Fantastic Solar Keychain Flashlight.

Introduction: Fantastic Solar Keychain Flashlight.

About: I am an electrical repair tech by day and an engineer by night, after work or free time.

Almost everyone who has ever tried to unlock a door in the dark knows the struggle and frustration of trying to connect both the key and the key hole. It seems almost impossible to get into your car/home/work at night without any light. Now when I get home from school and work its usually around 10pm for both, as I work overnights and take night classes. Because of the pitch black hole I walk into before my door I was in need of a small flashlight. 

I saw a few kechain flashlights at the store and the prices were unreasonable. The cheapest one I found was for 5 dollars, now that may not seem like a lot of money but when you break the product down to its basics and purpose you will quickly see how overpriced it is. Think about it for a minute. On the inside of the flashlight there will be one white led, maybe a resistor, a tact switch and a coincell battery. Aside from the battery everything else is cheap to buy online in bulk. The battery is another reason why I was pushed to not buy it. Simply because once they die, you have to buy more. Batteries, as we all know aren't cheap. For the good ones that is. A button cell could drive an led for quite sometime, I'm sure. But I like the idea of being able to recharge the battery. (solar) and not having to replace it. 

I made all of this for under 3 dollars. and it can be used over and over again. I picked up a few cheap solar yard lights from the dollar store and  used them to make it into a flashlight. The solar light was only one dollar and it included everything we need to build this. Aside from what was in the light I had to use a few other things I was able to collect off of scrap. 

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Step 1: All Things Needed. (no Picture)

You will need 
one solar yard light with a build in battery.
an altoid smalls tin
key chain ring
soldering iron
de soldering iron
dremel with highspeed saw bit
hot glue
an additional led ( if you want it. one is bright enough but two is better)

The battery that was built into the solar light I picked up was small but to my surprise worked very well. It was rated at 1.2volts at 40mah. It takes about an hour or two in the sunlight to charge enough to drive the led for a very decent amount of time. 

Step 2: The Break Down.

The only thing I did was I switched out the iductor for a diffenrent value to create a brighter output. 

First take apart the light and disconnect everything. 
If you are swapping out the inductor for a different vlaue, do so now. If you happen to find the exact solar light I used then look up the inductor value via the color code on it. 

Why did we disconnect everything? Well when we put it into the altoids tin it will be easier to do so with less parts dangling around the circuit board. 

Step 3: To the Tin! Part 1

Now lets prepare the tin. 
1st- outline the solar panel on the lid of the tin to get an accurate cut mark. then use a dremel to cut the outlined.
2nd- hotglue the solarpanel from the otherside of the tins lid. 

Step 4: The Tin. Part 2

Now lets prepare the tin. We will be cutting a hole for the led(s) and switch. We will also be cutting two small holes on the back of the tin for the key ring.

Step 5: Making the Circuit a Little Better. for Fit.

I suggested to disconnect everything from the circuit earlier. Doing so will help mount everything nicely in the tin. I would also suggest desoldering the switch and extending it with wires to fit nicely in the new hole. 
Be sure to insulate where needed to prevent a short

Step 6: The Tin. Part 3.

Now we will mount everything inside the tin! before we mount anything in the tin be sure to insulate the bottom of the tin with electrical tape to prevent the circuit board from shorting. 
After all you componets are re-connected to the circuit board and the tin is well insulated;
1st- hot glue the circuit board inside the tin while maintaining enough room for everything else
2nd- hotglue the battery in place
3rd- hot glue the switch
4th- hot glue the led or leds in the precut holes. make them as straight as possible before the glue sets to ensure a nice even light output.
5th- place the tins lid pack on the hinges and re-attach the solar panel. After it is soldered be sure to insulate. 
6th- Place a little bit of hot glue arounf the tins lid and close it up. The glue keeps it shut for good. Not permanetly.
7th- add the key ring 

Step 7: Done! Test It Out and Add It to Your Keys!

You are now finished! You no longer have to worry about not being able to see your keys positioning at night! Also this is a cheap alternative to other key chain flashlights. It costs less and it it rechargeable so you never have to worry about buying batteries! Thanks for viewing and I hope you enjoyed this! 

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