Building Active Grains
When on the road it is difficult to achieve sufficient lighting conditions, because often it is impossible to carry all needed material (professional photo-lighting) with you. This little tutorial shows how to build active (e.g. battery-driven, light emmiting), grain-like objects out of cheap materials. They are designed to be used in dim to dark areas using back-face vision through a glass desktop.
- see-through film-box (PET)
- battery (Lithium 3V / 2 Pins; Renata - CR2032 FH-LF)
- adhesive label
- little piece of styrofoam
- resistor (0.25W 1% 120R)
- jumper (2,54mm; Fischer Electronik - CAB 4 GR)
- jumper base
- LED (5MM clear, red; Vishay- TLDR580030)
HousingCut the film-box with a sharp knife that you get a box of an approximate height of 1.5 cm. Cut a hole into the cover, such that you can easily stick the jumper through it.
If you build several grains at once, you may want to use the removed part as a marking template for the other boxes.
LiningUnpack the battery. I bought mine at farnell; they packed them one-by-one in a plastic bag, placed on a piece of styrofoam and jacketed with an adhesive label. Cut out a roundish form from the styrofoam (which is approx. 0.7cm thick) slightly bigger then the diameter of the film box and press the LED into the center to get a hole.
ElectronicsSince the battery is not placed on a breadboard, and the wiring will be wrapped around it, it has to be isolated. I used the adhesive label of the packed battery for this purpose.
Bend the wires of the LED on their very shortest point apart from each other. Then, replace one wire with the resistor component. This way, the resistor is in place and you do not have to worry about it anymore. Place the LED on the battery side with no soldering lugs. Bend the LED-wires around the battery, before soldering, test if you solder it to the right lug! Solder one wire to the middle lug, the other to the jumper base. Solder the second contact of the jumper base to the batteries rim lug. Test your work by shortening the contact by placing the jumper on its base.
Putting it all togetherPlace the film-box cover on the battery, and the styrofoam-wheel on the LED. Then put it all into the film box.
You're all done.