Finished product display
This kit contains 0805 packaged resistor, capacitor, SMD aluminum capacitor, SMD resistor, SMD crystal oscillator, SMD LED lamp, SMD diode, SOP14, SOP20, TQFP44 and other packaged SMD chips. There are 12 groups of SMD test areas. The welding difficulty is from low to high. Each group can be tested independently. It has short circuit and false soldering test functions. It can judge whether the welding is successful according to the display of LED lamp, A total of 314 SMD welding components are included. By welding, the welding ability, speed and circuit maintenance ability of various SMD components can be improved to meet the difficulty of the competition. With self inspection function, the welding results and welding errors can be seen after power on.
Principle description:
1. J1 and J2 are the power supply input terminals of the whole chip board, which can work normally when connected with AC6v. When it works normally, all the LED lights of the kit can work normally. At first, each group of LED flashes in running water, and then flashes at intervals. Finally, all the LED lights are on, and then flashes. This cycle is used to check whether the LED works and whether the LED is welded well. If the corresponding LED does not flash, it indicates that there is an error or false welding.
2. AC9V power supply is rectified by D1-D4 diode, and then goes through each filter capacitor to the 1 pin of voltage regulator chip 78M05 (LED97 is always on, the rectifier circuit works normally), and outputs DC5V through 3 pins to supply the whole test circuit.
3. The test circuit is controlled by a single chip microcomputer 12 groups of 8-bit LED lamp work. Each group is composed of one 74HC573 and 74HC164. A group can control 8 LEDs, a total of 12 groups. When it works normally, all the LEDs are on and can flash.