:blob_facepalm: realized I missed something incredibly obvious when thinking about lava lamp usb power design. As a reminder the halogen bulb will draw ~4.1A @ 12V DC Fundamentally I need to do two things: limit input current to below 3.1A (for usb-pd 65W) control bulb power between >40W and 0W using a pot knob (or eventually maybe analog feedback circuitry). For some reason I'd been thinking of those as two different tasks, like buck regulate the voltage down to 12V and then mosfet-pwm the intensity or something. But they're not, they're the same job. The bulb doesn't even care if it gets 15V or 20V as long as I respect its power rating. Alls I need is a buck regulator with output current feedback. I can literally use the same power circuit from the plasma donut with modified min/max limits.