my experience, it's usually the capacitor that pops, but my experience is mostly with GU10 form factor bulbs, which have the downside of being very compact and fitted in fittings that don't have good heat reduction properties resulting in everything running hot, even in a LED bulb that should be cool. Even the cheapest LEDs last longer than standard halogen GU10 bulbs though, so there's that.
- lightedman 4y agoCapacitor usually blows - they don't like operating really hot and heat removal inside those small form factors is a serious challenge. Also, many times, the whole power converter is encased in a semi-insulative rubber, so that just compounds the problem.