Wow using a dashed stroke on circle is a brilliant idea! Set the stroke width to be similar to dash width, and set stroke miters to be round.
Another way is to use clones. Create one "light" on the side of the knob, and drag it's rotation center outside, to the center of the knob. Then use Create Tiled clones... option, 1 row, 15 columns, Shift X per Column -100% (this is because Inkscape creates clones one next to each other but you need yours on top of one another), Rotation per Column 15°, leave the rest of the options intact. Hit Create
