Intro: DIY 9 Volt LED Emergency/Backpack Flash Light
Just what you need for an emergency or a camping trip! It's small, it's bright it runs off one of the most common and versatile battery's around the 9 Volt. You can switch it on and off and its so small you can fit it any where. You can carry it every day and doesn't weigh much in your pocket or pack plus it is super efficient! Its the perfect Emergency/Backpack LED Flash light!
Step 1: Parts You Will Need for This Project!
1: You will need two 9 Volt battery's one good one and one dead the dead one is a parts donor.
2: You will need one 9 Volt battery top.(see picture parts donor 9 Volt)
3. You will need one 9 Volt battery bottom.(see picture donor 9 Volt)
4. You will need 3 wires one black one red and one copper wire. (see picture each one about 2" in length)
5. You will need one small but strong magnet.(see picture)
6. You will need 3 white LEDs.
Step 2: Tools You Will Need for This Project!
1. You will need a Push Pin (Be careful! It is Sharp!)
2. You will need some solder (Use the stuff with out lead)
3. A soldering iron. (Be careful! It is hot!)
4. Wire strippers (You could use a razor blade if you don't have wire strippers but be careful! don't cut yourself)
5. Hot glue gun and glue. (Be careful! It is hot hence hot glue!)
6. Small screw driver to pry open the battery(Be careful! Don't stab yourself!)
Now that you have been warned of all the hazards! Don't blame me if you do something dumb!
Pro tip: Use wacky tack poster tack to hold your parts in place for assembly. (Don't eat this!)
Step 3: How to Find Parts for This Project!
To find a good parts battery, I use my old smoke director battery's that I replace each year. They work great for parts and some times they work for the flash light too and will power it for weeks or a month.
Here is a good look at some common 9 volt battery's and what there is in them for you to salvage. I like the Duracell's! for the donor battery.
As for led's you can find them every where I got mine from a broken 4' led replacement T8 light bulb. You can find them in McDonald's toys, light bulbs in the house, key chain flash lights that people toss when the button cells die. You can find them in old sidewalk led lights is a good source.There all over the place take a look around.
Step 4: How to Pry Open a 9 Volt for Parts
First off be careful! don't stab your self with the screw driver or cut your self on the metal 9 volt case because it is sharp as a razor!
First pry up one side of the 9 volt as shown.
Then start to pry around the edge until it is wide enough to pull the inside out. As shown.
Step 5: Assembly Step One: Led Set Up
First place all three led's on there side lined up next to each other on the black 9 volt battery bottom and use the push pin to make small holes at the end of on the metal leads in the black 9 volt battery bottom you should have 6 holes. Note: Push just enough to get the tip of the push pin through, if you push it all the way through the hole will be to big.
Now line up the LED's from minus to plus all in a row then push them through the black 9 volt bottom as shown. (see the picture on how to tell plus from minus on an LED.)
Step 6: Assembly Step Two: Soldering Leds
First cut the copper wire to and lay it between pin +2 and pin -3 and solder the wire and pin 2 & 3 together as shown.
Now cut the copper wire to and lay it between pin +4 and pin -5 and solder the wire and pin 4 & 5 together as shown
Now the LEDs are in place go to step three.
Step 7: Assembly Step Three: Power Leads
Now that you have the LED's soldered in place now solder on the power leads on and use your wacky tack to hold the leads in place as shown. Don't forget to check what side is positive and what side is negative check the picture on step two to figure this out if you don't know.
Once you have the positive and negative leads soldered on then rap them around like the picture as shown.
Now test it to see if you did step two right touch the red to the + or positive and the black to the - or negative if it lights up you did it right! if not go back to step two and review.
Step 8: Assembly Step 4: Power Connector
The next step is to attach the the power connectors and solder them in place.
Remember the plus and minus are reversed from the battery
Step 9: Assembly Step Five: Hot Glue!
Now that you have the wires squished between the two sides make sure the wires are with in the foot print of ether side.
Now lay it on it side and squirt hot glue in the middle just enough that it comes to the sides and let it cool and get hard enough not to move.
Next turn it over and squirt glue in the middle on the other side and just enough that it comes to the sides and let it cool and get hard.
Once you have it mostly full, now take it and turn it on each and finish fill each side until full.
Pro tip: find some metal and as you fill the last bit press it on the metal and it will press it smooth and cool it quickly at the same time. It will give it a smoother better finished look.
Step 10: How to Use Your New Light
So now that you have it done you can stick a magnet to the side of the 9 volt and mount it any where. If you hook the light on to one side of the battery and turn it on the connector until it makes contact with the other side you can use it like an on and off switch. I like to keep a few of them mounted under my bed to the bed frame In case of an emergency at night this way I always know where my flash light is.