555 monostable timer
Pulse duration and trigger-release check for a standard 555 one-shot.
Development preview. Check the assumptions below before relying on a result. Calculations run in your browser.
How it calculates
Model: t=−RC ln(1−2/3)=ln(3)RC≈1.1RC
Assumptions
- Standard one-shot is not an edge-retriggerable timer while its output remains high. A trigger held low past the timing threshold can extend the pulse; it must be released before timeout.
- Timing starts with a discharged capacitor; threshold/loading errors are not included.
Worked example
These are the calculator's default inputs. Change any input above to recalculate.
Inputs
- Mode
- analyse
- Timing resistance
- 100000 Ω
- Timing capacitance
- 0.000001 F
- Requested duration
- 0.1 s
- Trigger-low pulse width
- 0.001 s
- Supply voltage for waveform
- 5 V
Results
- Nominal high duration
- 0.109861 s
- Timing resistance
- 100000 Ω
- Trigger release margin
- 0.108861 s