In the last 30 days

• Open/close The Control of Humidity by Saturated Salt Solutions

  F E M O'Brien 1948 J. Sci. Instrum. 25 73 Tag this article

  Article References Full text PDF (258 KB)

  A table of data gives percentage relative humidities over saturated solutions of eighty-eight different salts or salt mixtures. Remarks on the suitability of these solutions for humidity control are included.

• Open/close Modified Sawyer and Tower circuit for the investigation of ferroelectric samples

  J K Sinha 1965 J. Sci. Instrum. 42 696 Tag this article

  Article References Full text PDF (333 KB)

  A modification to the Sawyer and Tower circuit is proposed which removes two of the major drawbacks inherent in the original, namely the introduction of phase differences between the voltages on the X and Y plates of the oscilloscope arising because of the different circuit components used in the two branches and also because of the finite conductivity of the sample under investigation.

• Open/close An apparatus for growing single crystals of gallium arsenide

  J L Richards 1957 J. Sci. Instrum. 34 289 Tag this article

  Article References Full text PDF (262 KB)

• Open/close Dry nitrogen gas: simple laboratory production

  J H Robertson 1963 J. Sci. Instrum. 40 506 Tag this article

  Article References Full text PDF (171 KB)

  Nitrogen gas of essentially zero water content can be prepared very simply by electrically controlled boiling of liquid nitrogen. Particulars of the apparatus and its functioning are given.

• Open/close Nuclear resonance absorption circuit

  F N H Robinson 1959 J. Sci. Instrum. 36 481 Tag this article

  Article References Full text PDF (712 KB)

  The new circuit described in Part 1 has the sensitivity and flexibility of conventional circuits using a separate oscillator, combined with the convenience and freedom from microphonics of marginal oscillator circuits. In particular, it permits the use of very low levels of oscillation.

  Because the factors governing the sensitivity of conventional circuits are not widely known, this first paper is largely devoted to their delineation. Only the principles and theory of the new circuit are given in Part 1. Practical design details are relegated to the second paper.

• Open/close Construction and operation of a simple flame-ionization detector for gas chromatography

  D J Morgan 1961 J. Sci. Instrum. 38 501 Tag this article

  Article References Full text PDF (274 KB)

  The construction of a cheap and simple gas chromatograph incorporating a flame-ionization detector is described.

• Open/close Phase-Contrast Microscopy

  C R Burch and J P P Stock 1942 J. Sci. Instrum. 19 71 Tag this article

  Article References Full text PDF (632 KB)

  Slight optical non-homogeneities in certain transparent specimens are usually rendered visible by putting the specimen out of focus. One then sees not the non-homogeneities themselves, but the focal spots and lines they produce. Zernike's method of phase-contrast illumination, on the other hand, provides the maximum contrast when the specimen is accurately in focus, so that what is seen bears a closer resemblance to what is "really there". A simple method of adapting an ordinary microscope for phase-contrast is described, together with the preparation of a test-slide to check its performance. The method has proved helpful in studies of the interaction between leucocytes and mobile organisms.

• Open/close A thermionic trigger

  Otto H Schmitt 1938 J. Sci. Instrum. 15 24 Tag this article

  Article References Full text PDF (220 KB)

  A simple hard valve circuit is described which provides positive off-on control with any desired differential from 0.1 V. to 20 V. Less than 10 ^-6 amp. is required at the input, but up to 20 ma. at 200 V. is available in the output. Either positive or negative control is possible. The operation cycle occupies about 10 μ sec. Applications to cathode ray oscillography, to "thermostating" and to lighting control are illustrated.