Active circuits

In modern systems, the applied electric power is increased over time to compensate for the decreasing intensity. However, this adjustment uses the average degradation curve of a lamp as a reference, not the actual values of the lamps mounted in a particular sunbed. A radiation sensor could be used to control an active circuit that regulates the intensity of radiation. 

Figure 24. Integrated active-substrate system proposed by Stanford University. The system includes cantilever bonding, microcapillary die attachment, and microchannel heat exchange on a silicon substrate with active circuits. (Figure was based on reference 167.)...

Fast detection of the electro-acoustic impedance is a condition for successful kinetic studies. Soares [64] introduced a circuit to measure both resonant frequency and damping resistance R, though not as fast as simple active oscillator methods mainly used for resonant frequency measurement. Most active circuits operate in the series frequency a>s although some oscillators are designed to operate in the parallel frequency wp , which is slightly higher and very susceptible to the value of Ca. 

The solution conductivity was measured using a Yellow Springs Instrument conductivity meter (YSI Model 34) with a high pressure conductivity cell (cell constant of 0.0044 cm ). The high pressure cell consisted of ten stacked, stainless steel disc electrodes (10-mm diameter discs), insulated with Teflon washers. The meter is particularly well suited for use with this type of cell because capacitance errors are minimized by the active circuit and electrode over-potential is eliminated by measurement potentials of less than 1 volt. 

Active Circuit Elements. High-Gain DC Amplifiers... 

The two other important active circuit elements, function generators and function multiplier-dividers, require a somewhat lengthy and special treatment and will not be considered here. The interested reader... 

Phase shifters range from simple delay lines to mechanically or electronically controlled delay lines to those based on phase locked loops or other active circuits. Quadrature and 180° hybrids as well as DBM s can be used as fixed value broadband phase shifters. This last point is important since most continuously adjustable phase shifters are frequency dependent. Phase shifters in NMR spectrometers are required to set the reference phase in a phase sensitive detector and also to set the relative phases of rf pulses as required for various pulse sequences. 

Figure 3.7 Schematic diagram of a phase-sensitive detector at 20 MHz. The transformer is replaced by an active circuit in the HP8709A synchroniser, and probably most high precision configurations. The phase error voltage output is amplified and used in the spectrometer to control the YIG oscillator magnetic field and hence lock the YIG source frequency to the synthesiser frequency. An identical device locks the Gunn MMW source to the YIG frequency (Adapted from Connor )...

Targets are defined based on the best operating plant values and they should assume circuit activity, circuit leak rate, etc. 

Usually the impedance is measured as a ftmction of the frequency, and its variation is characteristic of the electrical circuit (where the circuit consists of passive and active circuit elements). An electrochemical cell can be described by an equivalent circuit. Under appropriate conditions, i.e., at well-selected cell geometry, working and auxihary electrodes, etc., the impedance response will be related to the properties of the working electrode and the solution (ohmic) resistance. 

Switching. Electrolyzers must be switched out of an active circuit before disassembly or removal from their berths. After repair or replacement, they must be physically reconnected and then switched back into service. 

Fig. 3. Closed active circuit (a) and its transformation into a tree (b). 1-4(4, 4"), 5(5, 5") -numbers of nodes arrow in the circle - source of the motive pressure arrows - specified directions of flows in branches.

Equation (39) makes it possible to determine the objective function of MEIS and correspondingly the objective extremality criterion for stationary isothermal flow distribution of incompressible fluid in a closed active circuit. Account will be taken of the fact that because of equilibrium point stationarity the integrals corresponding to both sums in (39) take equal extreme values. For further analysis it is more convenient to make use of the latter and MEIS can be written in the form ... 

The physical phenomena of resonance is due to an exchange of energy between electric and magnetic fields. In passive RLC circuits, the energy can be stored in the electrical field of a capacitor and transferred to the magnetic field of an inductor, and vice versa. In an active circuit, such as an op-amp bandpass filter with no inductors, energy can be exchanged between capacitors. 

The ideal op-amp is an abstraction that is useful in the design and analysis of active circuits. A design can be formulated in terms of ideal op-amps, and later, if the design shows promise, the circuit can be analyzed in more detail to make sure it works in all circum-... 

Bruton, L.T. 1980. RC-Active Circuits. Prentice-Hall, Englewood CHffs, NJ. 

In Eq. (7.188a), V[n has been multiplied by a constant K so that the active circuit can realize the required transfer function with an arbitrary gain factor. 

FIGURE 7.127 (a) Passive ladder network with grounded inductors, (b) active circuit simulation of (a). Copyright 2005 by Taylor Francis Group... 

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