After seeing information on Joule Thief LED drivers on the internet I decided to try making them. After getting some working units I started experimenting ( as I usually do ) with different sources of parts from objects I can recycle.
I found that the Kodak Max disposable camera had a transistor that worked in this circuit and a 1k resistor also required. So the idea was born to try and modify the circuit in such a way I can get my daughter involved ( and hopefully interested in electronics and recycling and away from Nintendo DS and TV )...
Her response to the finished torch.... " This is sooooo cool "...
Then I saw the Get the LED out comp and decided to share. So here is my first attempt at an Instructable.. I hope someone finds it interesting or even maybe useful.
Step 1: Get Your Bits..
Ok so now you know I am an electronics packrat, so here is what you will need if you wish to give it a try.
A Kodak disposable camera is required, mine was free from a photo lab that usually throws them away.
A switch that I rescued from a broken phone.
Some enamelled wire also rescued but from a microwave oven. If you are not exeprienced with high voltage then I do not reccomend you pulling apart a microwave as there is a high voltage capacitor in microwaves that can possibly kill you. The wire I used was from the microwave fan motor, you can source wire from most electronics shops or salvage from many other places like dead motors etc.
The last thing needed was a white LED, the more light output it has the better. This was the only thing I bought so this project only cost a little in money but more in time.
Oh absolute last thing that is required is lots of paper under the project with all my scribblings on it. Without this the project will never work. hehehe..
Feel free to reproduce your own paper with scribblings on it to get better results.
Step 2: Disassemble Kodak.
Now comes the fun part...
Remove the battery from the bottom of the camera and leave it somewhere safe for about a month. This is to allow the capacitor to discharge.
The capacitor in these cameras hold a charge of around 300 volts, and can give you a nasty shock/burn if handled incorrectly, if you are very unlucky it could even kill someone. There are many sites on the internet regarding the dangers of these cameras and the safe methods of salvaging parts from within them. Please search and take heed of any warnings.
If you know what you are doing then forget about waiting a month and dive right in like I do.
Remove the back cover using the tabs at each end of the camera and prying carefully, then remove the front cover but be vary careful where you put your fingers, remember there is 300 volts in there so don't touch any circuit board.
This should leave the center section with circuit board as shown in first photo.
Remove the lens assembly via 2 screws then carefully remove the circuit board. It shoud come away from the plastic housing quite easily. The circuit is shown in the next photo, the capacitor with the big bite is shown on the right hand side. Get something metallic with a plastic handle that you don't mind damaging ( like an old screwdriver that needs replacing ) and touch it across the capacitors leads. If there is any charge in the capacitor then you will get sparks and maybe a bang. You could lose a bit of your screwdriver at this point. Better the screwdriver than your finger.
Cut off the capacitor without damaging the circuit board. As shown in the third photo, the circuit is now safe to do with as you wish.
Step 3: Prepare the Circuit, Ie: Rip It to Bits..
Here you can go silly removing bits, everything can be removed except the transistor, the battery terminals and the 1k resistor ( R1 ) as shown.
I rewind the transformer to suit the circuit.
Start by removing the "tape" wrapped around the transformer as shown in the second photo.
Carefully remove the two E shaped formers, they are very brittle and I like to replace them once the coil has been rewound so great care is required here.
Once removed as shown in the third photo, unwind the "tape" covering the wire. Cut the ends of the wire close to the transformer legs and unwind the wire.
You will finally get to some very fine wire that has multiple hundreds of turns around the plastic former. I find it easier to place a small jewelers screwdriver through the plastic former here and slowly pull on the end of the wire and let the former spin around the screwdriver. As shown in next photo.
There is a lot of wire here.
You may wish to use this wire to rewind the transformer but I have not tried it so not sure how it would go, may be a little too fine and you risk breaking the wire while winding.
So you will end up with a empty plastic former and a mess of wire and bits as shown in the next photo, keep all the bits except for the wire. ( unless you wish to try reusing the wire ).
Step 4: The Scarey Bit..
Rewinding the coil.. Not as hard as it looks...
My daughter Rachel managed to do it and I can as well so anyone can wind a coil. One point here is if you have small fingers or are very good with them you have a distinct advantage. If you are having trouble winding the coils then get a 10 year old child to help. hehehe..
Take a one meter length of fine enamelled wire and fold it in half.
Mark the ends as shown in the drawing of the first photo. A1 and B1 should be at the fold, A2 and B2 should be on the loose ends. A1 and A@ have to be on one side and B1 and B2 on the other. If you mix these up then the project will not work.
If you look at the third photo you will see that A1 and B1 is on the right hand side of the transformer when looking at it from the bottom. Leaving about 25mm to 30mm of wire over, start winding the coil, you should be winding two wires A and B at the same time, wind neatly and count 23 to 25 full turns around the former.
The two loose ends, A2 and B2 should finish the opposite side to where you started winding as shown in the second photo, sorry if it is hard to see.
I like to add a little super glue to the coils now to help keep them in place. If you do too then let it dry before doing anything else as it is very easy to end up with a little growth on your finger that looks like a transformer.
When ready wrap the wires around the transformer legs two or three times as close to the plastic as possible as shown on the paper in photo 3.
I di not worry about scraping the enamel off the wire at this point as I have found soldering the wire burns off the enamel enough to form a good connection.
Heat the pins and wire and when hot touch with a little solder to get a good joint, keep as close to the plastic former as possible as you will need enough length on the legs to remount on the circuit board. When soldered test with a multimeter ( or battery and globe/led ) to make sure you have a good connection to the correct legs.
When you are happy clip off the excess wire as shown in photo 4.
Congratulations you now have a new transformer. That was not so hard now was it. Once you have done a few they will seem very easy.
Step 5: Putting It All Together.
Ok now that we have wound our first coil congratulations, not as hard as it looked was it.?
Now I like to put the transformer back together like it was when I first removed it.
Take the thick tape and wind it around the wire to cover it, this will help protct the coil while handling etc. Then replace the E formers as shown in the first photo. Once they are both replaced, wind the thin tape around the E formers and thats it, now looks like it originally did but will now work for us.
Place the transformer back in its origional position and resolder it in place.
Looking at the second photo place and solder a wire link from point 1 to point 2 ( I usually put this on the top of the board ) and another wire link from point 3 to point 4 as shown.
If you want to put a switch in to turn on and off then cut the track where shown using a sharp tool or a very small screw driver.
Now solder in the LED at point 5 and point 6. the long lead on the LED goes to point 5 and the short lead of the LED goes to point 6 which is the - side of the battery.
To wire in a switch solder the middle pin of the switch to the + side of the battery treminal as shown on the circuit board, this is the orange wire shown going to the switch in the third photo.
Solder a wire to another one of the switch pins and then solder the other end of this wire to a point just past where you cut the track. This is the white wire goes in the third photo.
The third photo shows the link ( red wire ) and switch and LED connections on the top of the circuit.
The wire I used came from the flash connections from this camera.
Step 6: Testing Testing 1.. 2.. Smoke....
Now we have finished making the circuit and ready to test it before mounting it back in the camera shell.
Check all your connections a few times before adding a battery. Make sure there is no wire, solder or anything else under ther circuit BEFORE attaching the battery.
Once you are happy you are not going to short anything out and you have the circuit correct, add the battery, make sure you have it the correct way around, the positive side of the battery goes to the terminal that is short and directly on the circuit, the negative end is on the long terminal which extends away from the circuit board. ( it is also marked on the circuit board )
If you connect the battery and you get light as shown in the second photo GREAT work. All you have to do now is mount it.
If you didn't get any light then remove the battery, check everything then try again with the switch in the other position ( if you cut the track and wired in the switch )
Step 7: Lets Mount This Thing..
We need to mount this thing in the center section of the camera.
If you put a switch on, cut a hole in the plastic center and the back as shown in the second photo, you can mount the switch elsewhere, just cut holes as needed.
The hole I cut in the back section is too big but I was in a hurry to get this Instructable finished. Looks rough but works.
I used hot glue to mount the switch as shown in the third photo.
Step 8: Let There Be Light.
To allow the mounting of the LED behind the lens of the camera, we need to enlarge the hole behind the camera lens shown in the first photo.
Rotate the lens cover and the cover will pull away which will let you remove the lens as shown in second photo.
Enlarge the hole with a sharp knife or drill bit etc until it is big enough for the LED to sit in as shown in photo three.
You will now need to remove some plastic from the plastic piece we are mounting this on as shown in photo four.
Step 9: More Mounting Required.
Now mount the lens assembly and the lens assembly support piece.
This may be a little difficult due to our mods but just adjust everything till it fits. Don't be afraid to remove more plastic as needed. Screw down with the two small screws from their origional positions as shown in first photo.
Push the LED from the back so it is positioned behind the lens, photo two, you may want to use some hot glue here to make sure it doesn't move.
Push the front cover back onto the camera and then the back cover, photo three and four.
Now the battery can be put in, make sure the battery is the correct way around, look at circuit board for markings of polarity. Photo five.
Step 10: Let There Be Light 2.
Turn on your switch ( if you installed one and it was off )..
Now bask in the glow of your glory....
It is interesting as a torch or night light or else use your imagination for other things..
I stuffed up..
Now if like me you were rushing you will need to pull the covers off again, go to next step and find out why.
Step 11: Fixin My Ooops.
Well if you didn't notice the ooops, and you followed my instructions exactly you may have noticed a big hole where the Flash used to be..
Remove covers and replace flash, it doesn't need anything connected its just there to fill the hole, refer first photo.
Now once I have it all back together here it is in all its glory..
In the second photo you will see my first attempt at top of photo where I mounted the LED inside the flash enclosure.
I removed the flash tube very carefully and then dug a big hole to push the LED through, I also put heat shrink on the leads of the LED to prevent shorts. This method is more difficult so I would definately suggest putting the LED behind the camera lens.
Well thats about it. I hope you have as much fun if you try this as my daughter I did.
I hope my first instructable is not too bad.