555 timer

                                           

                      today the topic is that what is 555 timer 

the pin diagram of 555 timer is that &-this more stable device 

 the 555 timer  can works in three mode .the modes names are given below-

1).monostable operation                                                                               

2).bistable operation                                                                                       

3).astable operation                                                                                         

the functional diagram of 555 timer is that                                                        

      this circuit consist of there are two comparator first is upper comparator and another is lower                  comparator .non inverting terminal or pin no.5 of the upper comparator is contain 2/3 of Vcc ,            inverting terminal of the lower comparator is contain 1/3 of Vcc.output of the both comparator             goes to the SR flipflop which is working that when both inputs are low(0)then output is not                change but if S=1&R=0 then flipflop works in set mode and if S=0&R=1 then flipflop works in the  reset mode .trigger switch is used to operate in different -2 mode and discharge pin no.7 is work when reset pin is high .the name of 555 timer is called bcz there are three resistors are used  .

in short form the operation modes of 555 timer is that -