This is my first Instructable so, please bear with me.
Often when I'm working, I could really use a small but powerful torch and a mobile phone charger. As I always have my DeWalt drill with me, I thought I should make one that will accept my 18V Li-Ion battery.
So here is a step by step guide of how I made a combined torch and USB charger for around £10.
Any constructive criticism, greatly received.
Step 1: The Enclosure
I chose a plain black project box from Maplin for the enclosure.
The dimensions of the box are: L 100mm x W 76mm x D 40mm.
Any sort of box will do as long as there is sufficient room inside.
The front of the box will need cutting out to accept the clip in part of the battery.
The way I do this, is by drilling the box and then filing the slots to the correct shape. This is probably much easier with a Dremmel tool but, this is the way I have always done it.
The cut-out needed is in picture 3.
Pencil is very difficult to see on the glossy black box so I always do the setting out on masking tape.
The cut-out on the base of the box is 33mm deep.
When the cutting is done, it should look like picture 5.
Step 2: Battery Connections
For the battery terminals, I used some long crimp terminals I had. Anything similar could be used or even just pieces of steel with wire soldered on.
I used a piece of thin MDF to secure the terminals in place. When everything was correctly lined up, I hot glued the MDF and terminals into place.
Once cooled, this is very solid and the battery clips on smoothly. The terminals engage nicely with the female terminals on the battery.
Step 3: The Curcuit
I am using a DC - DC converter for the USB charger.
The converter I am using is this one: eBay: DC - DC Converter
Any similar device would do the job but, I can vouch for how well this one performs.
It takes the 18v from the battery and converts it to 5.1v at up to 3A.
For the torch, I am using 15 LEDs in a 5 x 3 array.
I used the following website to find the correct wiring and current limiting resistors for the LEDs: LED Calculator
I used 85Ω resistors as I already had them and they were close enough to the figure quoted by the calculator.
A switch will be used to swap between the two circuits.
Step 4: More Box Cutting
We now need to cut further holes for the USB socket and the LEDs.
The LED holes were just set out on a grid and then drilled.
The LEDs are 5mm and I find that a 4.5mm hole provides a nice tight fit so no glue is required to hold them in.
The LEDs were pushed into the holes and then soldered along with the resistors, as in the wiring diagram.
The USB socket of the converter was drilled and filed as with the earlier battery slot.
Step 5: Nearly There
Now just wire everything together following the wiring diagram.
You can use block connectors, solder and heat shrink or crimp terminals for the wiring.
Then just screw the lid on and its finished.
It will happily charge an iPhone or iPad and the torch is bright enough for most jobs.