Feeding half-wave rectified 12 V AC into the 4 W LED lamp I hung on the end of the halogen desk lamp worked at human scale, but produced dark bars across images made with my Pixel phones. Having solved that problem for the LED lighting on Mary’s sewing machines, I replaced the OEM transformer with a 12 VDC power supply:
The steel lump inside the base is the OEM weight that, in addition to two pounds of transformer, kept the whole affair from toppling over.
The transformer inside the DC supply weighs basically nothing:
The original 12 VAC transformer powered a 50 W halogen bulb and loafed along at 14.7 VAC (yes, RMS) into the 4 W LED. The light is somewhat dimmer at 12 VDC, but not enough to worry about.
Aaaaand the photo bars are gone!
The Smell of Molten Projects in the Morning 
Halgen? :)
in the colonies, they spell it as they say it…
It’s a hard aitch: HCCCCCH·ggnn. Protip: aim toward the spittoon in the corner.
is there a preferred source for those power supplies?
Nah, it’s whatever popped up on eBay when I asked for a 12 V LED driver to match those COB LED strips for the sewing machine. I was mildly surprised the PCB still had parts in all the holes.