Abstract: A resistive load, such as a discharge lamp, is connected in a circuit which includes a measuring circuit for measuring the instantaneous power absorbed at the terminals of the load. The measuring circuit includes:measuring means for measuring a low voltage at the foot of the secondary of the transformer which supplies a high voltage supply to the load, such that the measured voltage is an analogue of the voltage across the terminals of the load;a second measuring means for measuring the current passing through the transformer secondary in phase with the measured low voltage, this measured current being an analogue of the current passing through the load;rectifier circuits for rectifying the measured current and voltage; anda processing circuit for processing the rectified signals and to produce in response to them an output signal representing the instantaneous power taken by the load.

Abstract: A high voltage generator 1 for an electrostatic dust precipitator 2 comprises a low voltage oscillator 6, operating from a low voltage continuous source, such as a car battery, which supplies a current chopper 7. The output from the chopper 7 is fed to the primary winding 9 of an induction coil 10. The secondary winding 11 of the coil 10 is connected to one of a metal surface 3 of the dust precipitator to apply a high potential difference between the metal surfaces 3,4 to precipitate dust. Preferably the metal surface 3 is connected to the secondary winding 11 via a high voltage diode.

Abstract: The invention provides a distributor device for H.T. supply to an internal combustion engine, and comprising several ignition coils and a single contact breaker to interrupt supply to one or more of those coils at any instant, each of the coils having its primary winding shunted by a thyristor which can be controlled to select whether the primary winding of that particular coil is to be energized, or not, as the case may be.In one embodiment, the thyristors are polarized so as to conduct in a direction allowing "idling" circulation of current through the closed circuit comprising the shunting thyristor and its associated primary winding; in another embodiment the thyristors are polarized in the reverse direction and a diode is connected between the gate and the cathode of each thyristor to protect the cathode from gate voltage and another diode is connected to protect the gating circuit of that particular thyristor.