The eight-way answering device designed in this internship has not only the basic answering function, but also the alarm function. The circuit can answer eight channels first at the same time. After pressing the button, the circuit will beep and display the number of the first answer number. After the successful answer, press the button first, and the display screen will not change unless the reset button is pressed. After reset, the display shows that you can continue to answer first. The whole circuit includes the answer-first, coding, priority, latch, number and reset circuit, and SB 1 to SB8 is the answer-first key. SB9 is reset, and CD45 1 1 is an integrated circuit integrating BCD-7 latching, decoding and driving circuits. It adopts 74 ls 148 to realize the gating of the transponder. 74 l279 chip is used to latch decimal numbers, 74 ls 192 counter is used to latch decimal numbers, and 555 chip is used to generate pulse signals for alarm signals.

This practice improves and consolidates the basic knowledge learned through course design, and comprehensively applies welding knowledge and technology.

Key words: buzzer, coding, decoding, alarm.