Transformer heating refers to the way in which the soldering iron generates the heat required for soldering. The basis of this tool, often called a "transformer soldering iron", is a built-in transformer. This converts the electrical voltage from the socket to a very low voltage but very high current. This high current is fed directly into the soldering tip, which takes the form of a small metal loop. It is the passage of this current through the loop that causes it to heat up very quickly to working temperature within a few seconds. The heating is activated by pressing a switch and when the switch is released, the tip cools down again quickly. Due to the transformer principle, a magnetic field is created around the tip, so this type of heating is not suitable for soldering electronic components sensitive to magnetism. It is mainly used for fast soldering work on more robust connections where precise temperature control is not necessary and the presence of a magnetic field does not bother.
