Guitar Humbucker Wire Color Codes | Guitar Wirirng Diagrams Guitar humbucker wiring diagrams that show the coil winding start and finish wire colors, Seymour Duncan '59 Humbucker-4 Conductor-Bridge. The 59 Model bridge pickup is a full sounding, versatile PAF style humbucker with an articulate treble attack, full bottom end, 2, 3, and 4 Wire RTDs: What is the Difference? A 2 wire RTD configuration is the most useful with high-resistance sensors or in applications where a great deal of accuracy is not required. 3 wire RTD connections The 3 wire RTD configuration is the most commonly used RTD circuit design and can be seen in industrial process and monitoring applications.