Instructables

LED flashlight for under $10 (solderless, flat)

Picture of LED flashlight for under $10 (solderless, flat)
This Instructable will show one how to build a LED flashlight without solder that will lay flat for under $10. The idea for this came from a need to have a flat flashlight that would not roll around when I was working on computers and wiring for my tech support business. Also, I needed something that could be inserted into narrow places, like behind furniture and inside computers. Since I could not find any flashlights that would be able to do these things, I decided to imitate the Free Software/Instructable Communities and build one to my specifications. For the construction of the circuit, many of ideas came from other LED flashlight Instructables on this site. A basic schematic is below.
 
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Step 1: Assemble your parts and tools

Picture of Assemble your parts and tools
stepone.jpg
Many of these parts can be found at Home Depot, Radio Shack and 99 Cents stores.
Parts from Home Depot:
1. One foot of Cat 5 cable (split for 20 gauge wire), Part #: 709489: 27 cents
2. Wood shims, Part #: 091-996-002-0000: $1.09
4. Electrical Tape, Part #: 0-775-78-03-777-6, 59 cents:
5. Light switch, Part #: 078-477-772-713: 64 cents

Parts from Radio Shack:
1. two - 5 mm high brightness white LED, Part #: 276-017: $1.99
2. AAA Battery Holder, Part #: 270-398: 99 cents

Part from Jack's 99 Cent Store, 32nd St. between 6th & 7th Ave, NYC:
1. 2 AAA Batteries: 99 cents
2. One 8.5x11 piece of paper: 1 cent

Tools:
1. #2 Phillips head screwdriver
2. Wire cutter/stripper
3. Scissors
LED-Flashlight.pdf(794x842) 90 KB

Step 2: Connect the battery box to LED

1. Twist the red wire on the battery box around the positive (longer) terminal of the LED light.
2. Take a piece of 20 gauge wire and strip both ends, about 5 inches long.
3. Twist the 20 gauge wire with the stripped end of the black wire from the battery box.

Step 3: Attach the light switch

1. Using the other end of the 20 gauge wire, bend it into a semi-circle, attach it to one of the terminals of the light switch and secure it using the screwdriver.
2. Use a piece of electrical tape to secure the black wire to the 20 gauge wire, which should be twisted around each other.
3. Use another piece of electrical tape to secure the red wire with the longer terminal of the LED light. These should be twisted around each other as well.

Step 4: Complete the circuit

Picture of Complete the circuit
1. Cut a longer piece of 20 gauge wire, perhaps 10 inches and strip both ends.
2. Twist it around the shorter wire of the LED light to connect it. Secure this connection with electrical tape.
3. Bend the other end of the 20 gauge wire into a semi-circle and wrap it around the other terminal of the light switch. Secure the wire to the terminal using the screwdriver.
4. Put the 2 AAA batteries into the battery holder.
5. Turn the switch to "On" to confirm the circuit is functional.
6. If it is not functional, make sure that all of the wires are twisted tightly around each other and that the electrical tape is keeping them together. Also check that the 2 terminals on the light switch are screwed down tightly.

Step 5: Mount the Circuit

Picture of Mount the Circuit
1. Take the 2 wood shims and tape them together using the electrical tape to form a solid wood body. If you would like, you can use duct tape here in place of the electrical tape. Also, if you do not have wood on hand, you can use 2 pieces of stiff cardboard.
2. Tape the 3 sections of the circuit to the body. It might be best to tape the light switch down first, then the battery box with the batteries, then finally the LED light.
3. When taping the LED light down, let it hang just over the edge of the wood.
4. Finally, gently bend the wires to conform to the wood body and tape them down so that they do not hang off the edges. Try to tape them to the top of the wood body.

Step 6: LED hood and final assembly

1. Take the 8.5x11 piece of paper and fold it in half.
2. Fold it in half a second time.
3. Wrap it around the end of the flashlight over the LED bulb.
3. Tape it to the end of the flashlight, with the edge of the paper that is going to be taped down about 1 inch from the end of the wood. This forms a lightweight hood over the LED bulb so that it is protected from damage and also serves to direct the beam.
4. Add extra electrical tape to secure the light switch firmly to the wood body.
5. If you would like, take a piece of 20 gauge wire, string it through the holes in the light switch and secure it by winding it on either end. This will allow you to hang it on a hook for hands-free lighting. Also, you can use a piece of string to create the loop as well.
retzlar8 months ago
this may be a dumb question.. but how do you connect multiple LED lights? I want to have a series of them powered by a switch and AA batteries.
matt392 (author)  retzlar8 months ago
No, it is a good question. I will try to do an Instructable in the future that connects 2 LEDs. I did it in the past; IIRC, you chain them together by connecting the negative wire of one LED to the positive wire of the next one with a wire. But I will have to confirm that for you.
Hi, I just posted a question, looking for help with just such a project as this. If I understand this instructable, I can just get the LEDs, as you have used here, and wire them into the existing AAA circuit, without any sort of resistor? Thanks!
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jsilvers12 years ago
i wonder if u could add a solar panel to this to charge the battery and still have the on/off switch so that u can turn the light when u don't need to use it
marc925 years ago
I believe it would be possible to make this light much smaller to better fit in the places described.
This could be done smaller very easily, with junk computer parts, or just other electronic junk one accumulates. The switch you are using will cause more battery run down than a much smaller switch better suited to the amount of current you need to run an LED.
matt392 (author)  Chiana_Rei5 years ago
One of the design goals was to be able to build it with common, inexpensive parts from retails stores like Home Depot and Radio Shack.
Radio shack definitely sell the simple parts that'd make this project much more efficient
matt392 (author)  lifelong-newbie4 years ago
Keep in mind, part of the design goal was to keep it under $10.  Radio Shack definitely has good parts, but they may have pushed it above $10.
matt392 (author)  marc925 years ago
The size makes it easier to position since something smaller might get dropped into crevices and the like.
ATG marc925 years ago
if 3v button cells r used in serie...this thng can fit into a matchbox...
marc92 ATG5 years ago
With the obvious exception of the light switch