elementary question on 555 timer ?

[desperado1]

In the following timer circuit's block diagram whenever threshold pin is greater than 2/3 of Vcc and trigger is greater than 1/3 of Vcc. We have R=S=1 .............but we know that R=s=1 is an indeterminate state in R-S flip flop. In this case
what would be the output ?

Also,
is it possible to have R=S=1 inside the flip flop of 555 timer ? In that case what could be the output ?

 

[kspalla]

it is not possible to have R=S=1
Any potential is checked is it less than 1/3 V then S=1,
if this potential is greater than 2/3V then R=1
as the voltage is increasing from 1/3 to 2/3 as soon it exceed 1/3V then S= 0
This is typical application.

 

[xulfee]

some where u can get R=S,at that point output will be same as previous

 

[desperado1]

it is not possible to have R=S=1
Any potential is checked is it less than 1/3 V then S=1,
if this potential is greater than 2/3V then R=1
as the voltage is increasing from 1/3 to 2/3 as soon it exceed 1/3V then S= 0
This is typical application.

thanks for the reply..........why is always a negative trigger given to the trigger ? can't we give a positive pulse and still make a monostable multivibrator.......

 

[saty.satya]

it is possibe 2 have s and r at 1 but when these are 1 the upper transistor will not work (which is not shown in the diagram)

 

[desperado1]

it is possibe 2 have s and r at 1 but when these are 1 the upper transistor will not work (which is not shown in the diagram)

can u please elaborate the point ?