Hi friends, in this instructable, I am going to show you how I made a portable power supply which can be used as a tool for hobby projects, of course there are power supplies like this in instructables site, but this one has three advantages, 1) being pretty and has a good appearance and 2) it uses lap top discarded batteries i.e. 18650 lithium ion type, which are free and can be used for such cases, 3) it has a led when you switch it on and indicates that the battery is connected and device is ready for use, so for those of you that want to make a cheap project with a few dollars and enjoy your handmade device will be a true fun. Hope you like this simple project.

Step 1: What You Need

For making this simple project, you need the materials and components as follows:

1- A plastic container such as mask, cream or capsule or similar containers and a cylindrical support, which I used a perfume container cap which is big enough the dimensions of cream container and the support are as follows: 9.5 cm(diameter) * 8 cm(length) which is tapered to 7 cm(diameter) and the support is 7 cm (length) * 5.5 cm (diameter).

2- Three lithium ion batteries(18650) which could be salvaged from a discarded laptop battery pack, then connect them in series and pack them like what you see in photo, use paper tape to stick them together and make a pack.

3- Step down voltage regulator: unfortunately I could not find :Boost Buck DC adjustable step up down Converter XL6009 Module , therefore I decided to use two modules one booster module, which I found, a CN6009 module for that, then I thought because my battery package is 12 V , and since I usually use less than 12 volt voltages - after my CN6009 burnt!- I used a step down module i.e. LM2596 DC to DC step down regulator, adjustable +1.23 to 35vdc output, 2A

4- A 10K OHM Linear Taper Rotary Potentiometer Pot

5- A Black 15mm Knurled Shaft Potentiometer Control Knobs

6- A red LED

7- A 1 k Ohm resistor

8- A CDE 12V Coil 12 Amp Relay Rated at 125 VAC - Small / Light 12 V Relay

9- A Mini Blue DC 3-30V LED Panel Voltmeter 3 Digital Display Voltage Meter 2Wires

10- A DC Power Supply socket Jack Female Outlet Charger Connector 5.5mm x 2.1mm

11- Red+black Binding Post Female Socket Jack for 4MM Banana Plug Connectors

12- Pair of Multimeter Voltmeter Test Probe Leads with Banana Plug Connectors

13- A small piece (3cm*3cm) perf board

14- 4 small screws

15- A 2 Pin 12V Car Boat, ON/OFF Rocker Toggle Switch

Step 2: Tools Needed

1- Soldering iron and solder

2- Small drill

3- Super glue

4- Wire stripper

5- Small and medium size screw drivers

6- Cutter

7- Plier

Step 3: How to Make

Making that is very easy as follows:

1- make rectangular holes with the dimension of rocker switch and LED on the cylindrical support, the best method is first draw the rectangle and then make holes with the small drill on that, and then cut through the holes with the drill until a piece get separated and then use the cutter (carefully!) to trim it to the drawn rectangle, the hole for the LED is just simple drilling practice, another big hole you should cut is the diameter of the cylinder on the main container, in this case you first draw it and then make many holes and interconnect the holes with the drill, and then use the cutter to trim it and make it suitable for the support to be inserted inside the main container.

Other holes are 1 rectangular hole on the cap for inserting the voltmeter, two round hols on the cap for the female banana jacks, a round hole for the stem of potentiameter on the container body, and a small rectangular hole in the back of container for fixing the female charging jack, same technique should be applied for these holes.

2- Now all holes are made and you are ready for the electronic parts, first, use the above diagram to connect the battery to the relay and rocker switch and the LED. a 1 k Ohm resistor should be soldered in series with the LED, insert the battery pack, and the circuit you've just made inside the support and insert the support in to the container.

3- Take the LM2596 DC to DC step down regulator and use soldering iron to remove its potentiometer Trimpot Variable Resistor, and replace it with the potentiometer which was described above with three wire and soldering them together.

4- solder two short wires to the female charging jack and inser it in to the hole on the back of the container and make two small holes for screws and tighten the screws.

5- insert the voltmeter in side the rectangular hole on the cap and make two small holes for screws and tight them, also insert the Red&black Binding Post Female Socket Jack in their holes and tighten their nuts, and solder two short pieces of wires to those jacks and solder them to red (positive) and black (negative) poles of the voltmeter.

6- Take the small perf. board and solder the relay to that and solder four short pieces of wires to the relay terminals, be sure you use normally open terminals of the relay and coil terminals.

7- Now solder all positive and negative(earth) terminals according to the above diagram to the battery terminals and use short pieces of Electrical Wire Fiberglass Insulation Sleeving to avoid accidental connection of positive and negative polarities when inserting every thing inside the container.

8- Insert the potentiometer inside its hole and tighten its nut to be fixed.

9- insert all components inside the container and close its cap(door) and switch it on.

Step 4: Conclusion

Now, the pretty portable power supply is ready for use, it is nice, handy and useful in every sense, you don't have you take your big power supply with you when you are sitting next to your desk and you are far from working table, it is good looking and gaze at you and tells you" DEAR MAKER, START A NEW INSTRUCTABLE!" and you like its idea!...and start to make a new instructable!

Thank you very much for your kind patience!