Analog output

On the output side, dedicated digital-to-analog converters are provided for each analog output. Outputs are normally unipolar, and require a lower resolution than inputs. A 10-bit resolution is normally sufficient, giving a resolution of 1 part in 1000 or 0.1%. 

Example 5.7 We have to design a servo-controller for a mixing system. A blue dye for making denim is injected into a stream of water. The injected dye is blended into the pipe flow with the aid of in situ static mixers. A photodetector downstream is used to monitor the dye concentration. The analog output of the detector is... 

Analog output, optional potentiometric, voltage or current ... 

Chromatographic System. The isocratic liquid chromatograph used was a Waters Associates (Milford, MA) Model 24A alc which included a Model 6000A Solvent Delivery System, a Model 401 Differential Refractometer and a Model 440 Absorbance Detector operating at 254 nm and was fitted with a WISP automatic injector. The analog outputs of the UV absorbance detector or differential refractometer were recorded with a Model 730 Data Module (printer, plotter, integrator)(Waters). Eluent flow rate was 1.0 ml/min unless otherwise noted. 

Unless technically impossible, accuracy and linearity of each output chain are checked. Visualization of values sent to the equipment is made either directly on the checked peripheral system or using appropriate equipment. Accuracy of values transmitted from the analog outputs is checked by using an appropriate calibrated reference instrumentation traceable to national official standards. 

The rate meter provides the required high voltage for (he photomultiplier iibes and converts the digital signal obtained from the scintillation crystal to an analog output for the recorder. 

For the chromatographer who has several (more than four) chromatographs with analog output, multichannel minicomputer-based systems are available from several manufacturers. For the most part, these systems use a minicomputer that is dedicated to the task of data acquisition, data reduction, and reporting of results for a number of chromatographs. Typically, the programs... 

A/D conversion is of increasing importance as, in many instances, the analog outputs of various measuring elements are now frequently connected to microcom-... 

A DSP system begins at the conversion from the analog input and ends at the conversion from the output of the processing system to the analog output as shown in the figure... 

Figure 14.1 A/D conversion, (a) Analog output (b) analog signal.

Erincipal advantages of piezoresistive transducers are a much higher ridge voltage output and smaller size. Full-scale output voltages of 50 to 100 mV/V of excitation are typical. Some newer devices provide digital rather than analog output. 

Specific detectors are also available for quantification of radiopharmaceuticals. These detectors use a position-sensitive proportional counter. These detectors are sensitive to the beta and gamma nuclides listed in Table 3.5. The detector analog output can also be represented as an analog curve. Various other detection procedures have also been used, such as flame ionization [66], mass spectrometry [27,67], and infrared (IR) [68,69]. 

Controller output from the secondary PID to an analog output (AO) block... 

Performance Criteria Platinum Element Nickel Element Digital Output Analog Output (4—20 mA DC)... 

One aspect of CAD detection to be aware of is that analyte response is directly proportional to percentage of organic however, the magnitude of this effect is very similar for all compounds.69 Therefore, a shift in retention time will cause a difference in response. Because of the uniformity of response characteristics outlined above, CAD is a very interesting option as a universal detection system for HPLC. From the author s experience, it is a very simple detector to utilize and can be integrated with laboratory data collection system quite easily with the analog output. 

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