摘要:
In a circuit including a semiconductor switch for switching a load current, the so-called storage time of the semiconductor switch, i.e. the delay occurring during switching from the conductive state to the blocking state, is regulated so as to decrease undesired variation of same, i.e. the storage period is maintained substantially constant. This is achieved in the case, for example, of a transistor in that, dependent on the collector voltage, the control or base current for switching on the transistor, and possibly a reverse base voltage applied to block the transistor, are varied so as to maintain the storage period at a desired value.
摘要:
A method of, and device for transmitting a pulse-duration modulated signal wherein information is contained in the position of pulse edges in the signal comprising, amplitude modulating a first carrier oscillation with the pulse duration modulated signal to form a first carrier frequency pulse train wherein the pulse duration does not always correspond to an integral number of carrier oscillation periods, and amplitude modulating a second carrier oscillation with the pulse duration modulated signal in phase opposition to the modulation of the first carrier oscillation to form a second carrier frequency pulse train wherein the pulse duration does not always correspond to an integral number of carrier oscillation periods, the start of the first and second carrier oscillations by the pulse duration modulated signal being in phase with each other, and the end of one of the first and second carrier oscillations being separated from the start of the other of the first and second carrier oscillations to prevent a distortion of one of the first and second carrier oscillations by the other of the first and second carrier oscillations.
摘要:
The isolating transformer has two windings galvanically separated from each other and each connected to a respective point, which points are set at various high voltage potentials. At least one additional transformer is provided in series with the isolating transformer, and has two galvanically separated windings, with one winding being galvanically separated from the isolating transformer and the second winding being galvanically connected to a first winding of the isolating transformer. The second winding of the additional transformer is connected to one of the points and is split relative thereto in a manner such that a parasitic current produced between the two windings of the isolating transformer, and which is split with component currents flowing to both terminals of the first winding of the isolating transformer and therefrom to and into the split second winding of the additional transformer, produces, in the additional transformer, partial current flows which are mutually compensating to at least a great extent in their effect on the one winding of the additional transformer. Preferably two additional transformers are provided in series with the isolating transformer, each being operatively associated with a respective winding of the isolating transformer. One winding on one additional transformer is connected to the input and to ground, and one winding on the other additional transformer is connected to the output of the device. Each additional transformer may be a compensated transformer with one toroidal core, a compensated transformer with two toroidal cores, or a double compensated transformer with two toroidal cores.
摘要:
In a transmitter of amplitude modulated single sideband signals, which transmitter includes an output stage connected to receive, and effect substantially linear amplification of, a single sideband input signal, the output stage having a nonlinear gain characteristic, and a reactance network tuned to the single sideband frequency and connected to the output of the output stage, the transmitter is further provided with a control system connected to the output stage for controlling the current flow angle at the output stage output in a manner to increase the current flow angle as the amplitude of the input signal decreases, and the control system is constructed and connected for controlling the output current flow angle in a substantially synchronous, undelayed and hysteresis free manner as a function of the envelope of the single sideband input signal and for varying the output current flow angle down to values corresponding to class C amplifier operation for the highest single sideband input signal amplitude.
摘要:
A modulation amplifier having an output amplifier element which contains an accumulation choke, a switching tube and a low-pass filter connected in series, with a commutation diode connected to the switching tube is disclosed. The switching tube is controlled by pulse duration-modulated pulses and a semiconductor switch is connected between the switching tube and the pulse duration-modulated pulses. The semiconductor switch comprises two branches, each of which are connected to a different electric potential and each including a controlled semiconductor which acts as a switch, one of the branches being controlled into a conducting state and the other of the branches being controlled into a non-conducting state upon a potential jump in the pulse time-modulated pulses in either the increasing or decreasing directions. The modulation amplifier may further include a control circuit for stabilizing at least one of the potentials, which comprises a switch element as a primary control element which is controlled by an auxiliary pulse duration-modulated signal. A chopper is provided with following filter means for providing an actual value to be fed to the control circuit, which is derived from the output voltage of the filter means.