Abstract: An ionization vacuum measuring cell comprises an anode (3A) and a cathode (4K) in a measuring chamber (107). The measuring chamber (107) is arranged in a housing (101) which has a vacuum-tight feedthrough (103) for a connection rod (104) of the cathode (4K) towards the outside. The measuring chamber (107) holds the rod (104) in a feedthrough (109) which is electrically insulating only. The measuring chamber (107) in the housing (101) can be exchanged by a releasable plug connection (106).

Abstract: An ionization vacuum measuring cell comprises an anode (3A) and a cathode (4K) in a measuring chamber (107). The measuring chamber (107) is arranged in a housing (101) which has a vacuum-tight feedthrough (103) for a connection rod (104) of the cathode (4K) towards the outside. The measuring chamber (107) holds the rod (104) in a feedthrough (109) which is electrically insulating only. The measuring chamber (107) in the housing (101) can be exchanged by a releasable plug connection (106).

Abstract: A pressure sensor has a baseplate and a support plate with a membrane. Layers on the membrane and the support plate are connected to a circuit for capacitively measuring pressure to generate a first pressure signal. A thermal conductivity measuring element that generates a second pressure signal has a heating element connected to the baseplate adjacent the support plate at a location opposite from the membrane for protecting the membrane from thermal effects. The method uses the sensor apparatus to generate an output signal representing a measured result when the measured result is above a transition value, on the basis of the first pressure signal and, when the pressure falls below a threshold value, any offset of the first pressure signal is compensated in such a way that determination of the output signal on the basis of the first pressure signal leads to the same result as determination of the output signal on the basis of the second pressure signal.

Abstract: Two resistance elements (3, 6) are used for eliminating the influence of wall temperature on the gas pressure in a vessel, determined by a Pirani manometer. The first resistance element (3) is present in a first branch of a Wheatstone bridge (1), and the voltage is tapped by means of a voltage divider (7). The second resistance element (6) is present with a series resistance (5) in the second branch and is adjusted to a lower temperature. The changes in the voltages tapped at the branches are essentially identical for identical temperature changes at the resistance elements (3, 6), so that the Wheatstone bridge (1) remains balanced. The adjustment is improved by a constant current source (11).

Abstract: A pressure sensor has a baseplate and a support plate with a membrane. Layers on the membrane and the support plate are connected to a circuit for capacitively measuring pressure to generate a first pressure signal. A thermal conductivity measuring element that generates a second pressure signal has a heating element connected to the baseplate adjacent the support plate at a location opposite from the membrane for protecting the membrane from thermal effects. The method uses the sensor apparatus to generate an output signal representing a measured result when the measured result is above a transition value, on the basis of the first pressure signal and, when the pressure falls below a threshold value, any offset of the first pressure signal is compensated in such a way that determination of the output signal on the basis of the first pressure signal leads to the same result as determination of the output signal on the basis of the second pressure signal.

Abstract: Particularly for the combination of cold-cathode ionization sensors and Pirani sensors, for obtaining a one-to-one measuring range which is significantly expanded compared to the measuring ranges of the respective sensor types, a weighting technique is provided in a transition range .DELTA.P of the respective sensor measuring ranges by which the characteristic sensor curves can constantly be guided into one another in a one-to-one manner.

Abstract: A method and apparatus for convening a measured signal which, at least in a first approximation, is related to a quantity of interest by the equation (a): ##EQU1## where y is the quantity of interest, x is the measured signal, and k, k.sub.N, k.sub.Z are constants, into a signal that is a function of the quantity of interest. The method implements the function (b):ln y=prop. ([ln (x-k.sub.N)-ln (k.sub.Z -x)])wherein prop. means proportional, and where the function is implemented in an approximated manner by at least two bipolar transistors that have base emitter voltages that are dependent on collector currents of the bipolar transistors for receiving an output signal according to the equation (c): y'=ln y, with y' being the output signal.

Abstract: A process for measuring pressure, preferably vacuum is described. The measuring signals from a heat conduction gauge and the measuring signals from a gas friction gauge are processed to a common measuring signal preferably by multiplication. They are linearly superimposed or added. The heat conduction gauge is preferably a Pirani gauge and the gas friction gauge is preferably a tuning fork quartz gauge.

Abstract: In the present pressure measurement process the damping signal of a tuning fork quartz manometer, which is a measure of the prevailing pressure, is so combined with the correction value proportional to the resonant frequency that a measurement result is obtained, which is independent of any contamination of the tuning fork quartz. Apart from the resonant frequency (f.sub.R) of the measuring quartz (11), preferably also the resonant frequency (f.sub.R ') of a reference quartz (21) kept at constant pressure is determined. Thus, the damping signal (R.sub.S) can be corrected by a correction value proportional to the difference between the two reference frequencies (R.sub.R '-f.sub.R), which is substantially temperature-independent.

Abstract: The tuning fork quartz manometer has a tuning fork quartz (2) mounted in a protective casing (3) which is in turn part of a self-oscillating feedback circuit. According to the invention the protective casing (3) is inserted by means of a sealing compound (4) or directly into a hosing (5) of a measuring head (1,6) or a mounting support (15a, 20') so that the mounting support can in turn be inserted in the measuring head (1,6) and, as desired, an ideal rigid or elastic suspension is provided. A measuring circuit (20) is located directly in the measuring head close to the tuning gork quartz (2) and is thermally coupled to the latter. The measuring circuit (20) preferably has a temperature correction network (R.sub.1, R.sub.2, 22) high frequency coupled from the feedback circuit containing the tuning fork quartz.

Abstract: Conventional electrical scales having independent weighing channels for a reference weight and the actual load with subsequent division of the resulting load signal by the reference signal to furnish the final output cannot furnish a final output signal independent of accelerating disturbances in a large critical frequency region, since changes in load change the dynamic behavior of the load channel. To substantially decrease variations in the final output signal due to such accelerating disturbances, the load signal is additionally coupled to the reference channel by means of at least one frequency-dependent network.

Abstract: An improved weighing apparatus of the electromagnetic load compensation type is disclosed, including a correction loop connected between the output terminal of the synchronizer and the input terminal of the pulse length modulator for varying the regulated load signal from the PID regulator to produce a corrected regulated load signal which compensates for digitalization errors produced by the synchronizer. In one embodiment, the correction loop includes an integrator circuit for superposing on the regulated load signal an inverted integrated error voltage the magnitude of which is a function of the operation of the synchronizer relative to the mark signals. In a second embodiment, the correction loop includes an integrator circuit that periodically applies to the regulated load signal a constant reference voltage of opposite polarity. Preferably, the reference voltage is applied simultaneously with the periods of supply of the compensation current.

Abstract: The corrected values to compensate for errors in instrumental levelling of a theodolite and similar instruments are found by determining angles of elevation and/or horizontal directions, measuring the instrumental levelling errors, and calculating the error free values of the instrument.