silly circuit

It's an AC Chip-on-Board (COB) LED filament. After a lifetime of using a resistor to carefully control current through an LED to keep it from burning up, it sort of shocked me, so to speak, to see an LED directly connected to Line and Neutral.

What are CoB LEDs?

LUXEON CoB Finder

A CoB LED (or chip-on-board LED) is a single device with many LED chips mounted on a thermally efficient substrate placed below a uniform phosphor coating.

Anyone who walks through a store or home with recessed or track lighting likely experiences light from a chip-on-board LED (CoB). CoBs are widely used because they emit a bright white light output from a compact light source and are very efficient in a broad range of applications.

So what is a CoB LED, and how is it different from other types of LEDs?

CoB (chip-on-board) refers to the way in which the LED unit is constructed. The basic elements of white CoB LEDs are:

An electrical power supply to provide the energy to drive the LED The light-emitting chip or ‘die’. This is sometimes referred to as the blue light pump, and is made of a semiconductor material, indium gallium nitride (InGaN), which emits blue photons when energized. A phosphor coating which converts the blue light to white. The chemical composition of the phosphor is controlled to produce light of a specific color temperature. <excerpt>

The onsemi chip is little more than a depletion FET. Assuming this lamp has custom silicon I'd expect it to also be a depletion FET. Or if it's a low end device possibly just a resistor. If he looks at the supply waveforms he should be able to figure it out.

That high voltage NUD devices work quite happily connected direct to live and nuetral. There are a boatload of similar parts available since LED's became a thing in car front/rear lights.