. Electronic apparatus for biological research. Electronic apparatus and appliances; Biology -- Research. 44 DESIGN PROCEDURE The procedure to be described in this chapter is only one of many possible. It is the way the author works, but he anticipates that readers will soon develop their own methods of attack. The steps which lead from the original conception of a new piece of apparatus to its final realization in the metal are illustrated by the use of an example, the production of a complete electrophysiological unit for students' use. We begin with a specification, which may run something
. Electronic apparatus for biological research. Electronic apparatus and appliances; Biology -- Research. 44 DESIGN PROCEDURE The procedure to be described in this chapter is only one of many possible. It is the way the author works, but he anticipates that readers will soon develop their own methods of attack. The steps which lead from the original conception of a new piece of apparatus to its final realization in the metal are illustrated by the use of an example, the production of a complete electrophysiological unit for students' use. We begin with a specification, which may run something like this: Stimulator—two repetition rates, ISJSQC and 1/sec; two shocks to be provided, each with a delay variable up to 30 msecs from the initiation of the time-base sweep. Exact shock waveforms immaterial, but shock- strength adjustable up to a maximum equivalent to a rectangular pulse of 30 V amplitude into 10 kQ and lasting \ msec. Time base—triggered by stimulator, providing trace lengths adjustable from 10 to 80 msec. Switchable 10 msec time-marking pips to be provided so that the trace length may be set up to an exact multiple of 10 msec within the range provided. Pips derived from the 50 cycle mains would be sufficiently accurate. Shock out to preparation. Figure Amplifier—A direct-coupled amplifier of maximum gain such that the cathode ray tube spot is deflected to top or bottom of the screen by ±25 mV: this is for intracellular work. In addition, a pre-amplifier, coupled, of short time constant, gain 100 times, suitable for the detection of weak action potentials. Presentation—6 in. diameter flat-faced cathode ray tube, medium per- sistence ( green) phosphor. Power supplies—As requisite. 671. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Donaldson, Peter Ede
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