When you first power on, the LCD will have a white screen of about 2 seconds. This is because the program is designed in this way. The system will calculate some initial references needed for the subsequent measurement after power-on for 2 seconds. In addition to the power switch being pressed, other switches in the white screen range are required to pop up. If the switch is pressed, the subsequent measurement data will be inaccurate. Remember! After 2 seconds of white screen, the LCD will display: F/C/L Tester, and then you can start to measure the parameters of the components you want. For example, to measure the non-polar capacitance, connect the non-polar capacitance and then press the "test switch of non-polar capacitance". For example, to measure the inductance, connect the inductance and then press the "inductance test switch". Only one of the five function switches can be pressed at the same time. When testing what is pressed, the requirements that are not used will pop up. When testing nonpolar capacitors, inductors, and polar capacitors, these components are connected to the test stand regardless of polarity. For frequency testing, it is necessary to distinguish polarity. Note that. If it is the first time to use the purchased kit after welding, you need to adjust the brightness of the LCD. After 2 seconds of power on, adjust the 10K potentiometer on the top of the board to make the display effect of the 1602 reach a better state. Specification: Item name: 51 Single-chip Microcomputer Inductance and Capacitance Frequency Meter DIY Electronic Kit Working voltage: DC9V Capacitance measurement range: 1pF - 1nF Inductance measurement range: 1uH-100uH Frequency measurement range: 0-50KHz Note: It's diy kits. Need to solder by yourself. There are differences in components between different batches, which