LCR measuring instrument

1. Measurement principle: Input a sinusoidal signal, measure the effective value U of the voltage and the effective value I of the current at both ends of the resistance, capacitance, and inductor, and then calculate the impedance Z, Z=U/I.
Among them, the resistance R=U/I, the capacitance C=1/(2*π*f*Xc), and the inductance L=XL/2*π*f.
 
2. Measurement of resistance, inductance, and capacitance
Measurement of resistance: The impedance of a resistor is equal to the resistance itself, formula: Zr=R=U/I
Measurement of capacitance: The impedance of a capacitor is the capacitive reactance, formula: Zc=Xc=U/ I=1/(2πfC), then C= 1/(2*π*f*(U/I))
Measurement of inductor: The impedance of the inductor is the inductive reactance, formula: ZL=XL=U/I=2πfL , then L= (U/I)/2*π*f 3. Prerequisite for
 
the identification of resistance, inductance, and capacitance : at least two sine waves with different frequencies and the same amplitude are required.
For example: f1=1kHz; f2= 10kHz.
Identify the resistance: Because the resistance impedance is not affected by the frequency, the impedance Z1 at 1kHz and the impedance Z2 at 10kHz are the same size. When Z1=Z2 is measured, it means it is a resistance.
Identify the capacitor: The characteristics of the capacitor are AC and DC. Therefore, the impedance Z1 will be greater than the impedance Z2. When Z1 is measured to be greater than Z2, it means it is a capacitor.
Identify the inductor: The characteristics of the inductor are direct and isolation. Therefore, the impedance Z1 will be smaller than the impedance Z2. When Z1 is measured to be smaller than Z2, it means it is an inductor.
 
4. Video reference link
https://www.bilibili.com/video/BV1MY411b7z7?share_source=copy_web
 
 
5. You can watch the reference video to explain
the circuit principle of the work
. Teacher Tang explains it very well.
 
Schematic design
The schematic is the latest schematic. I made a version and found that the power supply of 8554 was connected reversely. This wrong schematic has been fixed. The PCB in the
 
PCB design project is the first version of the PCB. The power supply of 8554 is reversed and cannot be used directly! When debugging the work, I cut off the wire of the power supply pin of the 8554 chip, jumped two wires, and the circuit became normal. There is a waveform output at the output end. The actual work and the debugging results. The front view and the back view clip a 47k resistor. You can see the oscilloscope waveform, as shown in the figure: Resistor voltage drop Vpp1: 1.12V Resistor current Vpp2: 2.36V voltage effective value calculation: U= Vpp1/magnification/ (2*0.707) = 0.19796V Current effective value calculation: I= Vpp2/amplification factor/(2*0.707)/transimpedance amplifier resistance 100kΩ=0.00000041713 Resistance value calculation: R= U/I = 47457Ω Measurement result analysis: multimeter The measured resistance value was 46.3KΩ, and the measuring instrument measured the resistance value 47.4KΩ, with an error of 2.5%. Program introduction None. I am not good at academics, so I need to hire external help to write the code, but the code has not been written yet. This is the summary of this version. Other functional debugging will be tested in the next version. Bye-Bye.