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Quiz Circuit(4081)

2017-08-04 05:49  
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This article briefly describes the Quiz Circuit (4081). This principle is easy to understand, but also very practical. Depth understanding of circuit elements, you can better grasp this principle. In this circuit, you can learn about and buy these components: 4081.

I’ve had a few requests for a quiz circuit, so here is a 4 input design which can easily be modified. Maybe, I should write the application notes in the style of a game show host…

Figure:1 Circuit diagram

Figure 1 Circuit diagram

This design uses four IC’s and has four input circuits and four independent outputs and a single master reset switch. The outputs here areLED’s but may be modified to drive lamps or buzzers. Only one outputLEDcan be lit at any time. The first person to press their input switch, A,B,C,D will light the corresponding outputLED, disabling the other inputs.

The circuit uses allCMOSIC’s part numbers shown on the diagram. The supply voltage may be anything between 3 and 15 volts. Alternatively, it may be built using equivalentTTLIC’s and powered on 5 volts. The main component in this circuit is a bistable latch, here it is based on the dual 4013 D-type flip flop.

Circuit Operation:
Pressing the reset switch will clear all flip flops and extinguish any litLED’s. Under this condition the Q outputs will all be low (logic 0) andNOTQ outputs will be high (logic 1). All fourNOTQ outputs are fed to a 4 inputANDgate, the 4082 whose output will also be high. The output of the 4082 is wired to one input of each 2 inputANDgate (4081). Switch inputs A,B,C,D are all non latching push button switches, the first person to press their switch will cause the correspondingANDgate (4081) to go high and trigger the preset input of the 4013 D-type flip flop.

This will latch and light the appropriateLED. Also the triggered flip flop will have itsNOTQ output, set at low, this changes the 4082 output to low and prevents any further triggering of the other flip flops. Switch contact de-bouncing is not required as the first press will latch one of the bistables. Pressing the reset switch, restores the circuit to its former state. I would recommend using heavy duty push button switches, as in use they are likely to be under some stress.



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