# NE555 Astable Circuit Calculator

In astable mode, the NE555 can be used to create an oscillating output between V_{CC} and 0V. All that is needed is a setup like in the following schematic:

Capacitor \((C)\): | ||
---|---|---|

Resistor \((R_1)\): | ||

Resistor \((R_2)\): |

By selecting proper values for \(R_1, R_2\) and \(C\), we can determine the frequency and duty cycle of the oscillation:

Frequency: | ▶ | |
---|---|---|

Period \((T)\): | ||

Duty Cycle: | ||

Time High \((T_1)\): | ||

Time Low \((T_0)\): |

A period is the time for one full on/off cycle to repeat itself and the duty cycle is the percentage of time the signal was high in one period. In a NE555 astable circuit, the duty cycle can never be below 50%.

## Reverse Calculator

The following calculator presents possible resistor and capacitor values, based on a desired frequency and duty cycle.

Frequency \((F)\): | Hz |
---|---|

Duty Cycle: | % |

Possible set ups: