555 timer IC is very commonly used to produce time delays in monostable mode. The IC produces a time delay every time its trigger pin 2 is given an active low signal. The time of the delay is decided by the value of resistance and capacitance. However, in many applications it is required to trigger 555 whenever the output goes high. This circuit based project addresses to the aforesaid problems. The circuit in this project uses an npn transistor T1 to achieve the above objective. 555 timer in monostable configuration is shown in the figure. Pin 2, which is the trigger pin of the IC is connected to the collector of T1. Continue reading to find out how the circuit is connected and how it works.