2018 Electronic Competition Question A-Current Signal Detection Device (Tianjin)

This set of current signal detection device can amplify the signal generated by the arbitrary waveform signal generator using the LM1875 power amplifier, thereby achieving a voltage peak-to-peak value of 10V through a 10Ω resistance. The current sensor is made of a manganese core magnetic ring and enameled wire, uses the principle of current mutual inductance to obtain the current signal, and converts the current signal into a voltage signal by connecting a resistor. Then a preamplifier is used to amplify it, and then a programmable amplifier is used to amplify it again. The MCU dynamically adjusts the gain of the programmable amplifier according to the voltage peak of the preamplifier circuit, thereby achieving a large range of current measurements. The comparator converts the arbitrary waveform signal into a square The wave signal is input to the MCU for frequency measurement. The ADC collects the voltage waveform in real time and performs FFT operation to obtain the spectrum information of the waveform. Finally, the LCD display is used to display information such as the frequency and peak-to-peak value of the current signal.