Cheap frequency meter by CA3130

  
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This cheap frequency meter circuit that we show to you. Suitable for general use in small laboratories. Because cheap, easy to build. And Qualified enough. For applications most of the electronics amateur. It can be shown that the frequency read directly from the meter. Can measure the frequency of 100 Hz (full scale) to 100KHz (full scale). By the characteristics of the waves do not affect the accuracy of the circuit.
Cheap frequency meter by CA3130 - schematic

Even low levels, can be measured to a hundred millivolts. (100mV) The working principle of the cheap frequency meter is simple. Internal its there is a generates narrow pulses circuit up. By same frequency as the signal to be measured. These pulses will go to make a meter needle swing more or less. By an average of caused by current pulses. Which the average value will be ratio with amount of pulses that occur in a time period. The signal that is measured has a low frequency and amount of pulse will be few. The current average flow meter is less. But if the signal that is measure has high frequency, number of pulse too much will has the high average current makes the meter needle swing up. So, We can set the width of each pulse constant, then The swing of the meter needle is in proportion to the frequency of signal that is measured there. We so adjust the scale of meter to read value as frequency It directly with a linear scale. (each channel of the scale are spaced evenly. ) -In figure 1 is the complete circuit of the cheap frequency meter. This circuit uses two ICs are CA3130 and LM555. The first is a OP-amp Ic is work faster and has the input impedance is very high. This IC is connected as the schmitt trigger circuit to extend the input signal to act up and force you to convert the input signal to a square wave with a fixed height. For the second IC as a timer IC NE555 which is connected as a monostable multivibrator...



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