Instrumentation amplifier precision

As an example of the application of an instrumentation amplifier we consider the bridge circuit shown in Fig. 7.106 (a), which is formed by two 350-S2 strain gauges and two other 350-f2 precision resistors, each... 

Unlike the photoplate, the Faraday detector (or Faraday cup) is still very much in use today. The main reasons for its lasting popularity are accuracy, reliability, and mgged construction. The simplest form of Faraday detector is a metal (conductive) cup that collects charged particles and is electrically connected to an instrument that measures the produced current (Fig. 2.21b). Faraday cups are not particularly sensitive and the signal produced must in most applications be significantly amplified. An important application for Faraday detectors is precise measurements of ratios of stable isotopes [278]. See, for example, Section 2.2.7 and Chapter 11 for examples of applications and methods in which Faraday detectors are utilized. 

This technique is of high accuracy and is meant to be used in precision measurement instrumentation, for it is inherently insensitive to the DC-offset and the AC-noise in the sinusoidal signal which can be substantially reduced by a great variety of electronic devices ranging from various electronic analogue filters, and digital filters to the most effective lock-in amplifiers. 

An XPS spectrometer contains an X-ray source - usually Mg Ka (1253.6 eV) or A1 Ka (1486.3 eV) - and an analyzer which, in most commercial spectrometers, is hemispherical in design. In the entrance tube, the electrons are retarded or accelerated to a value called the pass energy , at which they travel through the hemispherical filter. The lower the pass energy, the smaller the number of electrons that reaches the detector, but the more precisely is their energy determined. Behind the energy filter is the actual detector, which consists of an electron multiplier or a channeltron, which amplifies the incoming photoelectrons to measurable currents. Advanced hemispherical analyzers contain up to five multipliers. For further details of these instruments the interested reader should refer to other textbooks [20, 21]. 

Similarly, when we listen to music through a speaker, what we hear is the original music, distorted by its passage through whatever recording device (microphone + amplifier), storing device (such as tape, casette, record, compact disk), and audio reproduction system (amplifier, speaker) is used. More precisely, what we hear is the convolution of the original music and the instrumental response. 

The two instrumental components which have the most significant effect on the hmit of detection and precision of analysis are the burners and the hollow cathode lamps. For the two instruments used in this study, there was no evidence that other components (monochromator, detector, amplifier, etc.) were limiting factors in the detection limit or precision. 

The most common high precision laboratory instruments are the thermal mass flow meters. (They are among the most expensive and can cost over 2000. ) The principle is based on an energy balance either the entire flow or a slipstream is heated at a constant rate and the temperature rise is recorded. The temperature (or temperature difference) of the fluid is measured and amplified it is proportional to the mass flow rate ... 

Before operational amplifiers became available, constant current coulometry (CCC) was used more often than controlled potential coulometry (CPC) because the instrumentation was so much simpler. CCC continued to be used for highly precise U determinations in very pure materials (Goode et al. 1967 Malinowski 1967 Merciny et al. 1981). 

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