We know that astable multivibrator is simply an oscillator circuit that produces continuous pulses without the help of any external triggering. The oscillation frequency and time period can be manually controlled through simple modification of resistors and capacitors i.e. by changing the values of R1, R2 and C1. You can use a 555 timer astable calculator tool to make your designing easier.
Astable 555 calculator for calculating Frequency and Time period
We had already discussed the 555 timer tutorial of astable multivibrator in detail with animation. Though we provided the design equation there, one of our reader Mr Dewanto asked:"I need Ton=3 seconds, and Toff= 15 minutes. how can I modify the capacitor then?"So we thought about creating an astable 555 timer calculator. With this 555 timer IC astable calculator you can calculate frequency, duty cycle (in percent), high and low output time periods to meet your requirements.We have also come up with a monostable frequency calculator tool. You can also have a look at that for monostable pulse duration calculation.
Reference circuit diagram of astable multivibrator using 555 timer