Frequency meter - LC measuring instrument

  
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Feature of an offered frequency meter that he besides the main function allows to define inductance of various coils, resonant frequency of contours, capacity of condensers. The combined device which schematic diagram is shown on fig. 1 becomes the good assistant to the radio fan designer. For its manufacturing scarce details are not required, it
Frequency meter - LC measuring instrument - schematic

is simple in adjustment and in operation. The device it is possible to measure frequency of signals by amplitude 0, 1. 5 In sinusoidal or squared in a range from 50 Hz to 500 kHz, and also inductance from 4 ½ to 1 Gn. For convenience of counting of indications the working range of values is broken into four ° ° · ½ °. The first of them establish at frequency measurement to 500 Hz. The second - at frequency measurement from 500 Hz to 5 kHz or inductance from 40 ½ to 1 Gn. The third - at frequency of a signal from 5 to 50 kHz, values of inductance 0, 4. 40 ½. And the fourth poddiapazon-at frequency of a signal from 50 to 500 kHz and values of inductance 4. 400 ½. Necessary ° ° · ½ establish the SA2 switch, and a mode of measurements (frequency or inductance) - SA1. The error of measurement of frequency does not exceed 5 %. The principle of work of a frequency meter is based on transformation of an entrance signal to sequence of rectangular impulses with stable duration and amplitude and the subsequent measurement by the microampermeter of average value of a current of this sequence. Simply work of a frequency meter explain  ‹, given on fig. 3. A studied signal (fig. 3, and) submit on an entrance of buffer knot which is executed on the VT1 transistor. Purpose of knot - to provide big entrance resistance and the minimum entrance capacity of a frequency meter. From a knot exit the signal arrives through the SA1 switch section...



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