Abstract: A self tuning control system and a method for tuning such a system. The system has a controller formed by a PI controller and a proportional control unit with a mixing point therebetween to which the absolute reference valve is connected. The system has another mixing point upstream of the controller to which the reference variable and the absolute reference valve are connected. The self tuning method involves two cycles. In the first cycle the control loop of the controller is closed only through the proportional control unit and the proportional component of the proportional control unit is determined. In the second cycle the control loop is closed through both the PI controller and the proportional control unit and the integral action time and proportional action coefficient of the PI controller are determined.

Abstract: The present invention is embodied as an arrangement for positioning a pen in a device that records the time profile of a measurement signal which can be connected to the device. The arrangement provides high mapping accuracy of the measurement signal onto the recording signal at a low cost and with DC isolation between the measurement signal and drive means of the pen. The arrangement uses a control loop that has a pulse width modulator whose output is DC-decoupled to a signal converter that provides the drive signal for the motor that moves the pen.

Abstract: A multi-channel recording device for recording the time profiles of a plurality of measurement signals which can be connected to the device. The device has first and second groups of optical indicators on the front of the device and scale strips corresponding to the physical variables to be measured. There are n indicators in the first group, m indicators in the second group and scale strips where n is greater than m. The device assigns one and only one of the m indicators to each of the n indicators.

Abstract: Nondispersive infrared gas analyzer for the concurrent measurement in the concentration of several components contained in a gas sample, and including a source of and modulator for infrared radiation, a measuring and reference chamber are traversed by said beams, at least two serially pneumatic radiation detectors each having a front and a rear chamber filled with a respective component and each provided for measuring the pressure differential between the respective chambers, a filter disposed between the first detectors upstream and having opaque range which covers at least a major absorption band of the component filling the downstream detector but having a region of transparency which includes at least one secondary absorption band of that component.

Abstract: An axially compact hair dryer includes a cylindrical outer housing 1, an air outlet 2 at one end of the housing, an air inlet grate 3 at the other end, an electric motor 4 centrally mounted within the housing and driving a blower fan 5, and a generally cylindrical electric heating element 7 disposed in the otherwise wasted annular space between the motor and the housing.

Abstract: A loudspeaker driver system linearizes loudspeaker operation by superimposing a high frequency (supersonic) signal on the low frequency (audio) signal. Features include a special crossover network for a multispeaker system, and an acoustic filter formed of perforated discs.