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The "Walluminate"

All > Tech > Hacks/Mods > The "Walluminate" by natetrue

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I first got exposed to the glorious field of illuminating wallets when shooting Gear Live's The Bleeding Edge, a weekly video show. They had been sent the Walit, an electroluminescent glowing wallet, to review. I was excited at the idea - I had personally never thought of a glowing wallet and was eager to see how it worked.

I was, however, completely disappointed. The Walit was terrible. It was dim, the batteries took up too much space, and it had a flimsy clip to turn the light on and off. The very next week, I published an ironically scathing review and presented my solution on the Bleeding Edge, which you can view below:


(If you like The Bleeding Edge, subscribe to it)

You get the idea - a thinner, lighter, more efficient version of the Walit resulted.

A few weeks later, at Mind Camp, Bre Pettis from I Make Things interviewed me and published the video on the MAKE blog. You can view that video here:



Have a look at how I constructed the Walluminate below.

Parts list:
- A leather wallet
- At least four small surface mount LEDs (Search eBay for "white smt leds" or salvage them from an old cell phone)
- Two colors of thin, flexible wire (I used wire wrapping wire)
- Two CR1616 watch batteries
- A small amount of sheet brass, or something to make the battery holder out of
- A 1/8 watt 100k-ohm resistor (though anything betweek 10k and 1 megohm should work)
- A generic PNP transistor
- A small tactile snapdome button

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The first and arguably most important part is to find a suitable wallet. I was given a leather wallet last Christmas which has some great stitching along the top edge on either side of the money hole. It was just the perfect size to slip a few white LED's I'd salvaged from an old cell phone.

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The next step is to run wires from the LEDs (they are kind of hard to solder to) through the wallet's lining. Try to strategically place the wires (as I have) so they don't get bent back and forth very often in the wallet's use. Make sure to use two different colors of wire to keep track of the LED's polarities. I had trouble seeing the markings on the LEDs so I just touched them to the batteries to find out what side was what. Coin cell batteries like the CR1616's won't hurt the LEDs if put in backwards.

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Next comes the assembly of the switch circuit. Since the pushbutton is normally open (if you managed to find a normally-closed button, then you can just skip this whole part), we need a small transistor circuit to invert the signal. Use the diagram below to make sure you've got everything wired correctly.

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The circuit design is very simple. When the wallet is closed, the button is pressed, pulling the base of the transistor high. Since there is no bias between the base and collector of the transistor, the transistor will not conduct. The only current usage is through the 100 kilohm resistor. By my estimates it will take about 5 months to drain the lithium batteries from this current alone.

When the button is released, the base is pulled low, biasing the collector-base junction of the transistor. Current to the LEDs is switched on and the LEDs take what they need from the batteries, illuminating your money in the process.

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