Analog oscilloscopes

In the current apparatus, the TOF signal was displayed on a 400-MHz analog oscilloscope. The waveform from the screen was coupled into an IBM personal computer for data analysis and storage. In general, TOF experiments are carried out under single-shot measurements, which means that the single-event bandwidth of the oscilloscope must be much larger than l/t-p. 

The correlation function data are then transformed by a digital analog converter and displayed on an oscilloscope where the evolution of Ci(r) may be conveniently watched. Alternatively, the digital output may be punched on paper tape for subsequent analysis. A typical solution will allow Ci(t) to develop in 5-15 sec with sufficient signal to noise ratio to obtain the time constant with an accuracy of 1% or better. 

The constants A and B may be determined from a display of the spectrum on an oscilloscope, and entered into the computer either by teletypewriter,155 or directly, by digitization of the analog voltages from several potentiometers.160 Automatic phase-correction programs... 

The rapid development of solid-state electronic devices in the last two decades has had a profound effect on measurement capabilities in chemistry and other scientific fields. In this chapter we consider some of the physical aspects of the construction and function of electronic components such as resistors, capacitors, inductors, diodes, and transistors. The integration of these into small operational amplifier circuits is discussed, and various measurement applications are described. The use of these circuit elements in analog-to-digital converters and digital multimeters is emphasized in this chapter, but modern integrated circuits (ICs) have also greatly improved the capabilities of oscilloscopes, frequency counters, and other electronic instruments discussed in Chapter XIX. Finally, the use of potentiometers and bridge circuits, employed in a number of experiments in this text, is covered in the present chapter. 

One application of an analog oscilloscope is in examining the relative phase relationship of two sinusoidal wave forms, one of which (of frequency is supplied to the vertical input (/) of the oscilloscope, the other (of frequency /j/) to the horizontal input (x). When the display mode is chosen to be. v vs. /, the. v voltage replaces the internal sawtooth sweep voltage and the oscilloscope becomes a sensitive device for comparing the frequencies of the sine waves. When the ratio of the frequencies is a rational fraction, a symmetrical closed pattern called a Lissajous figure will appear on the screen. The frequency ratio can be obtained from the form of the pattern by using the formula... 

The intensities of the sample and reference beams are measured with photodiodes by an analog data acquisition card and/or digital oscilloscopes to calculate the absorbance of the sample. The time resolution of the photodiodes is not important for this application but it is essential that their photoresponse is strictly linear to the light pulse intensity. Each absorbance measurement can be corrected for the absorbed radiolytic dose by measuring the charge in the electron bunch using a Faraday cup or some other detector. At each pulse-probe delay, it is necessary to measure the sample absorbance in the presence and absence of the electron beam, the latter measurement serving as the baseline. In practice, since the probe beam transport distances in these facilities may be several meters or more, optical transport fluctuations due to vibration and air turbulence in the 40-100 ms interval between the sample and baseline measurements... 

The voltages u,v,w at three different points in the circuit are proportional to Lorenz s x, y,z. Thus the circuit acts like an analog computer for the Lorenz equations. Oscilloscope traces of u t) vs. w t), for example, confirmed that the circuit was following the familiar Lorenz attractor. Then, by hooking up the circuit to a loudspeaker, Cuomo enabled us to hear the chaos—it sounds like static on the radio. 

STEP 3 Hook up an analog computer according to the block diagram and display the outputs A, B, C, and D vs t on an oscilloscope or xy plotter. 2-16. Solve Prob. 2-15 by analytical integration of the differential equations (dimensionless form). 

The electronic signal obtained from the photodetector is usually electronically amplified, measured using some sort of galvanometer, and presented in either analog or digital form. The signal may alternatively be recorded on a strip-chart recorder, to supply a permanent record of the spectrum. The limitation of these recorders, however, is the relatively long response time of the pen. This limits the speed at which accurate spectra can be obtained. Oscilloscopes have been developed, however, in which elaborate electrical circuits have been employed to obtain spectra with a much shorter response time. 

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