555 timer + 74 series chip to build eight way responder, 30s countdown, proteus simulation, etc

The design requirements
1. Design a system based on digital circuit 30 Second timing responder , It can be used for 8 Person or 8 Team game ;

2. Set a control switch for the program host , It is used to control system reset and start rush answer ;

3. The responder has the functions of data latch and display . After the rush start , If a contestant answers successfully , The player number is locked immediately , The nixie tube displays the contestant's number , At the same time, the countdown stops , The buzzer gives a warning tone ;

4. After the contestant's answer is successful , Immediately block the input circuit , No other contestants are allowed to answer , Until the host resets the system and starts the next round of rush answer ;

5. If the countdown is over , There are still no contestants to answer , Then this rush answer is invalid , The system gives a short alarm , And block the input circuit , Players are not allowed to rush to answer after overtime , Countdown nixie tube display 00, Wait for the host to reset ;

6. The timer of the responder can pass through the counter 74LS192 Port high and low level configuration ;

Design Overview
The answer button of the responder is simulated by eight keys , after 74LS148 Encoder 、74LS373 Latch 、74LS48 The decoder and 7 Segment nixie tube realizes .

The clock signal used for the countdown function is determined by 555 The output of the multivibrator modified by the oscillator , The output signal is connected with two 74LS192 Connected to a , Adjust the countdown cycle through the number setting function , And 74LS192 Connected is 74LS48 The decoder and 7 Segment nixie tube .

The whole circuit consists of a power supply and a SPDT Switch （ Host button ） The control of the , Played the role of referee , The whole system design framework is shown in the figure below .

Simulation circuit diagram


Analysis of simulation results
Use Proteus 8.6 Software on “ Eight way responder .pdsprj” Simulation file , After opening , First make sure the host switches on and off SW1 Play to the left （ Left ： Timer reset ; Right ： The answer begins ）, If on the right , Mouse click SW1 Side red left and right arrows , Turn the switch to the left .

In the observation diagram ,8 Contestants are numbered 0~7.

Run the simulation , The simulation results are shown in the figure below . The contestant number nixie tube has no display , The countdown nixie tube display stays at 30, Wait for the host to switch SW1 Dial to the right , At this time, the system is ready to answer , It is invalid for the contestant to answer in preparation .

When the host reads out the title, he says “ Start ”, take SW1 Turn the switch to the right , a burglar alarm SPEAKER issue 3 Beep, beep ,30 The second countdown begins ,8 Contestants can now start to answer .

When a contestant answers successfully , The contestant number nixie tube displays the contestant number , The countdown stops , The alarm goes off 3 Beep, beep, beep .

Suppose the number is 5 Our contestants are counting down to 17 seconds , Answer successfully , The results are shown below .

After the contestant's answer is successful , Player number display nixie tube and countdown nixie tube are locked , It is invalid for other players to rush to answer again .

if 30 At the end of the countdown , There are still no contestants to answer , At this time, the player number nixie tube remains in the state of no display , Countdown nixie tube display 00, The alarm goes off 3 Beep, beep , Indicates that this round of rush answer is invalid .

After the rush answer , The host will SW1 Turn the switch to the left , Reset the system . The display of contestant number nixie tube is clear , The countdown nixie tube is reset to 30 second , Prepare for the next round of rush answers .

The countdown time can be changed , The method is to set two pieces 74LS192（ The number is U9 and U10） Four inputs of P0～P3 High and low levels to achieve .

Suppose you set the countdown time to 20 second , be U9 Of P0、P1、P2 and P3 Should be set to 0、1、0、0, and U10 Of P0、P1、P2 and P3 Should be set to 0、0、0、0, In this way 20 Second countdown function .

Resource content
（1） Eight way Responder design paper based on digital circuit complete version ;

（2）Proteus Simulation file ;

（3） Schematic diagram ;

（4） List of components ;

（5） Reference material ;

（6）Visio flow chart ;

Resource screenshot



Say the important thing again ！！！

Obtain a complete set of design data for the design of eight way responder ！

WeChat search for my official account ： Jiaoyuan Xiaozhi