Digital/analogic converter boards

Analog/digital converter boards can be very useful to incorporate instruments having no communication channel but allowing data to be obtained from their recorder outputs. This facilitates the use of obsolete laboratory instruments. Their greatest weakness is that communication is one-way (from the instrument to the computer, so the former cannot be controlled by the latter). 

Figure 13-24 shows a photograph of a miniature fiber-optic spectrometer using a linear CCD array. The optical diagram is similar to that shown in Figure 13-14, except that fiber optics are used to transport the radiation to and from the sample cell. In the version shown, the spectrometer is external to the computer. The output of the array connects to an analog-to-digital converter board in the computer. In other models, the spectrometer contains the converter and interfaces to the computer via a USB port. Such spectrometers are available from about 1800 to about 5000. 

To have the PSC under real time control of the algorithm, a computer controlled measurement system must be used. The one employed by Young consisted of an S-100 based data logging system with twelve bit analog-to-digital and digital-to-analog converter boards a power... 

The electrical potential of the reaction mixture is measured with a platinum electrode and a Hg/Hg2S04 reference (available from Rainin). The output can be recorded on a single-channel strip chart recorder, with the platinum electrode attached to the positive terminal and the reference to the negative, or the recording can be made via a high-impedance input to an A/D board (analog-to-digital converter) on a computer (see Chapter 3). 

At first, various reactor experiments were reviewed to identify signal type, dynamic range, number of channels, etc., and then ccmmercial I/O boards were surveyed to choose proper one. So far, the effort has been concentrated on the use of PC counter because its application is not so popular in general compared to the use of analog to digital converter (ADC) while it shares very important parts in the research reactor experiments especially for a new reactor coninissioning. As an ADC board has few counter channels, however, a pure counter board which can accept up to nine pulse channels, should be self designed. 

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