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555 Timer LED Blinker

A pulse source drives an LED through a series resistor — watch it blink on the scope.

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555-astable.circuit transient analysis

How it works

A 555 timer in astable mode produces a continuous square wave. Here we model the output as a 2 Hz pulse source toggling between 0 V and 5 V, driving a red LED through a 220 Ω current-limiting resistor.

Run the transient analysis to watch the LED blink on and off. The voltage probe captures the square wave on the oscilloscope. Change the frequency in the pulse source properties to speed up or slow down the blink rate.