Abstract: An operator controllable transformer having a variable inductor with a control coil is provided. The transformer includes phase control circuitry to control the output of the transformer by phase controlling current flow in the control coil, thereby controlling the current provided to the load.

Abstract: A method and apparatus for providing an ac signal to load terminals, where the signal has a reduced open circuit voltage is disclosed. The apparatus includes an ac current source connected to the load terminals and an open circuit sensor. A control circuit is connected to the source of ac current and to the open circuit sensor, and when the sensor senses an open circuit the control circuit causes the current source to provide a dc signal. The dc signal is created by allowing the current source to provide a signal of only one polarity. The polarity may be either electrode positive or electrode negative. The current source may be either a phase controlled current source or an inverter. The method includes the steps of detecting the presence of an open circuit at the load terminals and causing the ac power source to provide a half wave signal of only one polarity in response to the detection of an open circuit.

Abstract: An operator controllable transformer having a shunt magnetic path with a control coil is provided. The transformer includes phase control circuitry to control the output of the transformer by phase controlling current flow in the shunt coil, thereby controlling the flux through the shunt magnetic path and the flux coupling with the secondary coil. Power for the control circuitry is derived from the current induced in the shunt coil.

Abstract: A transformer having a shunt magnetic path and a shunt coil is provided. The transformer includes control circuitry to control the output of the transformer by controlling current flow in the shunt coil, thereby controlling the flux through the shunt magnetic path and the flux coupling with the secondary coil. The current in the shunt coil is phase-controlled and power for the control circuitry is derived from the current induced in the shunt coil.

Abstract: A welding gun having a switch comprising two spaced apart coaxial conducting springs which act as switch contacts for completing a circuit to initiate a welding process. A coaxial flexible wall in the handle of the welding gun surrounds the two springs such that, when a welding machine operator depresses the flexible wall, the two springs make electrical contact to complete the circuit. When the flexible wall is released, the springs return to their original positions, thereby interrupting the electrical circuit.

Abstract: A fail-safe voltage reducing circuit for an arc welder. The welding transformer has two primary windings connected in parallel across a power source. After an arc is struck, if the arc is then broken for a predetermined time period, the circuit automatically disconnects one of the primary windings from the power source, thereby reducing the voltage across the welder's output terminals to a safe standby voltage lower than the full open circuit voltage. If the voltage has not been reduced after a second predetermined time period, the fail-safe feature of the circuit automatically disconnects both primary windings from the power source, thereby completely removing all power from the welder.