REPORT FOR ANALYTICAL CHEMISTS IX. Analog Circuits. Philbrick operational amplifiers illustrate the many applications of operational amplifiers in electrical measurement and control. T h e d.c. level of the operational amplifier is stabilized with a chopper amplifier u s ing t h e a.c. amplifier built in experiment IV. T h e stabilized operational amplifier is used to add voltages, integrate a voltage with r e -
spect to time, a n d provide a constant current. Other applications are pointed out. X. Wave Shaping. T h e effect of resistance-capacitance circuits on various wave shapes is determined. In addition, diode circuits are used to perform the functions of clipping and clamping. XI. Binary Circuits. T h e wave forms a t various points in a bistable
binary circuit are observed. A transistor astable multivibrator is wired and its characteristics are determined. A monostable multivibrator is wired and used to control the gated sweep circuit which was wired in experiment V. X I I - X V . Projects. Four labor a t o r y periods are spent on special projects of t h e student's choice. I n some cases useful components such as pulse or sweep generators or decade counters are built, using soldered connections a n d permanent construction. I t is hoped t h a t as more a n d more electronic components are constructed and more optical and mechanical components become available, it will be possible to p u t together rather complex chemical instruments during this phase of the course. T h e experience of putting together a combination of circuits which have not been pretested proves to be an exciting experience for even our most a d vanced students.
Evaluation and Summary
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ANALYTICAL CHEMISTRY
Our students in the regular semester course tell us t h a t they have gained a working ability and understanding of circuits t h a t help them considerably in their research. Success of the 3-week summer course is probably best indicated by the inquiries already received asking about next summer's course— even though the course has not y e t been announced. One research director recently wrote t h a t his organization was so impressed with the benefits received b y its m a n t h a t it would like to send one or two more men to the course next summer. Reports from other companies with participants last summer have been equally compliment a r y and encouraging. We feel t h a t we have a sound and effective system for presenting electronics and instrumentation to chemists. W e know there are still some bugs in the course, b u t we are now building on a firm foundation. We see dozens of ways of improving reading material, experiments, and components used to construct more complex a n d interesting chemical instruments for the projects.
