Purchase or download a condenser microphone circuit schematic from an Internet resource. The schematic is your guide to the construction of the condenser microphone. If you have no experience reading circuit schematics then there are various resources explaining what the symbols mean (see Resources).
Use your circuit schematic as a parts list and purchase the electrical components represented in your schematic and a blank circuit board. Purchase the electrical components in an electronics store or Internet retailers such as Centerpointe Electronics, Digi-Key Corp. or All Electronics Corp (see Resources).
Insert your components into your circuit board, bending the connectors to keep the components in place. Orient the components as displayed in your circuit schematic.
Solder your components into place by heating the connectors with the tip of your 25 Watt soldering iron at the joint of the circuit board and the connector for one to two seconds. Once the component connector is heated feed a small amount of your Rosin core solder between the head of your soldering iron and the joint. Repeat this process for all component joints.
Use the wiring pencil to draw the connections between components directly onto your circuit board as represented in your schematic. A wiring pencil works similarly to a soldering iron, drawing a thin strip of conductive copper directly to your circuit board.
Enclose your microphone's exposed electronic components in either a project box, a plastic or metal box made to house small electronics projects, or spare microphone casing. Keep the actual microphone head outside the enclosure. Project boxes are available from electronics retailer or Internet retailer (see Resources).