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Quiz Monitor
This project is designed to see who is the first to be ready to answer a question in a quiz.
It can monitor 4 people (or two can be connected together to monitor two teams of up to four people each).
 
When the question is asked, the first person who pushes his/her button will cause a led to light and a buzzer to sound.  
The pushing of a button also, of course, disables the other players' buttons.
The led identifies the person and the buzzer can be made to have a different sound/pitch to identify the team.  
Once the fastest person has been indicated by the quiz monitor, the "question person" can push the reset button.
Alternatively, a simple auto-reset network can be included to reset the system after a few seconds.  
   
The circuit uses two chips: a 4584 hex Schmitt inverter and a 4076 quad D type latch.  
   
 
   
The unmarked resistors can all be around 100k and the capacitors, 0.1μ.  
For the reset network, use a capacitor of, say 10μ and find a value of resistor that gives a suitable delay (probably a few k).  
The two inverters connected to the clock input of the 4076 are used just to avoid leaving them unconnected.  
Now I look at this again (after quite a few years!) I can't help thinking they could have been used more productively, maybe to form an oscillator to make the sound when a button is pushed...  
   
Vero board, copper side  
   
 
   
Vero board, component side  
The (optional) auto-reset components are shown in red.  
If this is used, you might need to omit the manual reset resistor but the manual reset switch can still be used.  
   
 
Points 1, 2, 3, and 4 go to the leds.
The leds' cathodes are all connected to point B.  
S1 to S4 are the connections to the push button switches held by the contestants.  
The other side of each switch is to ground (battery negative).  
Points A, B and ground and battery positive are connected to the second quiz monitor.  
   
The photos below show one version of the 4 person monitor (with just one switch connected).  
Front panel: led indicators.  
   
 
   
Back panel: sockets for connecting push buttons.  
   
 
   
Side panel: on/off switch and charging sockets (plus connections for external battery in emergency!)  
   
 
   
Side panel: sockets to connect to a second monitor.  
   
 
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