摘要:

A new form of apparatus has been developed by the use of which it is now possible to synthesize musical and other sounds from their elemental components. The basic unit in this equipment is an electrostatic alternator. The new device, which is useful in the study of problems in the field of musical acoustics, has been named a ``synthephone.''

ISSN:0034-6748    

DOI:10.1063/1.1751454

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

An air valve designed for the purpose of triggering the expansion of a pneumatic cloud chamber utilizes Bridgman's ``unsupported area'' seal. The valve is controlled by a magnet constructed from the field coil of an inexpensive dynamic loudspeaker. This design allows vacuum tube control of forces up to 75 pounds. High speed of operation (∼1/300 second) recommends its use with counter control, and its extreme simplicity is advantageous in general work.

ISSN:0034-6748    

DOI:10.1063/1.1751455

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

A simple circuit employing neon‐filled cold cathode thyratrons is described for use in controlling cloud chambers. The circuit operates on the standard d.c. line and performs reproducible cycles with great precision and extreme ease of adjustment of time intervals between successive steps of the cycle.

ISSN:0034-6748    

DOI:10.1063/1.1751456

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

The fundamental theory of coupled circuits with distributed constants is reviewed and applied to the problem of designing an oscillator for use in parallel line measurements. An oscillator having a continuously variable frequency range from 75 to 500 megacycles, and which fulfills the theoretical requirements which permit the e.m.f. induced by it in a parallel line to be represented by point generators, is described. Its frequency characteristic is displayed, and its application to parallel line measurements is discussed briefly.

ISSN:0034-6748    

DOI:10.1063/1.1751457

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

We describe an improved counting rate meter circuit, whose output meter reads directly the average rate of appearance of pulses in a counter exposed to radioactive substances. Four output scales are provided on a 100‐microampere meter, such that full scale corresponds to 7200, 2200, 1450, and 400 counts per minute. Even on the highest speed range, the output current is closely proportional to the counting rate over the entire scale. For very low counting rates, an optional register output is provided.

ISSN:0034-6748    

DOI:10.1063/1.1751458

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

A circuit, using a single tube, and having an output voltage which is proportional to the logarithm of a direct current input, is described. The input current range extends from less than 10−7ampere to 10−5ampere if a closely linear logarithmic relationship is desired; and from 10−8to 10−3ampere if only an approximately logarithmic characteristic is necessary. Because the circuit depends for its operation on a fundamental physical law (the Maxwellian distribution of velocities of the thermoelectrons emitted from a hot cathode), its characteristics are constant and predictable.

ISSN:0034-6748    

DOI:10.1063/1.1751459

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

We describe a multi‐staged thermionic amplifier, using two discharge counters, and having an output meter which reads directly the ratio of the activity of two radioactive sources. Continuous photographic recording of this ratio for two fractions of a rapidly decaying source therefore provides a direct observation of their relative activity which is invariant with time, even though a mixture of substances having a variety of half‐periods is involved. The amplifier holds advantages of greater convenience and higher statistical accuracy over the usual single counter amplifier when dealing with sources having moderate strength and half‐periods near the range of five minutes to one hour. It is particularly suited to experiments in which such radioactive substances are used as chemical or biological indicators. A portion of the circuit, consisting of three thermionic tubes, has general applicability wherever direct observations are wanted of the ratio of two d.c. currents.

ISSN:0034-6748    

DOI:10.1063/1.1751460

出版商:AIP    

年代:1939

数据来源: AIP

摘要:

A stroboscopic method discussed by Ba¨r for using a sound wave as a light shutter and viewing the same wave train with the modulated light is modified so as to permit observations to be made with a very simple optical system without lenses. This results in a method of measuring relative or absolute acoustic wave‐lengths in liquids with a precision limited only by that of measuring lengths of the order of a meter and the spacing of lines on a photographic plate.

ISSN:0034-6748    

DOI:10.1063/1.1751461

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751462

出版商:AIP    

年代:1939

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1751463

出版商:AIP    

年代:1939

数据来源: AIP