These lights are inefficient, don't last long and punch holes in the ceiling causing air to leak to and from the roof space.
Friend Gerald is studying energy efficiency and got me inspired to look at improved lighting for home.
This morning I went out after minimal research and purchased six of these Cree LED star light modules and a 700mA constant current power unit that takes a 12V rail (which I have here on hand) and regulates the current for the lights.
I screwed them all to an aluminium bar which helps to dissipate some heat and of course wired them in series.
They are blindingly bright to look directly at, but overall probably put out as much light as a 40W incandescent bulb. This unpleasant dazzling effect is no doubt because they are such point sources compared to a bulb, they really need a diffuser.
Judging by how hard my 1A meter bashed I'm guessing it's pulling about 1.5 to 2A at 12V so that's up to 24W. Just guessing.
The arrangement I've constructed places them behind my computer screen pointing up to the ceiling.
Overall the effect is quite pleasant and provides light around the computer screen with no glare. Here's how the ceiling looks.
These LEDs cost $20 each, not cheap, the power regulator was $25. Looking at the specs now, I see that I'm driving these LEDs beyond their rated current so I guess their life will be short. The aluminium bar is getting hot.
My guess is that about 20 of these devices would provide reasonable illumination for a work desk.