getting problem in simulation of astable multivibrator with 50% duty cycle using 555 timer on proteus..... can someone help????
schematic is attached

 

I am one of the people who consider themselves an expert on the 555 timer here. Since you did not provide a schematic (which is tradition for all new folks here) I will provide some resources for 555's. As for proteus, I do not use simulators, I use the one between my ears.

http://forum.allaboutcircuits.com/picture.php?albumid=41&pictureid=308
http://forum.allaboutcircuits.com/picture.php?albumid=41&pictureid=1233

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