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555 monostable (one-shot)

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Open this experiment in the circuit simulator

Objective

A short low pulse on TRIG makes the 555 output go high for T = 1.1·R·C.

Procedure

Run and measure the output pulse width on the Waveforms tab.
Change C to 22 µF: the pulse becomes 242 ms.

Theory

The timing capacitor charges through R toward VCC and the output returns low when it reaches 2/3 VCC: T = 1.1·R·C = 1.1 · 10 kΩ · 10 µF = 110 ms.

Questions to answer

What happens if a second trigger arrives during the pulse?

Components used

Battery / DC source, Electrolytic Capacitor 100uF 25V, Function generator (square), Oscilloscope (2-channel), 2 × Resistor 220 ohm 1/4W, Timer NE555

About the model

Ideal wires; component models as listed in the catalogue (no parasitics, no temperature drift). Built without a breadboard so the schematic stays readable.