Ultra-thin USB powered light box

Originally published at: https://boingboing.net/2019/11/20/ultra-thin-usb-powered-light-b.html


Just a word of warning: these have either no or poor over-voltage protection. Store them unplugged.

We bought a few to have around lab (I’m a physicist that studies squishy stuff). A student left one plugged in over a 1 week vacation and the battery swelled up and split the case. Luckily we noticed and unplugged the thing before something more exciting happened.

That said, we immediately bought more. They aren’t nearly as bright as more expensive light boxes, but are impressively uniform, and having 3mm-thick, cordless lighting gives us incredible versatility. They’re great!

From what I understand, they were originally marketed towards quilters?


Oh wow, if I still did physical work on a regular basis that would be pretty sweet.

These days I find that my very occasional lightbox needs can be fulfilled by filling my tablet’s screen with white and setting the brightness to maximum. I’ve even used this as a way to enlarge a sketch: photograph it, zoom in, and put paper on top of it.


I wrote to Wacom to suggest that they add something like this to their Bamboo graphics tablets, although it might be nice on other ones too. My “avatar” if it shows up, was made by scanning and tracing a photo of myself and then coloring it… and it would have been easier if I could have done the tracing right on the tablet.

If you want a build-your-own version, pick up the howto here:

I made myself one from a broken laptop display, obtained for free from a laptop service shop. (I got a stack of them.) The backlights are pretty good for this purpose. The rest was replacing the LCD panel with a cut-to-size piece of 2mm glass, and making a chain of SMD LEDs with appropriate resistors, fed from 12 volts. (A 5V version for USB or phone charger power could be doable too. That one could be also powered from a power bank, for portability.)


The big ol’ iPad Pro should be a pretty nice, if not exactly cost-effective lightbox.


You can make one from a cracked or otherwise decommissioned large monitor or flatscreen TV. With a bit of luck the backlight may still be working, eliminating the need of replacing it. Some of the power supply boards even have descriptions of the connector pins on the silkscreen so without major reverse engineering you can attach a switch for powering it on, and optionally a PWM circuit for regulating brightness.

(If you have to do the reversing, most of the pins are outputs, connected directly to those big-ass caps in the PSU outputs (these caps die often and are the primary cause of such screens’ decommissioning, so you can easily score a free monitor), and the higher-current ones can be several connected in parallel. That look-and-see will eliminate most of the pins. Then you get one that goes to the high voltage part of the PSU, where the backlight power is generated for the CCFLs, one that enables the high power part of the PSU (there’s a low-power that provides standby 5V), and maybe one or two others. You’ll need to connect the latter in a way that enables the PSU, and then attach the backlight control one(s) in a way to light up the CCFLs.)


They are high on my list of wants. Unlike Trump, I want a light box.

I think this can happen with anything with a litium-ion or LiPo battery. I’m not sure it’s related to overvoltage or just the battery breaking.

I’ve had this happen to mifi router, which had been in constant use for about 4 years and then suddenly the battery started swelling. I replaced the battery and have been using the same thing for 2 years since without problems. So my theory is the problem is something breaking in the battery (or the batterys internal electronics) and not really the device itself.

I pretty much don’t really have another option than letting the mifi plugged in all the time, because plugging it in/out every 2 hours is too much of a pita, but the thing does worry me. Lithium batteries are scary!

So just a warning that this can happen to well made electronics as well (I think you can call the mifi well-made, as it has been in 24/7 use for about 7 years now).

I have one of these but generally I found them too dim to send enough light to the paper thickness I use.

I made myself one with a decomissioned university transparency projector. It is a bit clunky but works well with my preferred material :slight_smile:

Batteries in general are born to die; and Li-ions are more likely than average to take out their rage RE: the electrochemical condition on bystanders in the process; but the quality of the charging circuit can make a definite difference.

Among well-designed devices having the battery puff up alarmingly and/or pour forth a bounty of probably toxic smoke is a sign of a fairly serious defect in the battery. Among devices that are poorly designed or just plain negligent the odds are much higher that the charging circuit is actively murdering the battery by subjecting it to charge conditions its spec sheet very clearly warns you to never subject it to (do li-ions appreciate being trickle charged after full just because lead acid tolerates that? Nope.)

All that said, had a rather dramatic case last week from a device that, I suspect, falls into the ‘properly designed’ category(at least in terms of charge circuits, other aspects are a matter of taste). A user sent me a picture of their Surface Pro 4, asking why the display was curving on one side.

It turns out that, when you have a swelling battery pouch sandwiched between a more or less unyielding metal chassis and a rather more yielding LCD; the LCD is what starts to give. The pressure was strong enough to defeat the adhesive between the LCD and the SP4 chassis(not a trivial procedure) and ended up opening a ~1cm gap all across one side.

Luckily we got all their files off and them transferred to a new system while the old one was still in the ‘ominous chemical odor’ stage and were then able to unplug it and never plug it in again to avoid the ‘compellingly vivid crimson jets of flame’ stage. (You don’t want it to be coming out of the device you are using; but lithium gives fire a gorgeous hue).

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