You could buy a ledstrip...cheap nowadays. And programmable, nice RGB effects.
It is surprisingly easy to make one yourself. But why?
By making it yourself, you can vary the distance between the led's make it less regular, you can make it double sided or insert two patterns which light up alternately if you reverse the voltage - when the battery is turned around.
If you want more:
With a bit of electronics you can create your own effects.
With a cutter, like the Silhouette, you can make funny shapes with the copper strips.
The Adafruit ledstrips are formidable, but also very "heavy|. This ledstrip with smd led's is very lightweight. You can buy these smd ledstrips at dx, but then again - they have regularly spaced led's...
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Step 1: What Do You Need?
Materials and components:
I bought the led's at farnell.nl:
I bought adhesive copper tape at conrad: (maybe just copper sheet is easier.)
a coin cell battery,
To solder the smd led's you need a good soldering station and a soldering iron with a good tip.
I need a magnifying glass, but if your eyesight is still ok, you could do it without.
For the reversing of the voltage a microcontroller and h-bridge, eg L293NE
Step 2: Prepare the Copper Strips
The copper makes it easy to solder the smd led's.
I bought adhesive copper. To get a strip not glued on something else I glued two copper pieces together (i could have bought copper tape without adhesive layer?).
If you cut the copper in thinner strips, the copper is quite sharp. Not to cut my finger, I made the copper strip flat using some metal box.
The strips can be any width you want.
Step 3: Solder the Led's
The smd led has a direction, because it is a diode, in my case the direcion was indicated at the backside, but also you could see the point was slightly off center. This way I ordered the led's.
The led's are soldered in parallel. The ledstrip can work on a coin cell of 3V.
Every led consumes 20 milli Ampere. This is not much on itself, but the strip has many led's, so for 10 led's 0.2 Ampere, and this can quickly become a lot of current. The coin cell can be exhausted fast.
Step 4: Reverse the Voltage!
You can reverse the voltage by putting the coin cell between the strips in reversed. If you have soldered the led's all to the same direction reversing the voltage will result in all on, all off. But if you have made alternating patterns - with led's in the other direction, two patterns will appear, depending on how you put the battery in:
Step 5: Fantasy Ledstrip
Making other patterns with the ledstrip. And changing the pattern, by reversing the battery.
Of course you must be careful not to solder everything together. There must be a two pieces seperated, so that you can put a voltage on it, without a short cut.
Step 6: Led's on Both Sides of the Ledstrip!
Because you make your own ledstrip, you are in charge! So why not solder it on 2 sides! The led's either on the same spots, front and backside or in a different pattern. And then what about using this reversing the voltage for even different patterns?
Step 7: Reversing the Voltage With Electronics
You can do the voltage reversing more advanced.
Reversing the voltage by electronics can be done with an h-bridge. Also with the h-bridge you can feed the led's more current then the microcontroller can do, because it has an external power source.
Normally you use this chip for reversing the direction of a simple motor.
but it can be used for the ledstrip too.
L293NE or SN754410 is used for the h-bridge, how to connect it and the Arduino script can be found on this page:
or search for h-bridge - arduino. Of course also an ATtiny85 can do this - and is smaller - see the picture with the copper circuit.
The result can be seen in the movie.
The h-bridge also consumes voltage, so you need a higher voltage than the coin cell. In the image the 5V of the Arduino is used as an external source for the led's. This results in a voltage of 2.7 over the led's.
The script can be found at: https://github.com/contrechoc/ledstrip
The Silhouette file for the copper circuit is also added to this step.
Step 8: Application
I used the ledstrips for garments which i showed at the e-textile summercamp in France:
For a few led's you can use the microcontroller - ATtiny85, without the h-bridge. With a Silhouette Portrait, i made special patterns for on this yellow shirt.