LM555 Simulator · catto.ar

About this simulator

The LM555 in its two modes: astable, when it oscillates, and monostable, when it delivers a single pulse. You choose the values of R1, R2 and C and see at the same time how the capacitor charges and discharges and what shape the output takes, with the times calculated.

Besides the direct calculation it includes inverse design —which resistors and which capacitor are needed for the time you want— and an explanation of why the chip is called 555: the three equal resistors of the internal divider, the two comparators, the flip-flop and the discharge transistor. There you can see where the constants 0.693 and 1.1 in the formulas come from.

Within the Electronics Technician program this content is covered in Oscillators, Sequential logic and Special semiconductors.

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