It provides access to the internal voltage divider (2⁄3 VCC by default). Hence if this pin is not to be used for reset purposes, it should be connected to + VCC to avoid any possibility of false triggering. When a negative pulse is applied to pin 4 then IC becomes reset or disable.

Pin-4 is the reset terminal, which is used to disable or reset the timer. The load connected between output and ground pin is called the normally offload. The load connected between output and ground supply pin is called the normally on load.Ģ. There are two ways in which a load can be connected to the output terminal. Pin-3 is an output pin, which is normally connected to a load. So simply we can say that The output of the timer depends on the amplitude of the external trigger pulse that is applied to the trigger pin The 555 timer OUT Pin goes high and a timing interval starts when the trig pin input voltage falls below ½ of CONTROL voltage.

Pin-2 is a trigger pin that is Responsible for the transition of the flip-flop from set to reset. The ground reference voltage (zero volts).

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