Materials:

• 1-3 LEDs of any color. I suggest red, green or white.
• resistor rated for 6.9 volts at required current for LED’s being used.
• dead 9v batteries. You may need a few different brands to find the part you like.
• a good 9v of course.
• JB Weld or something similar.
• tape or small piece of non-conductive material

Tools:

• Wire cutter / sharp scissors
• Soldering iron
• uhh… a stick
• helping-hands, alligator clips or even a pair of hemos would he helpful but aren’t a requirement.

For our example we will be using 2 white LED’s.

1. Find the proper resistor.
   Go to the following website http://led.linear1.org/led.wiz and calculate the required resistor for your LED configuration. Calculate your forward voltage at 6.9 instead of 9v. I find this number gives you a nicer light once the battery starts to die off. I also use a bit higher current than the manufacturer recommends. The process to find this number is by using a bunch of resistors to find the sweet spot in the LED. Problem with this concept of thinking is that almost every LED is different. So I usually just add 5 – 10 ma higher.You can ignore this of course and stick with the manufacturers suggestions if you wish.

   Example: Using 2 white LEDs with a manufacturer rating of 3.2 volts and 25 ma we fill the calculator. Of course we are using 6.9 volts as source voltage and upping the manufacturer suggested 25 ma to 30 ma. The calculator shows us that we need to use a 18 ohm 1/4w resistor.

2. Solder your LEDs.
   When soldering LEDs together one should always make a jig of some sorts. I tend to use cardboard or Styrofoam. Put a small hole in either medium with a pencil or screwdriver and firmly yet carefully to avoid damaging the leads push the LED into place. Do the same with another about 1/4 inch from the center point of the first. Rotate until the leads are lined up in a straight line in alternating order, long – short – long – short. Using needle nose pliers bend the center two leads towards the other about 1/4 inch from the actual LED. Solder these together and clip your tails. Once you have that carefully twist the resistor onto the shorter of the remaining leads as close to the LED as possible making sure to get at least one wrap around the LED lead. Solder these together and clip your tails.

   

   

   

   

3. Remove battery casing.
   Carefully remove the battery casing using your pliers. Start at either side of the seam on the edge of the battery. Grab the outside edge were the seams come together and carefully pry and peel away the battery casing. It should be done in one piece, just take it apart at the seam. Once the casing is removed pull the terminal board away, refraining from putting pressure on the board side of the leads. Clip the leads as close to the “aaaa” battery pack as possible.

   

   

   

4. Solder LED Circuit to terminal board.
   Cut out a piece of plastic or even use a small cut piece of electric tape or other similar non-conductive material. Place it covering the the terminals on the side the resistor will be connected. Glue or stick into place. Using the sharp point of a knife scratch the terminals so that there is something for the solder to grab on. Solder and clip your tails.

   

   

5. JB Weld it all together.
   Prepare your JB Weld and wait until it really starts to thicken. At first when you mix the JB Weld, it will be like a nice creamy peanut butter. Wait until its like a think molasses. This will allow you to work with it better. Carefully using your stick spread the JB Weld all over the top of your LED circuit and the terminal board. Make sure to get in all the little nooks and crannies and try not to get any on the battery contact side of the board. Let it sit for a moment or two allowing the JB Weld to settle. You may find that in areas it has settled thinner than others. Just apply a bit more JB Weld to that area. Do not worry to much about it being smoothed out at this point, it will settle in. Your more likely to mess it up trying to smooth it by hand. Let it dry over night and its good to go.

   

   

Tips:

• Remember to use flux when soldering. Also be in a well ventilated area.
• Have a dead 9v lying around with some tape wrapped around it if you plan on building a few of these. It really helps having something to hold onto.
• You can of course arrange the LEDs however you wish. I choose to lay them on their side to reduce space taken and provide a little lantern if i stand the 9v on end.
• When using it you can connect the light to the battery only using one terminal, then swivel the light around to act as a on-off switch.

I am basing my regulation circuit off a LM317 3 Terminal regulator. It may be a very simple circuit but I haven’t come across it in this application. In fact the circuit is taken from the data sheet.

I will be providing the full plans on how to make your very own USB Variable Power Supply. Please check back regulary if this project interests you.

So I searched for a bit and relazed that the cheap benchtop power supplies are just that, cheap. To get something of value, I would need to spend around 100 dollars to get a basic benchtop that wasn’t garbage.

That kinda sucks.

I need something cheap for my first power supply yet still useful. My google-fu led me to several how-to articles and half-assed instructables that would provie me exactally what I needed, a ATX power supply converted to a benchtop power supply.

The following articles greatly helped me: