Introduction: LED Flashlight

Picture of LED Flashlight

A basic LED flashlight is not only a good beginner project to learn about LEDs, but it very useful to have around. In this instructable you will learn how to make an an LED flashlight from scratch. All this circuit requires is an LED, resistor, switch, batteries, and a little bit of soldering. This is a great project for anyone interested in getting started with LED technology or electronics.

To learn more about electronics check out my Electronic Class, and for some practical hands-on information about LEDs, check out my LED and Lighting Class.

For this lesson you will need:

(x1) 1.25" x 6" mailing tube with end caps (or similar)
(x1) 8mm bright white LED
(x1) 10ohm / 1/2 Watt resistor (or appropriate for your LED and power supply)
(x1) LED reflector
(x1) 26.8mm flashlight lens (or similar)
(x1) Pushbutton toggle switch
(x1) 3 x AAA cylindrical battery holder
(x3) AAA batteries

Step 1:

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Solder the resistor the LED's anode (longer lead), and trim away the excess soldered leads from the joint.

Step 2:

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Solder a 6" red wire to the metal terminal on the end of the cylindrical battery holder that has a protruding bump. This side is the positive voltage

Solder a 6" black wire to the opposite end of the cylindrical battery holder. This is the ground side and should have a little round indent.

Step 3:

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Now is time to complete the circuit.

We will start by sliding a 1" piece of shrink tube onto each of the wires attached to the switch.

Once completed, solder one of the switch wires together with the black wire from the LED holder.

Then, solder the other wire from the switch to the cathode of the LED.

Insulate both joints with the shrink tube that had been slid on previously.

Finally, solder this red wire from the battery holder to the resistor's remaining lead.

Step 4:

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Drill (or cut - if using a thin tube) a 1/2" round hole about 1" from one of the edges of the tube.

Step 5:

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Insert the switch into the tube. Pass it up through the hole, and then reassemble it as appropriate to lock it in place.

Step 6:

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Glue the LED to the rim of the reflector using your glue of choice.

Step 7:

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Using a craft knife, cut a 1" hole in one of the tube's end caps.

Step 8:

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Be sure to take any protective coating that may exist off of the flashlight lens.

Step 9:

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Insert the lens into the cap with the hole cut into it, and then use the cap to sandwich the reflector between the lens and the rim of the tube. The lens assembly should now be firmly locked in place.

Step 10:

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Put the batteries into the battery holder, insert it into the tube, and put the other end cap on. The flashlight should now be fully assembled.

Step 11:

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Congratulations on making your flashlight. Keep it handy for when you need one.

Comments

chingada (author)2017-06-19

cool project for sure if you have the materials for free around home , if have to buy it plus time is cheaper to buy one of those 2 for 5 bucks at pep boys with aluminum cases

JeraldC2 (author)2017-06-18

The 10 Ohm resistor value is too low. With 6V battery and a 0.7V drop across the LED, that leaves 5.3 V across the resistor. The current will be 0.53 Amps! That will burn up the LED and the resistor. Power dissipation across the resistor is 2.8 Watt

randofo (author)JeraldC22017-06-19

0.7V is the standard forward voltage for silicon diodes, but we are dealing with LEDs which all have different forward voltages depending on their type and color.

So...

https://www.amazon.com/gp/product/B01CI5P4B4/

This LED has a forward voltage of 3V. The forward current is 250mA. Additionally, the voltage of 3 AAA batteries is 4.5V (not 6V).

http://ledcalc.com/

Using this LED calculator you will see that the circuit requires a 6.8 ohm 1/2 Watt resistor.

Relatively speaking, the 10ohm 1/2 Watt resistor that I am using is well above this.

Nevertheless, I specify in the materials list to use a resistor appropriate to the LED you are using.

cdavenport (author)2017-06-18

6 volts? there are three AAAs. In series that's 4.5 volts. I, too, like the see-thru aspect of your build.

i really like the see through look of this flashlight!

Timothee Gillier (author)2017-05-28

Cool instructable but your main picture doesn't show up.

randofo (author)Timothee Gillier2017-05-28

It is showing up for me.

randofo (author)randofo2017-05-28

Maybe try holding the shift key down and pressing refresh on the browser to do a hard refresh of the page.

Timothee Gillier (author)randofo2017-05-28

Sorry I think there was a bug, but I can see it now.

About This Instructable

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Bio: My name is Randy and I founded the Instructables Design Studio. I'm also the author of the books 'Simple Bots,' and '62 Projects to ... More »
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