Soldering Pen

Discussion in 'General Electronics Chat' started by cmartinez, Jan 19, 2007.

  1. cmartinez

    Thread Starter AAC Fanatic!

    Jan 17, 2007
  2. mrmeval

    Distinguished Member

    Jun 30, 2006
    See if one of the wires is connected to the tip. It's usually done for ESD protection and is tied to earth ground.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    If there were only two wires, the resistance in the both wires would be added to the element resistance (as far as the bridg is concerend). The change in bridge voltage as a function of temperature change would be reduced.

    By adding a third wire, the entire lower half of the bridge can go into the soldering iron housing. Each side has a wire going back to the rest of the circuitry, so conductor resistance cancels out. Delta V per Delta degree is thereby maximised.