How to make a tiny, thin LED flashlight?

[John Jones]

I'd like to stick a tiny LED onto a strip of card to make a flashlight that doubles as a bookmark, allowing me to read wherever I am!

The LED can be white or red, but must be nice and bright (I may use more than one). Plus it all has to be light and thin.

My electronics knowledge is poor and I'm not able to solder. Can I simply buy the parts and hook them up? What would I need? I've seen small LEDs on sale but no idea which type I'd need, how to power them, or how bright the light would be?

Please help!

 

[Buk]

Your starting point may be the power source. The thinnest common batteries are the CR2012 20mm x 1.2mm which has a 5mAh capacity and a discharge rate of 0.1 mA; and the CR2412 24.5mm x 1.2 mm which has a 100 mAh capacity and a 0.2 mA.

Both are 3V, and 3V * 0.1A / 0.2A gives (at most) 0.3W/0.6W of light. Is that enough (for you) to read by? And how much reading will you get per cell?

 

[John Jones]

Thanks Buk, great advice. I do want it nice and bright so it can be used as a general flashlight, I would say at least 1W, ideally more. I won't be using it for long periods. I don't mind it being a little thicker, maybe 5mm wide, I can still slide that in a book.

 

[Pommie]

1W is total overkill. Most modern LEDs are very bright when run at 20mA. I normally run them at about ¼ of that (5mA) so 2V at 5mA = 0.01W.

The CR2412 mentioned by Buk can supply 0.2mA so I'm not sure how long it would last at 5mA - maybe 20 hours - maybe less.

Mike.

 

[augustinetez]

You might want to do a search for 'LED bookmark' as what you want is readily available for less than it's going to cost to build.

This is one example (no good as a general flashlight though - probably asking too much on that front within your described constraints) Ultra thin LED bookmark

 

[John Jones]

Thanks for the replies guys!

1W is total overkill.

Oh OK, I don't have much experience with LED wattage and it's hard to gauge how bright they are.

You might want to do a search for 'LED bookmark' as what you want is readily available for less than it's going to cost to build.

Thanks so much, that is brilliant and I will definitely order one of those as well.

But I do have my own custom bookmark in mind, it will be customised in other ways including the print, plus I'd like to be able to use it as a flashlight, not just for reading.

So I'd still like to know how I can construct a simple LED and switch... could I hook up a few parts without needing to solder!?

 

[augustinetez]

could I hook up a few parts without needing to solder!?

Well, if you want something thin for the bookmark, that will mean using surface mount components and they don't have wire leads so need to be soldered.

You can get some switches with screw type connections but they are usually large and bulky switches.

It is more than likely you will need to solder to do what you want - there are conductive glues but I have no experience of these, somebody else might like to chime in about that.

 

[John Jones]

Thanks everyone for the help. Now I know that products like this already exist I've decided to just buy something, there seems to be plenty of retail choice. Those LED bookmarks are pretty close to what I need, or I may rip out the internal components of a small retail LED and attach it to my own construction. Thanks for the help!