LED Light Bulbs Running Directly from Wall Current?

[DrDeke]

I moved recently and found some light fixtures in the new house with "candelabra base" (smaller than the normal light bulb screw connector) sockets containing incandescent bulbs. I replaced these with some "classic filament" style LED bulbs that I bought at a local retailer, and noticed that the new bulbs have a pretty strong strobe/flicker effect when in use. This got me wondering about what kind of driver circuit these bulbs had, but when I took a look, it appears that they don't have any kind of driver or power supply circuit at all, and that the LED elements run directly from wall current!

I have been seeing these "filament-style" LED bulbs quite a bit lately but have no idea how they are made or how they work. The light emitting elements look like relatively long strips; are they actually a bunch of LED junctions in a long strip? If not, any idea what they are?

Here are a couple pictures of the bulb in question in case my description wasn't clear:




Cheers,
Rusty D.

[Zero999]

I don't think they run directly off wall current. There will be a tiny capacitive dropper circuit integrated into the base. The filaments consist of many little LED dies in series, so the voltage can be relatively high and current low.

[kalel]

There are a lot of tiny LEDs in there, running on relatively high voltage.

There are all kinds of variants.

Here is one:
https://youtu.be/NffhdAz9pc4?t=559

The circuit is in the base in this example.

[boffin]

I suggest looking at some of Big Clive's videos on filament LED bulbs

[kalel]

I suggest looking at some of Big Clive's videos on filament LED bulbs

Definitely. I linked one above, but there are multiple videos about it, and many about LEDs in general.

[IanB]

Whether LED lamps flicker depends on the quality of the design. Some are better designed than others. I recently bought some of the same style of lamp and they seem fine to me, no observable flicker. They also claim to work with dimmers, though I haven't tried this.

[Zero999]

Whether LED lamps flicker depends on the quality of the design. Some are better designed than others. I recently bought some of the same style of lamp and they seem fine to me, no observable flicker. They also claim to work with dimmers, though I haven't tried this.

I would have thought that LEDs which don't flicker, will have a larger base than those which do, as more room is required for the filter capacitor.

[IanB]

I would have thought that LEDs which don't flicker, will have a larger base than those which do, as more room is required for the filter capacitor.

Seems logical. My lamps have the standard base, not the miniature chandelier style. In fact, I am not sure how you can fit any electronics at all in a miniature base. Maybe the OP is right that there is nothing in there?

For example, suppose you put about 30 LEDs in series with a small dropper resistor. You could put this string directly across the mains supply and they would self-rectify and need no additional circuitry. They would obviously flicker noticeably as they would only be lit up every half cycle. Maybe this is what the OP's lamp is doing?