Instrumentation: analogue digital

In this series of instruments for analytical electrochemistry, Philips also supplies the microprocessor-controlled PW 9527 digital conductivity meter with 16 push-buttons and on the rear an analogue output for connection to a recorder and a 25-way connector providing a two-way RS 232 serial connection (see Philips leaflet 9498 362 9326). 

This technique is of high accuracy and is meant to be used in precision measurement instrumentation, for it is inherently insensitive to the DC-offset and the AC-noise in the sinusoidal signal which can be substantially reduced by a great variety of electronic devices ranging from various electronic analogue filters, and digital filters to the most effective lock-in amplifiers. 

Instruments that can satisfy these criteria can be analogue or digital. We now describe these two types. 

A second factor that can influence quantitation is digital resolution in the intensity direction (or vertical scale in the graph). This is due to the analogue to digital converter (ADC) and sometimes can be experimentally corrected by changing the receiver gain. However, for most modern instrumentation this limitation is not so serious and, therefore, will not be discussed in detail below, but is illustrated in Problem 3.7. 

Cheap and capable digital web-cameras and microscopes. These make possible surveillance of experiments and their display on computer monitors. Simple and intuitive analogue instruments, such as bulb thermometers and bourdon-tube pressure gauges, may also be monitored web cameras. 

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