Total cost: 5 INR (less than 1$)
1. We need simple circuit which can make LED glow. This can be done by connecting two wires to 2 teminals of LED and then to Battery.
2. You can simple add one switch which will make them turn ON/OFF
3. Assemble everything inside your wallet
This makes simple LED glowing inside your wallet .... Nice and easy. But, dunn you think its very boring ? I mean making swich ON/OFF everytime ? and that is not techie at all !
OR we can make it automatic i.e. whenever you open your wallet light should glow and whenever you close light should switch off.
Hows that sound ?
Well, we will hook up two safety pins inside wallet. We will connect wires from LED to these pins. These pins are hooked in such a way that, they will NOT touch each other when wallet is closed (due to folding).
Once we open wallet, these pins will touch each other and circuit will complete and making LED glow.
Problem ... Do you think, every time you open wallet pins will be aligned automatically ... Maybe yes if you are fixing it ... bit there is one more simpler way ...
What If we make that couple come close to each other, by some natural force ;) ... Yes, we can use Magnets :D ...
The pic says it all ...
very simple, cheap but useful