Index of content:
Volume 17, Issue 5, May 1946
17(1946); http://dx.doi.org/10.1063/1.1770461View Description Hide Description
A trigger circuit using two pentodes with direct plate‐to‐screen coupling is described. The mechanism of electrical stability and instability and the process of triggering are discussed. Sample diagrams for a pulse generator, an electronic switch, and a scaling circuit are given.
17(1946); http://dx.doi.org/10.1063/1.1770462View Description Hide Description
A direct‐coupled pentode trigger pair, previously described, is made the basis of two simple ring‐of‐ten circuits for high speed counting. One of the circuits is especially suited for the counting of sharp pulses up to a frequency of 105 cycles per second. The other circuit is especially suited for frequency measurements on periodic currents of arbitrary wave form and of frequency from zero to above 105 cycles per second. The number of pulses or cycles counted by one ring‐of‐ten is indicated on the screen of a cathode‐ray oscilloscope tube. Several of these ring‐of‐ten units, each with its cathode‐ray tube, can be connected in cascade to make electronic counting with direct indication of the decimal figures possible.
17(1946); http://dx.doi.org/10.1063/1.1770463View Description Hide Description
This attachment extends the range of the GR 760A sound analyzer to one megacycle by means of an oscillator and a tuned mixer which beat high frequency signals down to a frequency accepted by the analyzer. The apparatus is easily constructed, simple to operate, and has proved to be both reliable and flexible. This article describes the circuits and physical arrangements, and discusses the calibration and use of the attachment in the study of high frequency noise spectra.
17(1946); http://dx.doi.org/10.1063/1.1770464View Description Hide Description
The electronic amplifier, described herein, is designed to measure extremely small d.c. and low frequency a.c. voltages in low impedance sources. Expressing the electrical noise in terms of equivalent input voltage with a 5‐ohm input resistance and a 5‐milliamp. Esterline‐Angus recorder, the maximum departure from the mean does not exceed 1.5×10−9 volt. Under laboratory conditions the drift is less than 5×10−9 volt over a period of 8 hours. The amplifier is compact and rugged, and it is not affected by vibrations or accelerations experienced in moving vehicles. At present the amplifier is employed in the measurement of radiant energies in infra‐red spectrographs. It is also used for various laboratory and field measurements.
- LABORATORY AND SHOP NOTES
17(1946); http://dx.doi.org/10.1063/1.1770466View Description Hide Description