Abstract: In an electrodeless discharge lamp of the type including an ionizable medium within a sealed envelope capable of emitting radiant energy when subjected to a radio frequency field, an oscillator for generating an output signal at a given radio frequency, a Class D RF amplifier including first and second transistors responsive to the oscillator output signal, and an induction coil responsive to the output of the amplifier, the coil being positioned in close physical proximity to the medium in the envelope for coupling to the medium an electric field having a magnitude sufficient to initiate ionization of the medium and a magnetic field for maintaining the ionization, there is disclosed an improved transformer for driving the Class D amplifier which results in a significant decrease in power consumption. The oscillator output signal is connected to the primary winding of a transformer which includes a toroidal, magnetic core.

Abstract: In a method for the enhancement of the A.C. performance of an inductor such as a transformer or choke, the tendency of the core of the inductor to become saturated by flux arising from low frequency A.C. or D.C. currents flowing in the inductor winding is reduced by detecting the magnitude of such currents and applying to a control winding wound on the core of the inductor a compensating current in order to generate a magnetic flux in the core of the inductor which opposes the component of flux tending to cause saturation. An inductor to which the method may be applied may accordingly comprise a main winding, a magnetic core, a control winding, means for sensing the presence in said main winding of a current having a frequency below a predetermined limit, and means for applying to said control winding a control circuit tending to balance the flux generated by the sensed current.

Abstract: Improvement in free point indicators disclosed in U.S. Pat. No. 3,690,163. Discloses new strain sensing system having all electrical/electronic components, other than coil and diode components, located at earth's surface remote from high temperatures and shock loading. Includes a toroidal armature within the downhole tool having coils or windings to generate a pulsating magnetic flux field developed by an alternating current. A U-shaped permanent magnet is disposed such that a portion of its constant magnetic flux field occupies physical space common with a portion of the pulsating magnetic flux field for mutual influence. A diode provided in series with each winding limits electrical current passing through each winding to pulsating DC. The constant flux of the magnet and the pulsating flux of the coils are relatively positioned in opposing sense whereby the current passing through each winding is of designated magnitude.