DIY Waterproof Flashlight

Introduction: DIY Waterproof Flashlight

About: 31 years old tinker and diy hobbyist. From Oulu, Finland. IG @mkarvonen_instructables

The cheapest 100% water/dust-proof flashlight. Made entirely out of household objects.

In this tutorial i will show how to make one.

The flashlight will use the simplest electronics available. So basically it is simple enough to be a survival lamp also.

The basic idea for this was that it has to be waterproof and it has to stand up on its own so that it's possible to work at the same time and you don't have to hold the lamp at the same time.

Step 1: Right Materials and Right Tools

The material list is simple.

Simple PVC pipe. Mine is an 50 mm wide and it has got a 90 degree bend on it.

One piece of stopper for the pipe. (that piece that comes in the bottom end.) Also 50 mm wide.

Some wire between the lamp and a battery.

One 9 V battery (6LR61) and a connector for the battery.

One SMD LED lamp. This one is made for a normal household lamp.

That's about it. It can be done straight from those with only your bare hand's.

But today is not survival day one and i happened to have some tools.

Tools i used to make this were:

Hot glue (gun).

Side cutters.

Soldering iron.

Electric tape.

Spray paint ( Optional)


Step 2: Painting (optional)

I had some old and many times frozen spray paint bottles. So i decided to test that will they still work.

The color i chose was green since i will use the lamp mostly when i'm outside.

The paint was OK. Tough it is about 2 years old and was frozen several times in that period.

After painting let's start working on the electronics since the paint takes time to dry.

Step 3: Choosing the Lamp and Dissasemply.

It's important to use LED or SMD LED lamp for the project. Since the lamp uses only 12 Volt or lower direct current it is obvious that the lamp has to include a transformer.

I opened the second lamp just to see what is inside all of that.

There is an small SMD LED, 2 wires, and a transformer at the end. All the aluminium parts work as a heat sink.

But i had an another lamp of the same made. This time its time to open the lamp without breaking the targeting class.

Using a hacksaw to pry open the lover plastic case the transformer is revealed. Cut the two wires going to the led element.

Then clean up the rest of the aluminium case and peel the two wires in there.

These wires are for the LED's anode and cathode. At this point it's not relevant witch is witch. let's catch up with that later.

Step 4: Waterproofing the Lamp.

This sealing process is just for this lamp. There could be lamps that don't need this step.

The lamp has got those small holes around it. To make it waterproof the holes has to be filled.

Hot clue is the answer. Hot glue runs well and sets up quickly and fills the holes so it wont leak.

Remember that the LED need's a heat sink or it will burn out.

The clue does not modify the heat sink's heat disposing functionality in this use.

Remember also that the LED is driven with 9 Volts instead of 12 Volts so it will generate a lot less heat.

Step 5: Soldering the Wires to the LED.

Cut two wires for length of 15 cm. Peel the cables and solder them to the led's own cables.

After soldering the wires use some electric tape to cover the wires.

To help the soldering you can dip the cables peeled copper in tin to make the connection easier.

Step 6: Anode to Anode and Cathode to Cathode.

The most simplest way to test led's "legs" is to just plug the battery on to it.

LED = Light Emitting Diode.

If it is a diode it wont burn or damage the component if the battery is the wrong way around. This is called blocking direction.

If the battery is the right way around the LED will light up.

In this case you wont have to think about using resistors. The optimal voltage to the LED is 12 Volts. If your battery is above that i suggest getting a smaller voltage battery. Like in my case the battery voltage is bellow 12 Volts so resistors won't be necessary.

Solder the battery connector to the cables. Remove battery before soldering.

Use electric tape to secure the cables so you don't have a shortcut.

Step 7: The Assembly.

At this point the paint should be dry. If not, let it dry first.

Push the cables through the pipe. Seal the lamp with hot glue if needed.

Put some bubble wrap or something that fits your imagination to secure the battery in place.

Connect the battery to the battery connector and push the bottom stopper in place. It will be so tight it wont leak in any situation.

Enjoy your powerful, cheap, water/dust-proof lamp.

The main reason it hasn't got any on/off switch is that any holes in the case are more holes to leak in sometime. The bottom stopper is easy to remove for operating the lamp's light.

In the fifth picture you can see that the LED uses about 70 mA and the battery has got 300 mAh so the light will burn bright for 300/70 = 4.23 hours.

Step 8: Looks of the Lamp.

As i mentioned the lamp should be standing on its own.

Light is bright as it was when it was in use as a ceiling lamp.

See the last two step's to see how it did on two main tests.

Step 9: Light Test.

First picture is the view without the lamp. And the last two are taken with the lamp.

The light test is.....


Step 10: Waterproof Test.

The test was done in normal sink. The water was about hand temperature.

The lamp floats so it is good for fishing also. I had to push it under the water to see if it was waterproof.

The waterproof test was....


If you liked my project remember to comment and subscribe!

Follow me to the world of projects. There is a lot more to come. ;)

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    7 years ago on Introduction

    This looks great. My only suggestion would be to add a waterproof switch. I know you address this, but most waterproof switches come with a rubber gasket insert to stop leaks around the switch itself.