Instructables

Hack-A-Lantern: Recycled Computer Power Supply Flashlight

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Picture of Hack-A-Lantern: Recycled Computer Power Supply Flashlight
Do you have lots of spare computer parts? Do you like to be prepared for emergencies? Are you ready for the zombie apocalypse? Do you get what I mean when I say the word "Junk-Punk"?

If so, then you should build yourself a Recycled Computer Power Supply Lantern!
Using salvaged, repurposed, and reused components, we'll build a 12V/11w electric lantern.

This all started recently when I was talking with a friend at the Milwaukee Makerspace. I was working on a simple wiring project and chatting and the friend showed me a couple of 5ah lead acid batteries he salvaged, which were perfectly good, and he was giving to anybody who wanted one. It's a great size rechargeable battery, and the size and shape reminded me of the "old-fashioned" lanterns that use a 9V dry cell. That, plus a discussion of zombie movies made me wonder - Do I have the skills to not only build a portable light from little more than scrap materials, but also build something better than I could buy?

I took it as a challenge, and proceeded to build the Power Supply Lantern. 
 
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Step 1: Tools & Materials

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To start, let's review the tools and materials for the project.

Nearly all materials for this project were recycled, salvaged, or reused. The project was based on the materials that I had on hand. If you want to build something similar, you might have to buy something. Better yet, why don't you build a project using just the materials YOU have on hand, and see what you come up with!

Materials:
Dead computer power supply
12V landscape lighting bulb
12V rechargeable battery - 5AH or other size that fits inside power supply
Foam or other scrap spacing material
Glue
1/4" crimp-on spade terminals
Zip-Ties
Electric tape or heat-shrink
Battery Charger


You might notice that I didn't list either a switch or any wire in the list of materials. That's because we will re-use the switch, wiring, and power port already in the power supply.

Tools are basic, that no respectable DIY'er would be without, but when it comes down to it, most could all be replaced with a Swiss Army Knife or Leatherman.

Tools:
Phillips Screw Driver
Wire Stripper
Wire Crimper
Side Cutters
Drill and bits
Multimeter (Optional)

Step 2: Open & Remove the Un-Needed

First thing is to open up the power supply.

Remove the four phillips screws that hold the cover on the power supply, and then remove the cover. The cover is actually 3 sides, or half the power supply. Seperate the two parts.

Inside, you will see lots of wire, a circuit board, a fan, and the switch and power port.

Remove the four screws holding in the cooling fan. Unplug the fan from the circuit board, and then set it to the side as material for one of your future projects.

Remove the screws holding down the circuit board. Then locate the wires from the switch and power connector, and follow them to where they connect on the board. Snip the wires close to the board to maximize the length of the cut wire, still attached to the switch and power connector.

Remove the circuit board and set to the side.

You now have a mostly empty box with just a couple of wires on the switch and power supply. We'll reuse those as part of the project. You should have enough wire to reach the battery and the light bulb.

Step 3: Battery

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The battery used for the project is a 5 amp-hour sealed lead-acid battery. It fits nicely inside the power supply case.

The terminals on the battery are 1/4" male spade connectors. These are easy to work with, by crimping spade connectors onto wires and then just pushing them onto the battery connector terminals.

The battery is marked with the Positive in Red and the Negative in black, and has a plastic protector around the Positive Terminal to help reduce accidental short-circuits.

Put the battery into one half of the power supply case to ensure that it fits. You may want to use a pencil or marker to outline it so you know where the battery lines up without it being in the case.

Step 4: Lamp

The lamp is a 12-volt, 11-watt light bulb left-over from another project. It would typically be used in outdoor, low-voltage landscape lighting, powered by a 12V AC transformer.

Something as simple as a light bulb doesn't really care if it's powered by AC or DC power, as long as the voltage is right. We are using a 12V battery, so there's no problem repurposing this bulb.

The lamp will take the place of the fan. Hold up the bulb to circular grate where the fan was. Mark how much space the bulb will take up. It's round, and so is the fan, so it should fit OK, but not all the way back into the case. (A different size bulb might fit flush, or even INSIDE the case!)

Using the side-cutters or a tin-snips, snip the tin fan grating to make the bulb fit. You could also use a Dremel or other cutting tool.

Test-fit the bulb, but don't permanently attach it yet. First, we will want to wire up the lantern.

Step 5: Wiring it Up

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Wiring on a flashlight is pretty basic. A complete circuit is just Battery Positive to Switch to Bulb and back to Battery Negative.

Since this is a rechargeable battery, it would be nice to also add a way to recharge the lantern without taking it apart to access the battery. To do that, we'll reuse the power cord port as a place to connect the charger to.

First, check to make sure the wires on the switch and power inlet will reach the battery and the bulb.

The "115/230" power switch won't be used, so its red wires can be snipped-off. Save them for reuse. It's good heavy wire, and red is typically used to indicate Positive polarity.

Strip and twist together one wire from each of the power switch and the power inlet. Add a female spade terminal and crimp it on. This connector goes to the Positive terminal of the battery. The other wire of the switch goes to the  bulb. 

The OTHER wire of the power inlet goes to the opposite side of the bulb. That side of the bulb also goes to the battery negative. This bulb has "multi-terminals" on it, so it's easy to connect two wires at once to a terminal - one with a spade connector, and one with a bare wire tightened down under a screw.

Once you are done, power will only go to the bulb when the switch is on, but power will always be connected to two of the pins of the power inlet. (Cut off the third wire.) That way a battery charger can be connected to the two pins to recharge the battery. Mark the two pins with the correct polarity.


(A note on reusing the switch: Switches and other components often have 2 sets of ratings - one for AC and one for DC. The ratings are typically much LOWER for DC. Use a flashlight to look closely on the side of the switch, and you will see its power rating. Because this is only a 1 Amp project, this switch will work fine.)


Step 6: Handle

One classic element of a lantern is a distinct handle, separate from the body of the light.
(Unlike a flashlight, where you simply grasp around the entire shape of the flashlight.)

Usually, I would use some bolts and spacers, and a cross-piece of wood or metal to build a handle. However, I didn't have any material handy that seemed to suit it - other than the wires still connected to the circuit board, set aside earlier.

Those wires were bundled tightly together, and the diameter was about right to be comfortable in the hand. I cut the bundle of wires close to the surface of the board.

I measured the diameter of the wire bundle by feeding it through a drill index. If seemed to fit best in the 1/2" hole. That meant than I could drill 1/2" holes through the sheet metal, and then feed the wires right through. I drilled two holes, centered side-to-side. There were already two stamp marks in the metal about 3/4" from either end, so I used those as a reference for how far in from the ends to drill.

With the holes drilled, I fed the cut end of the wires through from the inside of the case, up and over the top, and back through the other hole. The original computer power board connector is too large to fit through the hole, so it acts as a stop. 

On the other end. I wrapped two zip-ties around the wire to bind them in place. Then I folded back the extra wire, zip-tied it again, and cut off the excess wires.

Step 7: Assembly

With the wiring finished and the handle done, the whole thing just has to be assembled back together.

Now is the time to glue in place the lamp and the battery.

I glued the lamp in place with silicon glue. It works well over a range of temperatures. The lamp will get warm with use, so hot-glue would be a poor choice.

On the other hand, a hot-glue gun worked great to glue the battery into the case. I also glued two bits of scrap foam to act as spacers between the battery and the cover.

Once the glue is cool/dry, reassemble the cover onto the case (minding the foam padding and wire handle) and put the four cover screws back in.

To recharge, I just hook up the small battery charger I already had to the two charging pins, which I noted the polarity of.

Step 8: Test it out!

Once the lantern is together - go test it out!

It's great for camping, blackouts, Trick-or-Treating - heck, you might even throw the whole thing inside a Jack-0-Lantern.

With the nice square base, it sits very well, so it can be set down and allow both hands free to do what you need to do. You can also sit the lantern on end to point the light straight up and bounce-light an entire room.

I like the way the handle feels. It's surprisingly comfortable, and the lantern hangs just right from it.

It's a 5AH battery, and the bulb is basically 1 amp, so that means it's a 4-hour run time to 80% battery discharge.

The lamp itself is rather bright and has a large area of illumination - it's most comparable to a car headlight in it's pattern, although not as bright as that.

Now you go make one!
Will yours be more steam-punkier? Will you use a different bulb? Let me know how yours turns out!

Check out more fun DIY recycling projects on http://ecoprojecteer.net/
elic2 years ago
You left the 220/115v plug and used it to charge the battery. It is a safety problem - someone can plug through it the battery to the 220/115 volt and blow the battery! Please destroy the plug or make it unusual.
Liam.great98 elic11 months ago

Things like that are fine when it’s only the creator using it. If it was going to be mass produced and sold, obviously you’d want to change that.

eyesee2 years ago
good
poofrabbit2 years ago
Hey congratulations on being a finalist in the hack it contest! Good luck to you!
keebler14332 years ago
As a precaution, you should be careful when taking apart comp. power supplies! They still have power in them. A guy in my area (KC) was electrocuted from taking apart his power supply. Just a heads up!
Dont touch the Capacitors and you usually get away with it fine :)
sdfgeoff2 years ago
With a big(ish) battery like that, surely you could put a car headlight lamp in. I'm sure that would be bright enough for any possible need.
bennelson (author)  sdfgeoff2 years ago
Sealed-beam car headlamps are commonly 55 watts. The landscape light is 11 watts.
The battery could run a car lamp for 1 hour or the lamp I used for 5 hours. It's more than bright enough for my needs, but yes, a person could use a headlight if they wanted to.
Appropriate idea :) cool .. you saved amount of casing .. and 1suggestion- Plz find out option of charging .. put charging adapter inside the lamp and connect that with the female shocket(which is already along with the case) then you'll need only power cable to plug in and charge .. it's easy and SAFE .. (in your recent design..if by mistake beginners attached power cable like computer .. your battery will blast :( .. )
MoritzB2 years ago
It would be better if you had installed the charger inside the flashlight.
But nevertheless good project.
Great ible ! I love recycle projects like this, there are so many items out there for re-use. This whole project couldbe done using all recycled parts. It is genious in its simplicity. Two thumbs way up!
imperio2 years ago
no one can say that it is not a bright idea!
jim_lewis12 years ago
I have to echo the concern regarding reusing the power inlet.
Connecting what is clearly a mains power input to the battery terminals is VERY DUMB.
Someone, (perhaps even you in a while when you forget how it's wired), will connect this to the mains and the results will be ugly.
Good design is first and foremost inherently safe. This is an accident waiting to happen.
ralenti2 years ago
Why not LED? Much more bang for your battery!
Good idea!
One suggestion:
It has enough space to put the charger in the box!
The charger also does not weigh that much!
Then, to load only necessary to use a standard PC cable.
woofman2 years ago
I must have 5 leftover power supplies lying around waiting for projects just like this. What a great idea!
mickeypop2 years ago
you have enough room to add a small 12v transformer and a few diodes and you could plug it in to recharge the battery.
j1shalack2 years ago
I love the idea. Any computer geek will instantly recognize it. My only suggestion is to twist the "handle" wires so they will be more like a rope...?
Gabse2 years ago
Isn't it very Dangerous whir the normal Power Plug?
-A-N-D-Y- Gabse2 years ago
Unfortunately instructables is not policed for safety issues, there are some really dumb reuses of mains fittings on here. I should create an instructable of a cut off mains cord to use as a child's toy :p. I'm not the intructables safety police either but when I see things like this I cringe most likely as you did! :) At least one of the terminals used was the earth and hopefully the other was neutral (assuming the plug/socket etc is wired correctly) so inserting a mains cable will either rapidly blow a fuse/trip somewhere or short the battery across the house wiring? I wouldn't want to be the one to find out ;)
kp912 years ago
whenever I need a charger, switching power supply, or the like, I can usually find one at my local Habitat for Humanity store for next to nothing. Everything from 3v to 24v has been there at least once.

good value for you and for the community
chase326152 years ago
I like the steampunk hint to it i think you should go all out and steampunk the whole thing
bennelson (author)  chase326152 years ago
Items that I make from recycled, salvaged, and junk materials tend to have a certain look about them.
I actually have a term for this; it's "Junk-Punk".
Please feel free to use this term and share it with all your friends.
ok thats really cool, alot of my friends are on instructables and ill tell them to follow you. i like your stuff its awesome
bennelson (author)  chase326152 years ago
Thanks Chase!
nsnip2 years ago
This is all kinds of awesome! Did you consider mounting the battery charger inside of the case and using the power supply's cable to charge?
bennelson (author)  nsnip2 years ago
I didn't, just because I already had a "wall-wort"-style charger that is already exactly the right charger for this battery. However, I really LIKE the idea of having an integrated charger, just because it would be so cool just to run the power cord right from the wall into the power supply.

Sometimes a lower light level, is all you need to be able to navigate around a room.
You could use the 115/230 switch to put a resistor, into the circuit, so you  could have a hi/lo setup. 
techno guy2 years ago
that looks pretty cool
agis682 years ago
very creative.
bhvm2 years ago
Nice one. Very cool looking.
I wish your future version uses power LEDs.
barbnelson2 years ago
Looks great! But is it heavy?
bennelson (author)  barbnelson2 years ago
I'd say it's "Hefty".

It's not particularly light, but hangs very nicely from the handle. It has a sense of solidness to it.
bennelson (author)  bennelson2 years ago
Good for bashing zombies....
Schmidty162 years ago
very cool voted for
hertzgamma2 years ago
Great idea!
LEDs would not work better?
bennelson (author)  benderbrasil2 years ago
LEDs are wonderful things, but don't confuse efficiency for practicality or light output.

I already had a 12V bulb just kicking around, and it lights up a large area.

To purchase an LED/LEDs with the same light output, it would have been significantly more expensive, more time spent soldering, etc. etc.

If you already have some high-output LEDs laying about unused, they would be GREAT to use in a similar project.
A possible improvement to his project would be to assemble a rectifier and regulator so it can be charged directly from the wall using an IEC cord.
iPodGuy2 years ago
This is really cool!