Resistor load

Eigure 11 shows a schematic and collector characteristics for a common emitter n—p—n transistor circuit. The load line crossing these characteristics shows the allowed operation of the transistor with a supply voltage, = 12 V a load resistor, 7 = 2 and a bias resistor, 7 g = 20 kQ. The load line corresponds to the equation = 7 7 -H. Plotting the load line on the collector characteristics defines BJT behavior 0.6 V is required... 

Fig. 10.15. Example of preamplifier with cold input stage. RB = bolometer load resistor, / heat = cold...

Once the electrons have been accelerated and multiplied, they reach the anode. The electrons arriving at the anode produce an electrical current. This current can be measured directly, or indirectly by monitoring the voltage increment induced in a given load resistor, Rl. This load resistor is critical, as it determines the time constant of the photomultiplier. A typical time constant for a photomultiplier is 2 ns, although an adequate choice of the load resistor and anode material could lead to time constants as low as 0.5 ns. 

Because the response time of the detector depends on the thermal time constant of the detector element / electrode assembly, coupled with the electrical time constant of the device capacitance and load resistor - the response versus modulation frequency (f shows a typical l//m form. 

In practice, neither the absolute energies nor their ratio is determined directly. Instead, the radiation of a particular wavelength falls on a multiplier-type phototube, and the voltage developed across its load resistor is measured with.a cathode-ray oscillograph. The deflection to the oscillograph is then proportional to E ... 

Figure 18 Stability test carried out with two sealed DSSCs over 7000 hr of continuous illumination with visible light (polycarbonate 395-nm cutoff filter) at 1000 W/m2 light intensity. The photocurrent and voltage drop measured across an external load resistor of 10 ft are plotted as a function of irradiation time. Cell 1 (solid line) was continuously illuminated at 35°C the same for cell 2 (broken line) except that it was operated for a 700-hr period at 75°C and for 1000 hr at an open circuit. (From Ref. 153.)...

The current pulses pass through the load resistor R, and the resulting voltage is displayed on an oscilloscope and then photographically recorded. The load resistor is adjusted so that the RC time of the resistor-cable-oscilloscope combination is much less than the time constant of the fluorescent decay. 

Fig. 2.1 Basic electrochemical cell. Interconnection of the two electrodes through the external load resistor allows the spontaneous cell reaction io proceed...

For spontaneous discharge, the overall cell voltage must be reduced from its equilibrium value, as would happen if a load resistor were connected to the terminals. If a potential difference greater than the emf were applied (i.e. one making the cathode more positive and the anode more negative), the net result would be a current flow in the reverse direction, causing a net charging of the cell. 

It can be shown from Figure 11 and Equation 1 that the rise time of the signal will be controlled by the RC time constant of the circuit loading the pyroelectric current generator. The simplest case is where the heat flow into the pyroelectric is one dimensional as shown in Figure 12. Then the signal across the parallel load resistor of the pyroelect-ic element is... 

Where Rl is the load resistor connected with the drain electrode, gm the transconductance of the FET, and the capacitance of the gate insulator. It has been shown experimentally that V0ut is linearly dependent upon relative humidity in the almost whole humidity range. 

If a load resistor Rl is connected across the Zr02 electrochemical cell of Fig.l, a current will continuously pass through the closed circuit given by... 

Figure 4.20 Equivalent circuit for the channeltron/channelplate as the current source i(t) shown together with the main components of the external circuit. CD is the capacitance of the detector which is depicted by the dotted lines in order to indicate that - in contrast to actual electronic components - it is a property inherent to the detector HV is a high voltage source, Ra the load resistor, CK the high voltage coupling capacitor and Amp the...

FIGURE 6.9 Typical wiring of a photomultiplier. Each of the dynodes, beginning in the photocathode, is linked stepwise by resistors RD of the same value. The photocurrent is read as the voltage drop across the load resistor R with high impedance filter (Rf, Cp) and oscilloscope or transient digitizer (detector). 

In addition to the sensitivity of the detector, the other concern is how fast it responds to a change in the intensity of light. Equation 6.53 gives the voltage drop Vt t) on the load resistor R that will be fed to the SH and digitizer (Figure 6.10). 

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