Abstract: A D.C. welder includes an engine-driven D.C. generator, a polarity-revers switch which can change the direction of current flow through the field winding of that generator to provide a positive or negative polarity at the welder output terminals, a circuit that automatically permits only uni-directional current flow through that field winding during the starting of the engine, and a further circuit that energizes a solenoid to close contacts which enable that generator to operate as the starting motor for that engine but which thereafter de-energizes that solenoid and then keeps it de-energized until the engine is at, or close to, rest.

Abstract: An electric welder has magnetic cores with windings thereon which perform the functions of transformer windings as well as the functions of magnetic amplifier windings. The secondary windings, on each pair of those magnetic cores, are connected in series relation; and, similarly, the control windings on that pair of magnetic cores are connected in series relation. One of those control windings can have the voltage across it reduced to essentially-zero to cause a high voltage to be developed across the control winding on the other of that pair of magnetic cores--with consequent prompt saturation of that other magnetic core and with the development of an output pulse by the secondary windings on that pair of magnetic cores.

Abstract: The electric generator of the present invention has a plural-section main nding; and it uses uni-directional devices to permit current to flow through various sections of that winding as the rotor poles move away from various of the stator poles of that generator but to prevent current flow through those various sections as those rotor poles approach those stator poles. By preventing current flow through those various sections, as those rotor poles approach those stator poles, the present invention relieves the field winding of all need of overcoming the magnetomotive force of that main winding. As a result, fewer ampere turns are needed to enable that field winding to provide the magnetomotive force for that main winding.In some preferred embodiments of the present invention, an exciting winding has sections thereof that are wound on poles which have turns of the field winding wound thereon.

Abstract: A D.C. welder includes an engine-driven D.C. generator, a polarity-reversing switch which can change the direction of current flow through the field winding of that generator to provide a positive or negative polarity at the welder output terminals, a circuit that automatically permits only uni-directional current flow through that field winding during the starting of the engine, and a further circuit that energizes a solenoid to close contacts which enable that generator to operate as the starting motor for that engine but which thereafter de-energizes that solenoid and then keeps it de-energized until the engine is at, or close to, rest.