Utilization of Recent Electronic Devices in Electrochemical Laboratory

Abstract

The use of recent electronic devices such as linear IC (especially operational amplifiers), digital IC and various modules used to interface, are described for electrochemical applications. Those devices are treated as a ‘black box’, so that most chemists can use them as functional elements to construct various systems with no consideration of their inner principles. The present paper is divided into two parts ; the first half deals with analogue electronics and the second half with digital electronics. Analogue electronics is arranged in the following sections : 1) Analogue electronics as control elements. The basic principle of an operational amplifier is illustrated and then as an example of control use, a new electrolysis which is more general than usual chronopotentiometry or chronoamperometry is described, where the electrode potential and the current is controlled simultaneously. 2) Linear processing of analogue signals. Several simulation techniques are cited and criticized from a view point of laboratory use. CSDT (continuous space and discrete time) method and transfer function method are recommended as the simulation techniques for electrode processes. 3) Non-linear processing of analogue signals. An irreversible electode process including non-linear elements as exponential terms is cited and its simulator is given. 4) Analog switch. The principle of analogue switch is illustrated and application of it such as switching correlator and signal modulator are described. In last section of analogue electronics, promising devices such as phase-locked loop amplifier and photo-coupler as an isolator are described briefly. In digital electronics part, the importance of the knowledge for hardware is emphasized and several reasons for digitalization in measurements are interpreted. Then, the fundamentals of digital electronics are outlined briefly, assuming no previous knowledge of electronics. The operation of RS-flip-flow is given onsiderable space for understanding of the higher devices such as counters and shiftregisters. After fundamentals, digital electronics for polarographic applications are described as follows : 1) Long-period integrator for coulombmeter. The combination of V-f converter and counter is recommended as a digital coulombmeter in electrochemistry. 2) Signal generator. The use of digital IC as a signal generator is illustrated. Astable mutivibrator and monostable multivibrator are illustrated. Double-pulse generator is cited as the typical example of electrochemical use. Maximum-period signal generator is introduced as a pseudorandom signal generator. 3) Digital memory. Digital memory device for transient recording is illustrated. The device was constructed from ADC (10bit resolution and successive approximation type), DAC (10bit), MOS dynamic shift registers (10×1024 bit) and some gates for read/write control. The device was applied to electrochemical system to facilitate the correlation techniques. Typical results are illustrated. Possible use of the device is discussed. 4) Microcomputer. The use of one-chip c.p.u. for microcomputer organization isdiscussed. The possible construction of microprocesser in laboratory is described.