Semi-integration in practice

Two approaches have been used to semi-integrate electrochemical currents analog [43, 82—84] and digital [55, 60, 85]. Each has been used satisfactorily in experimental voltammetry. We discuss analog methods first. 

In order to appreciate the principles of analog semi-integration, let us first review the classical operational amplifier circuits shown in Fig. 30. The output of circuit (a) is a voltage proportional to the instantaneous value of the current input 

In eqn. (160), we write the unusual operator notation d-1/df-1 for indefinite integration to emphasize the analogy with semi-integration. When the feedback loop of the operational amplifier contains a resistor, 

The related circuit, shown in Fig. 35, performs semi-differentiation 

Turning now to digital methods of semi-integration, we shall describe a technique by which the semi-integral m may be determined from a set of equally spaced current values, i 0, ii, i2,. . . , . . . , . If A is the time 

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