A DC chopper device comprising a DC power source, a plurality of power transistors connected in series with a controlled unit driven by the DC power source and connected in parallel with each other to make chopping operation, a chopper control unit controlling the chopping operation of the power transistors, and a base drive circuit connected between the chopper control unit and each of the power transistors. Each base drive circuit includes impedance means for discharging the charge stored in the base region of the associated power transistor when the power transistor is turned off from its conducting state, and current flow blocking means for blocking current flow through the impedance means in the conducting state of the power transistor. The impedance values of the impedance means in the base drive circuits are selected so that all the power transistors can be substantially simultaneously turned on.

Disclosed is a supply of the AC-DC converter type where the regulation is achieved by successive operations for charging and discharging a capacitor. The supply includes an input oscillator circuit, the period of which is very small as compared with that of the input AC voltage. A first switch is closed during the time necessary for the charging of the capacitor of the oscillator circuit. When it opens, a second switch gets closed to enable the transfer of energy towards the load. The regulation is done by an oscillator circuit which is controlled by an error voltage on the load and which triggers a monostable trigger circuit to close the first switch and open the second one during the period when this monostable trigger circuit is in its quasi-stable state.

This invention relates to a triangle wave generator for producing a constant amplitude triangle wave signal having a frequency proportional to an input voltage signal. The triangle wave generator is comprised of a square wave signal generating circuit to provide a square wave signal having a frequency proportional to the input voltage signal. A biased amplifier circuit is provided which has an input and an output. The input of the biased amplifier circuit receives the input voltage signal and the biased amplifier output is coupled to a switching circuit. The switching circuit is coupled to the square wave signal generating circuit to receive the square wave signal and provide a pair of square wave signals to positive and negative input terminals of a differential integrator. One of the pair of square wave signals is the complement of the other. The differential integrator provides the constant amplitude triangle wave signal which has constant amplitude and has a frequency proportional to the input voltage.

A method of sensing the rms value of a phase chopped sinusoidal electrical waveform including combining an input signal representative of the waveform with an auxiliary signal in a combining circuit which produces a combining circuit output equal to whichever is the greater of the auxiliary signal and the modulus of the input signal, and averaging the combining circuit output over at least one half cycle of the waveform. The resulting output signal level is representative of the sensed rms value. By making the auxiliary signal equal to the product of a predetermined factor multiplied by a desired value of the output signal level, a feedback signal is produced to allow control of the rms voltage delivered to a load such as a lighting circuit.

A circuit arrangement is described for supplying a load (1) from a direct voltage source (14) through a switch bridge (3 to 6), by which the direct voltage source (14) can be connected in alternating polarity to the load (1), comprising a control circuit (17) for controlling the switch bridge (3 to 6); and including a circuit for precisely adjusting and controlling a given D.C. component through the load by a device for measuring a current (I1) through the load (1) and supplying a corresponding measurement value and in that the control circuit (17) comprises an integration stage (18) for integrating the measurement value, a comparison stage (20) for comparing the integrated measurement value with a reference value (of 21) and for supplying a switching signal (at 22) when these values correspond to each other and a signal-producing stage (23) for resetting the integration stage (18) to an initial state and for reversing the polarity of the current (I1) through the load (1) upon the occurrence of the switching signal (at 22).