When you on, the LCD have a white screen of about 2 seconds. This is because the program is designed in this way. The system 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 up. If the switch is pressed, the subsequent measurement data be inaccurate. Remember! After 2 seconds of white screen, the LCD display: /L Tester, and then you can start to measure the parameters of the components you want. For example, to measure the non- capacitance, connect the non- capacitance and then press the "test switch of non- 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 up. When testing nonpolar capacitors, inductors, and 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, whichdoes not affect the use Colour: Red+Green+Transparent Material: PCB+components+acrylic Package Contents: 1 x DIY kit with case(It's diy kits. Need to solder by yourself) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.