Amplifier characteristics

An example of the realization of such impedance by a thin-walled fibreglass tube for a sink at 4.2 K is shown in Fig. 10.16. The overall amplifier characteristics are reported in Table 10.1. 

In all the numerical examples illustrated thus far, the potential changes across the interface were primarily governed by xu rather than by amplifier characteristics. Under these conditions, it is a simple matter to calculate the current due to double-layer charging if Ru and Cdl are known or can be estimated. The peak value of this current is equal to the change in potential divided by Ru and it decays exponentially thereafter. Following a given number of time constants, the contribution of the charging current to the total current measured can be determined and thereby the extent of error in the quantity of interest, the faradaic current, can be estimated. 

The design of amplifiers and the function of their components are beyond the scope of the text. Interested readers may consult the references at the end of this chapter. Here we picture the amplifier simply as a black box (Fig. 3.28) and discuss only those amplifier characteristics conceptually important for analog computer solutions. Designating the input and output potentials relative to the ground by and eo, respectively, we first define the gain A of the of amplifier by the ratio15... 

In order to avoid the use of the telescope and scale, which do not lend themselves to convenient use either for classroom demonstrations or for routine titration work, it occurred to the writer to make use of the amplifying characteristics of the vacuum tube to magnify the currents to such a value that they could be easily measured with a portable milliammeter. 

Irvine, R.G. 1994. Operational Amplifiers Characteristics and Applications, 3rd ed. Prentice-HaU, Englewood Cliffs, NJ. 

It has been demonstrated that PVDF based membrane hydrophones have negligible degradation in sensitivity with time, as well as good temperature stability and manufacturing reproducibility [10]. Also, a comprehensive model of the membrane hydrophone sensitivity transfer function has been developed [11]. This model incorporates multiple PVDF layers and amplifier characteristics, as well as the electrical cable and load. 

In summary, the amplitude of the interferogram as observed after detection and amplification is proportional not only to the intensity of the source but also to the beamsplitter efficiency, detector response, and amplifier characteristics. Of these factors, only 7(vo) varies from one measurement to the next for a given system configuration, while all the other factors remain constant. Therefore, Eq. 2.4 may be modified by a single wavenumber-dependent correction factor, 7/(vo), so that the ac signal, 5(8) (in volts), from the amplifier is... 

For an industrial application it is necessary to separate the response of a real crack from artifacts, and to derive information about the geometry and the location of the crack. For this purpose we have developed a filter which is sensitive to the characteristic features of a signal caused by a crack and amplifies it, whereas signals without these typical features are suppressed. In Fig. 5.1 first results obtained with such an iterative filter algorithm are shown. 

Gadolinium ethyl sulfate has extremely low noise characteristics and may find use in duplicating the performance of amplifiers, such as the maser. 

The stiffness characteristic of the positioner/actuator varies with frequency. Figure 8-75Z indicates the stiffness of the positioner/actu-ator is high at low frequencies and is directly related to the locked-stem pressure gain provided by the positioner. As frequency increases, a dip in the stiffness curve results Trom dynamic gain attenuation in the pneumatic amplifiers in the positioner. The value at the bottom of the dip is the sum of the mechanical stiffness of the spring in the actu-... 

Floor acceleration This is the time history of acceleration of a partictilar floor nr structure caused by a given ground acceleration (Figure 14.16). It may have an amplified narrow band spectrum due to structural filtration, where single frequency excitation and resonance may predominate, depending upon the dynamic characteristics of the structure. A floor response spectrum (FR.S). as shown in Figure 14.18, can be derived from this history. Consideration of GRS or FRS will depend upon the location of the object under test. 

If the shafts are too far apart, the teeth mesh above the pitch line, which increases the clearance between teeth and amplifies the energy of the actual gear-mesh frequency and all of its sidebands. In addition, the load-bearing characteristics of the gear teeth are greatly reduced. Since the force is focused on the tip of each tooth where there is less cross-section, the stress in each tooth is greatly increased. The potential for tooth failure increases in direct proportion to the amount of excess clearance between the shafts. 

The tube of Figure 2-2 can be operated as an ionization chamber, as a proportional counter, or as a Geiger counter. The tube output differs radically from one case to another. Because of these differences, the electronic circuitry associated with the tube must also be different for each case if the pulses from the tube are to be reliably selected and counted. In particular, the circuitry will have to differ in characteristics such as stability, amount of amplification, and time of response. In all cases, linear amplification (amplifier output always proportional to tube output) is desirable. 

Scintillation counters also have a characteristic plateau. In the scintillation counter the phototube acts as the primary amplifier with a gain as high as 106. A low-gain linear amplifier may be used in conjunction with a scintillation counter, and, again, the range of amplification in the plateau will be about 103 or 104. 

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