12 volt varyable power supply

This is not the best way to build a power supply but it is easy to build and design. It is based on the well known theory of a voltage divider. This is a good low cost power supply for beginers.

Step 1 Parts and tools

PARTS
2) pairs of plugs (one pair black and one red)
2) thick wires (red and black)
2) bolts (if needed)
1) four foot segment of solid strand wire
1) 681 ohm resistor (google voltage divider if can't get)
1) switch
1) roll of electrical tape or heat shrinking tubes
1) perf board
1)Computer fan
1) Project box
1) 5k ohm potentiometer
1) roll of solder
1) 12 volt adapter
TOOLS
wire stripers
wire cutters
needle nose plyers
soldering iron
Voltage meter
Hot glue gun with glue
If needed
Drill
drill bits
work gloves (highly recomended for soldering)