# The Universe of Discourse

Mon, 28 Feb 2022

### Why?

You might do this because you have trouble seeing.

Or because you find you are more productive when the room is brighter.

Or perhaps you have seasonal affective disorder, for which more light is a recognized treatment. For SAD you can buy these cute little light therapy boxes that are supposed to help, but they don't, because they are not bright enough to make a difference. Waste of money.

### Quirk's summary

Quirk says:

I want an all-in-one “light panel” that produces at least 20000 lumens and can be mounted to a wall or ceiling, with no noticeable flicker, good CRI, and adjustable (perhaps automatically adjusting) color temperature throughout the day.

and describes some possible approaches:

Buy 25 ordinary LED bulbs, and make some sort of contraption to mount them on the wall or ceiling. This is cheap, but you have to figure out how to mount the bulbs and then you have to do it. And you have to manage 25 bulbs, which might annoy you.

Quirk points out that 815-lumen LED bulbs can be had for $1.93, for a cost of$2.75 / kilolumen (klm).

Another suggestion of Quirk's is to use LED strips, but I think you'd have to figure out how to control them, and they are expensive: Quirk says $16 / klm. ### Here's what I did that was easy and relatively inexpensive This thing is a “corn bulb”, so-called because it is a long cylinder with many LEDs arranged on in like kernels on a corn cob. A single bulb fits into a standard light socket but delivers up to twelve times as much light as a standard bulb. powerCostLuminance (W) (lm) (bulbs) 25$22 3000 1.9
35 $26 4200 2.6 50$33 6000 3.8
54 $35 6200 3.9 80$60 9600 6.0
120 $80 14400 9.0 150$100 20250 12.7

The fourth column is the corn bulb's luminance compared with a standard 100W incandescent bulb, which I think emits around 1600 lm.

Cost varies from $7.33 / klm at the top of the table to$4.93 / klm at the bottom.

I got an 80-watt corn bulb ($60) for my office. It is really bright, startlingly bright, too bright to look at directly. It was about a month before I got used to it and stopped saying “woah” every time I flipped the switch. I liked it so much I bought a 120-watt bulb for the other receptacle. I'd like to post a photo, but all you would be able to see is a splotch. The two bulbs cost around$140 total and jointly deliver 24,000 lumens, which is as much light as 15 or 16 bright incandescent bulbs, for $5.83 / klm. It's twice as expensive as the cheap solution but has the great benefit that I didn't have to think about it, it was as simple as putting new bulbs into the two sockets I already had. Also, as I said, I started with one$60 bulb to see whether I liked it. If you are interested in what it is like to have a much better-lit room, this is a low-risk and low-effort way to find out.

Corn bulbs are available in different color temperatures. In my view the biggest drawback is that each bulb carries a cooling fan built into its base. The fan runs at 40–50 dB, and many people would find it disturbing. [Addendum 20220403: Fanless bulbs are now available. See below.] Lincoln Quirk says he didn't like the light quality; I like it just fine. The color is not adjustable, but if you have two separately-controllable sockets you could put a bulb of one color in each socket and switch between them.

I found out about the corn bulbs from YOU NEED MORE LUMENS by David Chapman, and Your room can be as bright as the outdoors by Ben Kuhn. Thanks very much to Benjamin Esham for figuring this out for me; I had forgotten where I got the idea.

[ Addendum 20220403: Gábor Lehel points out that DragonLight now sells fanless bulbs in all wattages. Apparently because the bulb housing is all-aluminum, the bulb can disspiate enough heat even without the fan. Thanks! ]