Picture of The Most Basic LEGO 9V Flashlight.
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There are lots of 9V flashlights instructables. Mine only takes advantage of the perfect fit of 5mm LEDs in the holes of the pieces of the classic brick of LEGO and the fine and "I paid for it" look of the brick.

Also thanks for the ones explaining how to reuse the connectors of exhausted 9V batteries.

Thanks for your time!
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Step 1: Elements:

Picture of Elements:
You need:

1  2x4 plain brick of LEGO
1  2x4 "normal" brick of LEGO
3  5mm 3V LEDs
1 Connector of an exhausted 9V Battery

You may (will) need a solder an lead.

Of course you need also a working 9V Battery...

Step 2: Drilling the Holes.

Picture of Drilling the Holes.
Sinply drill the holes of the brick. This will house the LEDs. Finish it whith a dremel's trimmer

Remember that theLED s must be 5mm dia, exactly the inner diameter of the factory brick's holes.

Step 3: Trimming the inside.

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You need to trim the inside of the brick to make room for the bottom part and the pins of the LEDs

Step 4: Soldering.

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Now you can cut, bend and twist the LEDs' pins and... solder it.

You must connect it anode to catode; if you don't know, simply try and try until they light..

I didn't use resistors because 3V (white) LEDs can work even at 4,5V so there is no fear.

One more thing: You must insulate contacs, with tape or paper as I did, leaving the main contacts out.

Step 5: Contacts and finish.

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Drill and trim the 2x4 plain brick to house the contact of the old battery.

Mount the block one way and try the other if it not work. LED's will not be fused if you mistake.

And it is done!
jjone5383 years ago
Great! This is Awesome We need more cool lego projects like this
skolsox3 years ago
Even simpler than that, many legos come predrilled with those three holes, and 9volt leads are cheap at radioshack, great instructable though
skolsox3 years ago
Even simpler than that, many legos come predrilled with those three holes, and 9volt leads are cheap at radioshack, great instructable though
splazem4 years ago
Sweet! You should put legos around the battery.
Thats what I was thinking as well. You could assemble a whole flashlight out of legos - easy to open up and pretty cool. Im going to try this when Im back home :D
What a cute idea! And totally useful too, I mean do you know how easy it is to get your hands on a 9v and how long leds last--- no wait you probably do but still.
chipper354 years ago
While the language could use a little touching up in places, this is an excellent instructable!!
leds use 1,7 volts, x3 = 5.1 v , you should put a small resistor of around 160ohms in series with your circuit just so a full battery dont kill your leds
infob (author)  pbergeronronronron4 years ago
LED voltage depends on LED's color, from 1,7v for red, 2,6v for most colors and 3,5 for white and blue.
Take a look at
If I would find 1,7v WHITE LED I would use them in a Maglite Solitaire, intead the LED which is sold in 6$, and save money.
Thanks for your attention, anyway.
chuckr44 infob4 years ago
4 years ago I made LED flashlights. Red LEDs took 3vdc, super bright white LEDs needed 5vdc each. Has this changed?

That is why my first projects were to convert 2 cell (3v) regular flashlights into a single red LED, no resistors needed, just simple wiring and stuff that LED into the screw in bulb base.
infob (author)  chuckr444 years ago
May be that red led was a white one with red plastic, instead of actual red leds with clear plastic?
Anyway, the torch works. What is more, I made another 9V one (without lego) with three pairs of leds, which means each LED takes 4,5v and they don't burn but ligh a lot.
chuckr44 infob4 years ago
I'll be darned. The wikipedia page above was modifed just yesterday. Red LEDs really did come down to 1.7vdc.
My kids will totally get a kick out of this.
mischka4 years ago
Simple and nice. I like it