What to do when you have a load of old nokia phones (many people do) and a busted LED torch? Make a Frankenstein's Monster of a bicycle light of course!

I kind of get a bit forgetfull about getting new batteries or taking out and charging the ones for my bicycle lights.

Police hassle me for not having lights and cars beep at me. I don't really need lights myself. If you can see me to beep at me, then there isn't a problem!! I cylcle in the city mostly and millions of wasted lumens from street lights show me where to go (and pollute the night sky above us all). So actually, i have these bike lights for eveyone else's convinience. Never mind.

Wouldn't a bike light that didn't need a specific adapter to recharge be nice? You could plug it in anywhere if you got stuck and your battery was low. It seems in every office, home or college there is a little black ac adapter lurking around with nokia written on it.

So a plan was formed. Merge a torch and old phone into a compact, powerful and convinient (and probably awesome) bicylce light.

Read on and ignore the spelling mistakes........

Step 1: The Materials

I had a broken hand cranked LED torch gotten from ebay for cheap (i actaully didn't order it because it was broken, it got damaged on the way), and a load of old nokia phones from several years back. Surely there must be a way to merge these technologies, i thought.

The LED matrix from the torch and it's reflector case was nice. Unfortunately the body of the torch and hand crank bit was very brittle and had broken too badly to repair it.

Then there was the phone. The screen was a bit dodgy, but the 3.7v battery was in good order and the phone still charged up, so some of the circuit board still functioned.

Step 2: Chop It Up!!

Well i wanted the light to be roughly the size of the phone when finished, so i decided to chop the top off the phone!

I guessed that the charging part of the circuit would be in the lower part of the circuit board, near where the wall charger goes in, so it would not be affected. Also i wanted to retain the function of the LCD screen so i could see when the phone/light is charging.

The plan was to.....

1. Dismantle the phone.

2. Cut the top off the circuit board just above the screen contacts.

3. Cut the outer case and LCD screen layer to match the new lenght of the circuit board.

So i got out me hacksaw.......

And it turned out i was right. The phone still charged the battery and the screen still displays the battey charging animation, despite having the top 2cm lopped off! Excellent.

(Be a bit careful cutting the circuit board, don't bash any components loose on the charging end of the board. And be VERY careful cutting the layer with the LCD screen, its a bit flimsy on these type of phones. I used the "heated blade" method and melted the plastic.)

Step 3: On/Off and Mounting

I needed to hook up an ON/OFF switch between the battery and my LED matrix. I had a few old switches knockin' around, and found one to suit my purpose.

I also would need a way to mount the finished light on my bike. I took the mounting parts off a spare rear bike light. One part for the handle bars and one to attached to the new light somehow!

So i took a look at the back cover of the phone and decided on where to make the holes for the mount and the switch.

I removed the old SIM card pins to make room for a bolt to attach the bike mount, and marked the area with a pen.

I roughly fitted in the light switch and marked some places for drilling for the switch lever and the screw holes.

Step 4: Drilling

So, holes marked in the rear case, off i went to drill em.

I used a drill bit roughly the size of the switch lever, drilled the hole, then filed out the rest to match the full action of the switch, ON to OFF, about 5 or 6mm.

Then 2 small holes for the screws to hold the switch in place.

I got a 4mm nut and bolt to hold the mount in place. I drilled out a 4mm hole on the pre marked spot. I ao drill a hole in the mount part that would be attached to the light, so i could put the bolt through and tighten to the nut.

So all holes drilled and correct, i fitted the switch with a bit of super glue and put 2 small screws in. The same with the mount, glue into place and nut+bolt attached.

Step 5: Some Electrics

So the mount and the switch were now in place, glue all dry. Onto the soldering i went.

Seeing as the battery was nicely marked with a positive and negative symbol, it was easy to find where to run the wires from the LED matrix to.

The one issue was to figure out which of the 2 sets of terminals on the battery was for input, ie from the charging circuit, and which set was the power out, ie power to the phone.

This was done with the trusty multimeter set to voltage. And it turned out that one set of + and - terminals gave off no voltage, while the other set gave out the voltage of the battery. So i knew which set to hook up to my LED matrix and switch.

I threaded the wires from my switch and my LED matrix through the case and soldered them onto their corresponding battery terminals. The battery still fitted in as normal.

It was time for a test.

Step 6: The Big Test...

So did it work?

'Course it did. Despite having a chunk chopped off its top, when reassembled with new switch, mount and LEDs in place, the phone still had charging funtionality.

To be honest, i was kind of relieved! I've had bad things go wrong with my creations before (i recall the SCSI card/tin foil fire incident, among others...).

So when plugged into a standard nokia charger the phone lights up and the charge animation comes on. Cool. Is it actaully charging? I'm going to say yes.

Disconnected from the charger, i then hit the switch to turn it on. I was nearly blinded by the sheer amazingness and brightness of it. It took me several moments to recover.......

Step 7: Still to Do...

There are several things i still have to do to finish this light.

1. Glue LCD screen down onto circuit board to make charge animation display less wonky.

2. Glue and seal LED matrix and housing onto phone.

3. Seal where the keypad used to be, probably using silicone bath sealant in a messy way.

4. Test the light out on the road and see how many hours of life i can get off one charge, and if it is
weather proof.

So thats the end of the instuctable. I hope its useful. Its my first one, by the way. A bit overdue i think, considering all the years and silly amounts of hackery and gadget building that goes on in my room!!

See ya.

Step 8: Slight Update

I finished off the light next day.

I glued it all together and fixed amount to my handle bars to attach the light to.

Also i gave it an hour or 2 charging off a nokia charger and then i disconnected it and i left it on over night. It was still going strong next morning. good news, eh?