Abstract: Soldering apparatus of the kind having a replaceable tip element including a soldering face and having a frame portion and a tip retaining portion adapted to retain the tip element in heat conducting relationship with the frame portion. The soldering apparatus is characterized in that the frame portion incorporates a contact assisting formation adapted to embed itself at least partly into the tip element remote from the soldering face to thereby reduce electrical resistance between the tip element and frame.

Abstract: A suction desoldering tool has an elongate handle, an elongate housing defining a bore therethrough and extending co-axially from one end of the handle solder, a collecting chamber in the handle, and a tubular heating bit holder. The holder is mounted in the end of the housing remote from the body and includes a body portion surrounded by an electric heating element for receiving the bit and a tubular portion of lesser wall thickness providing communication between the bit and collecting chamber. The tubular portion is surrounded by an imperforate sleeve which defines an insulating air space along the tubular portion to enable the full length of tubular portion to be maintained above the liquidus temperature for solder melted by the bit during a desoldering operation, so that the melted solder can be drawn into the collecting chamber through the bit and holder by a source of suction connected to the chamber.

Abstract: In an electrical soldering iron having a soldering tip which is heatable to a predetermined operating temperature by means of an electrical heater element and in which electrical heating and control circuits are provided to supply electric current to the heater element in response to predetermined changes in temperature of the soldering tip an electrically conducting sensing element is operatively connected with the soldering tip having a resistance which varies directly with changes in its temperature. The heating circuit has a controlled rectifier as a switch and the control circuit is adapted to regulate said controlled rectifier to open and close the heating circuit in response to a predetermined change in the resistance of the sensing element. The control circuit includes a bridge circuit in which a bias compensating diode is connected to compensate for bias of the controlled rectifier.