Here is a monostable multivibrator using IC CD4538. It is a precision monostable/astable multivibrator IC free from false triggering. This can be used for various application in which precise timing cycle is required.
CD4538 is the precision monostable/astable multivibrator IC that is free from false triggering. It is more reliable than the popular timer IC 555. Here the IC is wired as a short duration monostable timer using R1 and C1 as timing components. With the given values, output of IC1 remains low for three minutes. By changing the value of C1 or R1 various time intervals can be obtained.
Unlike 555 IC in the monostable mode, here in CD4530, output of IC becomes high at power on and becomes low when the trigger pin5 gets a low-to-high transition pulse. When S1 is pressed, the high going pulse triggers IC and its output goes low. This drives the load through the PNP transistor T1.Load can be an LED, Buzzer etc.