NE555 Timer Calculator
The 555 timer is one of the most popular chips ever made, and it runs in two classic modes. In astable mode it oscillates continuously, and in monostable mode it fires a single timed pulse when triggered. This calculator handles both. For astable mode enter the two resistors Ra and Rb and the timing capacitor to get the output frequency, the period, and the duty cycle using the standard 1.44 divided by Ra plus two Rb times C relationship. For monostable mode enter one resistor and the capacitor to get the one shot pulse width, which is 1.1 times R times C. These formulas match the classic bipolar NE555, so you can design blinkers, tone generators, delays and pulse stretchers with confidence. Enter your parts, choosing convenient units, and read the timing instantly in your browser.
How to use NE555 Timer Calculator
- Select astable or monostable mode.
- Enter R1 and R2 for astable, or the single R for monostable.
- Enter the timing capacitor value.
- Read the frequency, period and duty cycle, or the one shot pulse width.
Frequently asked questions
What is the difference between the 555 astable and monostable modes?
Astable mode oscillates continuously to give a frequency and duty cycle, while monostable mode fires a single output pulse of a set width when triggered.
How is astable frequency calculated?
It uses the classic 1.44 divided by (R1 plus 2 times R2) times C relationship to give the output frequency, then derives period and duty cycle from it.
How is the monostable pulse width found?
A one shot pulse lasts 1.1 times R times C seconds, so the tool multiplies your resistor and capacitor to report the exact pulse duration.
What is NE555 Timer Calculator?
The 555 timer is one of the most popular chips ever made, and it runs in two classic modes. In astable mode it oscillates continuously, and in monostable mode it fires a single timed pulse when triggered.
Is NE555 Timer Calculator free to use?
Yes. NE555 Timer Calculator is completely free, with no sign-up and no usage limits.
Does NE555 Timer Calculator work in a web browser?
Yes. NE555 Timer Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with NE555 Timer Calculator?
Yes. NE555 Timer Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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