This product is a 4-digit electronic clock kit that requires welding and assembly by yourself. It is suitable for installation and study by electronic enthusiasts and major electronic vocational schools. The program for the microcontroller has passed the exam, and no electronic version of the program will be provided. Power supply: DC3.7V-5.5V Special reminder: If you use it for a long time, it is recommended to use a DC power supply, because if you use ordinary 3 AA batteries, it will consume power quickly and is not suitable for long-term use. Function introduction: 1. Normal running time, hours and minutes display. 2. Hours and minutes are independently adjustable. 3. Time second correction function. 4. You can fine-tune the speed of the clock, 0--9 levels are adjustable, the default is level 5. 5. Two-way alarm clock, and the alarm switch can be set independently. 6. The hourly reminder function can be turned off and on. 7. Equipped with a battery interface, which can run time when the power is turned off. The battery only needs to be greater than 3V to ensure running time after power failure. You can use two AA batteries, three AA batteries, or mobile phone batteries. 8. The function can be realized within 99 minutes and the alarm will end. 9. Stopwatch function, which can realize the stopwatch function, pause the stopwatch, and clear the stopwatch. 10. It can realize the counter function and record the number of key presses. The number of external pulses can also be recorded. Material: plastic colour: As Shown size: about 53 x 40mm Package Contents: 1 x Electronic Clock DIY Kit 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.