A Light to Charge By?

February 10, 2008 9:37 AM

How do I light the inside of a box? Cheaply. Efficiently. Blue-LEDly. AC 120ly.

I made this box and shelf to hide my cellphone charger brick and to have a convenient place to stow the phone.

I wired a switch into the extension cord and I'd like to wire the light into the same cord so that it can indicate when power's on and when power's off. Space is tight in the box (it's 2 1/2 X 2 1/2 x 11 1/2) -- there's room for another thin brick and not much else.

I've googled and etc and the results haven't been bright. So far my options appear to be 1) wire the LEDs myself (which is beyond my electrical know-how); 2) stuff something big in there (which is beyond the capacity of the box).

Any bright ideas?

posted by notyou to home & garden (7 comments total)

Wiring LEDs isnt so bad. Get a powersupply that'll kick out 5volts and a couple of resistors.
posted by damn dirty ape at 9:41 AM on February 10

It's not so difficult to wire LEDs to AC.
posted by themel at 10:12 AM on February 10

Erm, wire LEDs to AC.
posted by themel at 10:13 AM on February 10

If you're flexible about your requirements, I've seen some really flat night lights with a nice blue glow. They only stick out about a quarter inch.
posted by advicepig at 10:18 AM on February 10

Building on advicepig's suggestion, those nightlights would be excellant for you because there is nothing inside them - the flat glowing sheet (called EL, or electroluminescent, sheet) has two connectors that just wire directly to the two AC 120V wires. No components needed, just the EL sheet out of the nightlight connected to your AC wires. (Note, if you buy a nightlight that only turns on when it's dark, that will have extra components that might make things more complex, but the cheaper ones have nothing in them, so they'd be perfect.)
posted by -harlequin- at 4:27 PM on February 10

Just like to point out that the circuit themel links to has long been considered dangerous. So long, in fact, that I can't find a reference explaining the danger on the internet, and the latest handbook I can find that recommends the design is 20 years old!

Fundamentally, the problems are that the full mains peak voltage appears at the LED, and that the series capacitor needs to be rated not only for peak mains voltage, but needs to comply to the relevant safety standards in your jurisdiction for leakage, ESR, punch through, failure mode, etc.

Yes, it works; no, it's not considered safe.
posted by Pinback at 5:48 PM on February 10

Yeah with electronics you should really buy a pre-made power supply like I suggested and work off of that. You can use my link with a blackberry charger and get 5volts out of there relatively safely. You dont ever want to be touching the mains.
posted by damn dirty ape at 8:25 PM on February 10