Electronic Frequency Meter Research Articles

Metodo a variazione di frequenza per la misurazione della suscettività magnetica delle rocce

method is described for the measurement of the isotropicand anisotropic susceptibility of rocks in a weak alternating field(0,5 Oe; frequency 500 c/sec), based on the frequency variation of an oscillatorin whose inductor the specimen is placed; the frequency variation ismeasured by means of an electronic frequency meter.

Quartz thermometer with a field-effect transistor oscillator

A very simple quartz thermometer is described which consists of a quartz temperature probe with practically linear temperature-frequency characteristic, an oscillator system and an electronic frequency meter. The thermometer measures temperatures from 233 to 373 K with an error < 0.02 K.

On an investigation of slow frequency fluctuations

The possibilities of an experimental investigation of the frequency fluctuations of the oscillations are considered by means of a digital electronic frequency meter. A comparison is made of the results of the measurements with the spectrum of the fluctuations, and an analysis of the errors of the measurements is likewise carried out.

A Direct-Reading Frequency Meter for the Audio and Supersonic Ranges

This paper describes an electronic frequency meter capable of operating in the range from 20 c.p.s. to 200 kc. The reading of the instrument is independent of wave form as long as the input wave does not cross the zero axis more than twice in its fundamental period. For sinusoidal input, the voltage required for reliable operation is less than 0.03 volt r.m.s. between the frequencies of 900 c.p.s. and 200 kc. The sensitivity in the range below 900 c.p.s. can be readily increased by minor changes in amplifier coupling networks. Over a six-month period, the experimental model has shown no change of calibration.

An Electronic Frequency Meter and Speed Regulator

AN electronic frequency meter and speed regulator has been developed to measure and hold the speed of a small steam turbine within plus or minus one-half of one per cent of any speed between 10,000 and 100,000 rpm.

Transactions section: Preprint of corresponding pages from the current annual AIEE transactions volume: An electronic frequency meter and speed regulator

AN electronic frequency meter and speed regulator has been developed to measure and hold the speed of a small steam turbine within plus or minus one-half of one per cent of any speed between 10,000 and 100,000 rpm.

An electronic frequency meter and speed regulator

An electronic frequency meter and speed regulator

A thyratron inflexion indicator for teaching the deaf

In an instrument designed for making pitch variations visible, sound impulses are fed to an electronic frequency meter the output of which is directly proportional to the fundamental frequency. The amplified voltage is applied to the grids of seven thyratrons, which are biassed by successively greater amounts. The number of thyratrons which fire at any given signal therefore depends on the frequency of the signal. The firing of each thyratron lights a neon lamp in its plate circuit, and since these lamps are arranged in a vertical column, the effect obtained is of a column of light which rises and falls with rising and falling pitch. The device presents visually the concept of pitch change and greatly facilitates instruction in voice control.

Recording Instruments for Frequency and Intensity

An inexpensive recorder which employs a spark to puncture a moving strip of chart paper has been constructed. One of the sparking electrodes is a light pointer attached to a short-period D'Arsonval galvanometer element. The other is a curved metal guide which bends the chart paper to the arc described by the tip of the pointer. In conjunction with the logarithmic vacuum-tube voltmeter already described (Rev. Sci. Inst. 4, 672, 1933) this instrument comprises a level recorder having a uniform decibel scale (60 db) and capable of following sound decay curves as steep as 150 db/sec. A new electronic frequency meter has been developed which is capable of following rapid variations of frequency. This device employs gas-filled discharge tubes and yields an output that is strictly linear with frequency from zero to 8000 cycles and independent of the input intensity over a range of at least 35 db. The instrument is flexible and any portion of the frequency range may be fitted to the indicating instrument permitting high sensitivity to small frequency changes. In combination with the spark recorder, or any other type of recorder, this instrument places the delineation of time variations of frequency on an equal footing with time variations of intensity. For example, the melodic curves or intonation of speech and music, vibrato, and attack may be recorded directly.