The 555 is an industrial standard timer IC, this app calculates about it.

FEATURES
- Can limit the values of resistors/capacitor to E3/E6/E12/E24 series.
- Simple waveform which will be output.
- Calculating the frequency and duty cycle from resistors/capacitor.
- Reverse calculating the values of resistors/capacitor from frequency and duty cycle. And list up recommended parts.
- Supported operation is only Astable.

HOW TO USE #1
(1) Please input the values of resistor Ra, Rb and capacitor C.
(2) A frequency, duty cycle, and waveform are output.

HOW TO USE #2
(1) Please input the frequency and duty cycle.
(2) A list of recommended parts (resistor Ra, Rb and capacitor C) is output.
(3) Can use one of the list as the input of 'HOW TO USE #1', and can calcurate it again.