Headlight Hack! Add a Brightness Control and LED to an Old Headlamp

Do you have an old headlamp? Do you want a high-brightness LED headlamp? Do you have limited electronics knowledge? Well I present to you the LED headlamp hack! I had an old head lamp that was begging to be hacked, it was old and didn't work. So I took my trusty drill, wire strippers, and soldering iron and made it into this ever-so-amazing LED headlamp. This is how I did it and how you can do it too.

Step 1: Tools and Materials

You will need,

Tools:
Soldering gun
wire strippers (optional but very helpful)
tin snips (again, optional but very helpful)
helping hands (helpful and again optional)
drill / drill bits 
knife

Stuff:
Old headlamp
wire
solder
led (preferably high brightness.)
resistor (see step 2 for choosing the right one)
10k POT
9V Battery
9V Battery holder
toggle switch or push on push off switch
circuit board (optional but helpful)

Step 2: Choosing Your Things

Your headlamp really only depends on what you want to work with
1) do you want a a lot of room to do a lot of awesome stuff?
2) do you want high quality plastic that wont crack when you drill it?
3) do you want a large battery pack that can hold all your dream headlight electronic components components?
4) do you want a headlamp that seams like it was built for taking apart and making more awesome?
5) do you want a large reflector that leaves a big hole of light write where you want it most?

I was able to get all of these in my headlamp (even the big hole in the light) so I consider my self pretty lucky. Although my headlamp is not a running, backpacking, ultra high tech lamp with multiple settings and dimming at the push of a button. It was more of a spelunking/construction headlamp with two settings on and off. not to mention it was old, and therefor, simple. Easy to take apart and gut.

Now along the lines of choosing an LED.
1) what shape of LED do you want 
2) what color of LED do you want (white for brightness or red to preserve night vision.)
3) how many LEDs do you want.

I got a flat square led for its ease of mounting on a circuit board. My led was white because I wanted the clean white light. I only got one led.

Choosing a resistor.

You may ask why you need a resistor, well it protects you led from the evil amps that come to destroy it. Also it can help preserve your battery life. To find the right resistor I use this calculator . It calculates the MINIMUM ohm's needed keep your LED happy when electrons com zooming into it. There is no problem with using a more powerful resistor. Than you need. All the specs that you need to plug in should be on your LED packaging. if using LEDs in a series ( one right next to the other) add up the forward voltage NOT the amps.

Step 3: Gut the Lamp

Remove all the stuff you don't want. For me that included an old lamp, some copper pieces and a plastic thing that worked as the switch. you can throw all this away. Don't forget to remove the batteries, but don't throw them away they may still be good. If you feel that you need to keep something in the headlamp, do it. I also like to salvage electronic parts, they can be very useful later.

Step 4: Make the Holes

Put the holes where you want them. For me I wanted a hole on the top of the lamp for the switch and on the side of the battery pack for the POT. I also used a knife to make the holes bigger and to make a little indent for a piece on the POT that is suppose to keep the whole thing from turning while you turn the knob. Don't forget to measure and mark! When you measure the diameter of your POT and switch, go one size up. Things like that should come with nuts and washers that will keep it in place, you don't use the threads on the components. If you do make the holes too small, use a sharp knife and whittle away at the plastic.

Step 5: Place, Solder, Repeat

I started on my LED and resistor, I first soldered my wires to the board. Next came my resistor, and finally the led. After I finished I soldered my 9 volt battery to the POT. Then I soldered the POT and battery to the headlamp wires already in place (after cutting and stripping the wires already in the headlamp). then I tested the polarity of the wires, because LED's can only go in one way. Then I marked the negative side and soldered in the push button switch, afterwards I hooked it all up to the original wires inside the headlamp. A rule I use is to connect the resistor the positive side of the LED. It helps me to know which side is positive without having to feel for the tiny bump on the led to find the negative. To see which way everything goes take a look at the pictures.

Step 6: Testing and Troubled Shooting / Closing Remarks

Testing and trouble shooting

If your light doesn't turn on 
look to see if there are...
1)any bad connections
2)any wire points or solder bridges (the things used to connect wires on the Circuit board) that aren't suppose to be touching are touching.

If your light won't turn off...
Look to see if there is a short circuit between the wires on the switch.

If you light won't adjust...
Look to see if there is a short circuit between the wires on the POT

If your light sparks or speaks to you...
call the ghost busters and check for steel wool on the 9V battery leads.

Closing remarks

Now enjoy your new headlamp with brightness control! If you have any questions or have anything I need to add just leave something in the comments.