Abstract: A power source, a primary inductor, a load capacitance, and one or more tuned branch resonators and switching devices are coupled to generate pulses which represent a superposition of sinusoidal waveforms. The primary inductor is connected between the power source and the load. At the start of each cycle the load is coupled to ground and each tuned-branch resonators is reinitialized to re-energize the circuits and to stabilize the waveform when the frequencies of the sinusoidal waveforms are non-periodic.

Abstract: A power source, a primary inductor, a load capacitance, and one or more tuned branch resonators and switching devices are coupled to generate pulses which represent a superposition of sinusoidal waveforms. The primary inductor is connected between the power source and the load. At the start of each cycle the load is coupled to ground and each tuned-branch resonators is reinitialized to re-energize the circuits and to stabilize the waveform when the frequencies of the sinusoidal waveforms are non-periodic.

Abstract: An oscillation maintenance circuit for a half-duplex transponder that has an LC resonant circuit, a storage capacitor and a rectifier connected to charge the storage capacitor with a rectified oscillation signal, having an end-of-burst detector providing an end-of-burst signal when the amplitude of the oscillation signal has dropped below a predetermined threshold. A clock regenerator provides a clock signal derived from the oscillation signal. Switching means controlled by the clock signal in the presence of the end-of-burst signal connect the storage capacitor with LC resonant circuit through at least one current limiting resistor during part of the period of the clock signal, in such a manner that energy is fed into the LC resonant circuit.

Abstract: A power source, a primary inductor, a load capacitance, and one or more tuned branch resonators and switching devices are coupled to generate pulses which represent a superposition of sinusoidal waveforms. The primary inductor is connected between the power source and the load. At the start of each cycle the load is coupled to ground and each tuned-branch resonators is reinitialized to re-energize the circuits and to stabilize the waveform when the frequencies of the sinusoidal waveforms are non-periodic.

Abstract: A modulated Class E oscillator. In one embodiment, the modulated Class E oscillator may achieve high coil currents (about 1A) and voltages (about 500V) with low power components. Current may be injected when the oscillating current in the inductor passes through zero. A detector circuit may be used to trigger the current injection at the appropriate instant regardless of changes in the resonant frequency of the system. Its phase can be adjusted to compensate for propagation delays in the drive circuitry, while amplitude modulation is accomplished by switching in additional reactive conductance to increase the current injected into the tank circuit. Frequency modulation is accomplished in an alternate embodiment. The oscillator can also lock to an external reference signal and be phase modulated.

Abstract: A modulated Class E transmitter is disclosed. In one embodiment of the invention, the modulated Class E oscillator achieves high coil currents (˜1A) and voltages (˜500V) with low power components by precisely timed injection of current when the oscillating current in the inductor passes through zero. A detector circuit is used to trigger the current injection at the appropriate instant regardless of changes in the resonant frequency of the system. Its phase can be adjusted to compensate for propagation delays in the drive circuitry, while amplitude modulation is accomplished by switching in additional reactive conductance to increase the current injected into the tank circuit.

Abstract: In a circuit assembly for generating pulses sustaining or “plucking” RF oscillations in a resonant circuit (12) of transponder (10) having no battery power supply in which the supply voltage needed for its operation is obtained from a RF carrier oscillation pulse defined in time exciting the resonant circuit into oscillation and used to charge a storage element whose charging voltage forms the supply voltage, a plucking pulse is generated every time the amplitude of the RF oscillations drops below a defined threshold value and its momentary value is in a defined relationship to a reference voltage (VPEAK) changing in time as the charging voltage of a capacitor (70). A switch (24) is provided which can be switched on for the duration of the plucking pulse (PLUCK) for connecting the storage element (20) to the resonant circuit (12).

Abstract: An apparatus having a radio frequency resonator, which has a coil, a capacitor means and at least one switch means being associated with another capacitor means, a resistor means and a high voltage supply means, one end of the switch means being connected to a junction of the coil and the capacitor means where a radio frequency voltage is provided, another end of the switch means being connected to ground with said another capacitor means and to the high voltage power supply means with the resistor means.

Abstract: A circuit arrangement is provided with a controlled switch which is controlled by means of a periodic switching signal for operating an oscillation circuit at a frequency f, and with a control circuit for generating the periodic switching signal. The control circuit comprises a pulse width generator for generating a periodic square wave signal with a half cycle duration which is adjustable in steps of a value T and which has a value of at least t. The circuit arrangement is characterized in that, with 2*(t+N1*T)<1/f<2*(t+(N1+1)*T) in which N1 is an integer number, the periodic switching signal is built up from a repetitive chain of square wave signals with a repetition cycle which comprises n1 half cycles of a duration t+N1*T and n2 half cycles of a duration t+N2*T, wherein N2 is >N1 and is an integer number.

Abstract: In a cordless, electro-magnetic digitizing system having a drive circuit outputting a square wave drive signal of known initial polarity to a transducer coil in a cursor to oscillate the transducer coil and cause a magnetic field output therefrom which is detected in an associated tablet, a method of operation and associated apparatus for determining the phase of a response signal induced by the magnetic field from the response signal itself.

Abstract: A circuit arrangement is described with the aid of which a control signal can be generated in dependence upon the occurrence of an extreme value of a sinusoidal oscillation. The circuit arrangement (10) includes a storage member (22) which is adapted to be charged via a diode (20) to one of the extreme values of the sinusoidal oscillation. A discharge path (26) for the storage member (22) is present, the time constant of which is so dimensioned that within the period duration of the sinusoidal oscillation an appreciable discharge of the storage member (22) takes place. A switch element (24) controllable by the charge voltage of the storage member (22) furnishes the control signal at its output (14) for the period of time during which the charge voltage at the storage member (22) is smaller than the extreme value of the sinusoidal oscillation. The circuit arrangement can be used in maintaining the oscillations of a resonance circuit stimulated to oscillate by means of a momentary HF carrier wave pulse.

Abstract: An adjustable output level transmitter includes a direct current energy source, an L-C tank circuit and a switching means for sequentially coupling the capacitors of the tank circuit to the direct current energy source and ground. The output signal frequency is equal to the resonant frequency of the L-C tank circuit and the output signal level is a function of which capacitors of the L-C tank circuit are sequentially coupled to the energy source. The circuit functions in a Class D mode with the inherent advantages of minimal power loss and very high efficiency. Due to the manner of switching utilized, the output signal frequency is very stable and unaffected by the mode of capacitor switching.

Abstract: An oscillator circuit for use with a supply line and a line at a reference potential includes a crystal and a switching stage, the switching stage being closeable to connect the crystal to the supply line via one terminal of the crystal. The other terminal of the crystal is connected to the line at reference potential. Closing of the switching stage is controlled by a drive unit, which has an input to which the output of the switching stage is fed back. The drive circuit causes the switching stage to be briefly closed during a half period of the oscillation. If the oscillator circuit is manufactured as an integrated circuit, only one terminal pin is required for connection to the crystal, thereby saving space.

Abstract: A device for use as a self-oscillating Class D transmitter is disclosed which uses feedback to maintain the oscillation at the resonant frequency of the device, thereby optimizing the efficiency of operation and overcoming the frequency mismatching inherent in previously known transmitters. The device uses a series LC combination which is driven by a comparator and a tri-state logic driver, with a feedback loop using a differentiator used to switch the polarity of the square wave generator. The system thus self-oscillates at the resonant frequency of the capacitor and inductor, even when the inductance of the inductor is varied by the inductor coming into close proximity to another inductor.

Abstract: A frequency set-on oscillator comprises an input switch (12) an amplifier (22) and a delay line (16). A frequency divider (14) having two outputs is provided in line with the input switch (12). The two outputs of the frequency divider are connected to a mixer (20), one of the outputs containing the delay line (16). The output of the mixer (22) is fed to the amplifier (22) and the output of the amplifier is fed back to the input switch (12) via a bandpass filter (24). The device of the invention is a very simple network configuration capable of sustaining a desired frequency for very much longer periods than has been possible with previous devices.

Abstract: A method of and apparatus for exciting harmonic generation of radio frequency in a tank resonant circuit by bipolar spaced, half-cycle pulses, wherein the period of the tank resonant frequency oscillations is 1/N the period between successive pulses of similar polarity, where N is an odd integer greater than unity.

Abstract: A proximity sensor oscillator is disclosed having controlled charge. The proximity sensor oscillator includes a resonant circuit which oscillates at a frequency determined by the components of the resonant circuit and with a power loss that is inversely related to the distance that a sensor element of the resonant circuit is to a conductive object. The peak amplitude of the resonant circuit varies with power loss and therefore measurement of this parameter provides an indication of the proximity of the conductive object to the sensor element. Power is provided to the resonant circuit by metering a fixed charge to the resonant circuit just before the peak of the resonant circuit voltage by means of a transistor switching circuit.

Abstract: A process, and the article produced thereby, for providing a uniformly and tenaciously adhered abrasion resistant and chemical resistant non-opaque coating on polycarbonate articles. The process comprises priming the surface of the polycarbonate article with an adhesion promoting thermoplastic acrylic polymer by forming a thin film of said thermoplastic acrylic polymer on the surface of the polycarbonate article, applying a silica filled organopolysiloxane coating composition onto the primed polycarbonate article, and thereafter curing the silica filled organopolysiloxane to form a hard, abrasion and chemical solvent resistant top coat which is tenaciously adhered to the polycarbonate article. The non-opaque coated polycarbonate article produced by this process comprises a polycarbonate substrate having (i) a primer layer comprised of a thermoplastic acrylic polymer, and (ii) a thermoset silica filled organopolysiloxane top coat.

Abstract: A circuit is provided for synchronizing the oscillation U.sub.o of a pulsed oscillator with a reference oscillation U.sub.m of comparatively small amplitude. The reference oscillation is coupled into the oscillator and a phase control loop is provided in which a phase discriminator compares the phase relationship of both oscillations and provides a resulting control voltage for controlling an adjustable reactance for the frequency change of the pulsed oscillator during the leading edge of the pulse. A phase shifter, adjustable up to 180.degree., is connected between the oscillator and the phase discriminator. The output of the phase discriminator, which is highly resistive, is connected in a low-resistance manner to the adjustable reactance by way of an impedance converter, such as an emitter follower or a multi-stage wide-band amplifier.

Abstract: A tuned circuit resonates to produce a ringing signal. The signal is fed to frequency divider which generates an oscillator output pulse. The pulse is fed back to the tuned circuit for impulse excitation thereof, producing subsequent oscillator output pulses.