Introduction: 9 - Volt Headlamp

 This instructable will show you how to construct a simple and easy to use headlamp. I have decided to run the headlamp on 9 volts, which provides a bright white light used in this project. This project is a good starter project for those who are beginning to solder, and yields a useful reward when finished.

The headlamp will produce white light, however, it is also possible to replace the white LED's with other colors if you so desire. The LED's will be wired in parallel, so that each LED produces the maximum amount of light possible.

*Tape up your exposed connections in this project with electrical tape. 
*Use a dry-erase marker to mark positions, because it rubs off if you need to adjust the position.
*Handle soldering irons and hot glue guns with caution - They are hot!
*Build the circuit on a breadboard to make sure it works and that your components work too.

Step 1: Components and Pieces

 Depending on where you go to buy the components, you can build this project for under $10.
You will need:

2 - high intensity white LED's (3.2 volts is common)
1 - customizable printed circuit board
2 - 470 ohm resistors (yellow, purple, brown in resistor color code)
1 - slide or toggle switch
1 - 9 volt battery plug
1 - 9 volt battery
1 -  small project box (can be a mint tin, I use a $0.59 battery box from Fry's electronics).
1 - headband 
3 - (separate pieces) 6+ inches of electrical wire (can be any gauge) or a spool of wire if you have         one.

To build the light, you will use:
A soldering Iron
Electrical Tape
Hot Glue

*I recommend buying your tools and components at Fry's or Radio Shack. Use a combination of components from both stores to take full advantage of pricing differences.

Step 2: Mounting the Switch and the LED's

Solder the Led's to the printed circuit board such that they are equidistant from the edges of the board. Make sure you have the anodes and cathodes of the LED's facing the same direction (negative sides of LED's face same direction). 

Cut a notch (or drill a hole) in the housing of the project box. Place your switch such that the toggle part of it is protruding from the box housing. Secure the switch in place with a few drops of hot glue. Make sure that the leads of the switch are still exposed so that we may be able to solder them later.

Step 3: Solder Resistors and Connection Wire

Solder one end of the first resistor to the negative lead of the first LED. Repeat this step for the other resistor and LED. Then twist the other two leads of the resistors together. Twisting the leads together allows us to wire the LED's in parallel.

Connection Wire:
Cut one of your 3 wires into two sections each about 1.5 inches long. Strip the ends of each wire about a quarter of an inch. Then solder one end of the first wire to the positive lead of the first LED. Repeat this with the other wire and other LED. Then twist the other ends of the wires together. This should complete our parallel wiring of the LED's.

Step 4: Setting Up the Battery Pack

 Take the 9 volt battery plug. The leads of the plug will need to be lengthened. To do this, take your 2 unused pieces of wire (equal length), and solder one end of each to both leads from the battery plug (one wire to the negative, one wire to the positive). Cut a notch in the project box such that the wires from the battery may fit in it (you could drill a hole and feed the wires through as well). 

Step 5: Soldering the Switch and Making Connections

Take the twisted leads of the resistors. This is our negative line from the LED's. Solder the resistor leads to one terminal on the switch (the output terminal). Solder the negative wire from the battery to the input terminal of the switch. 

Solder the wire from the positive lead on the battery to the twisted ends of the wire from the positive terminals on the LED's.

The circuit is now fully wired up.

Step 6: Mount the Light in the Project Box

 Drill two 5mm (13/64 in.) holes in the project box such that the LED's may fit through snugly. This will leave the LED's somewhat exposed, but it also maximizes the output of the LED's. If you are worried about durability, you may secure the LED's in place with some clear tape, or a little hot glue. 

After you mount the LED's in the holes, secure the printed circuit board in place with hot glue in the corners. Thread the battery wires through the notch in the box that you cut earlier, and close up the box. Then glue the box to the headband, making sure that the switch and LED's remain exposed for use. You can secure the battery in place by glueing it to the head band, or putting the battery in a bag that is fastened to the headband. Enjoy your new headlamp!