This IC 555 software calculates the values of the resistors and capacitors for a NE555 timer chip, which is designed as a astable multivibrator (oscillator), or square wave generator. You simply have to type in the duty cycle and the frequency and the calculator will work out realistic values for the resistors and capacitors.
Alternatively, you can insert the RA, RB and C values manually to check what corresponding output results you get for the frequency and the Duty cycle, and then you can change the figures accordingly until the intended results are determined.
Please remember that the lowest duty cycle will be 50 %, therefore should you need a smaller duty cycle you will need to apply an inverter on the output, by ticking the check box.
Furthermore the parameters explained in the equations of the IC 555 astable timer are only estimations which can be inaccurate by approximately 20% from the empirical outcomes.
NE555 Circuit Schematic

Equations:
F=1/T= 1.44/((RA+RB*2)*C)
TL= 0.693*RB*C
TH= 0.693*(RA+RB)*C
D= Duty Cycle= (RA+RB)/(RA+2*RB)
Or,
RA= 1.44**(2*D-1)/(F*C)
RB= 1.44*(1-D)/(F*C)
I am not understanding where the frequency, F appears on the NE555 chip. Is it within the chip or at the terminal 3. you can also explain who the switching frequency on the mosfet is achieve to finally have a 220V, 50Hz output on a grid tie solar inverter.
It is at pin 3 of the IC. For a 555 inverter you can refer to the following post
6 Best IC 555 Inverter Circuits Explored
I am looking at making a circuit that will be off for 30 seconds then on for 10 minutes when power is applied to the circuit
hello sir
iam sorry for language
but i need timer used for home
off about 20 minute and on about 1 minute and repeat it
Hello Rami, you can probably try the first circuit from this article:
https://www.homemade-circuits.com/how-to-make-simple-programmable-timer/
I need a 555 Pulse Generator Circuit with independent dynamics in both frequency and duty cycle i.e as I adjust the potentiometer one, it must not affect the other. Also the duty cycle should be from 0% to 100%.
Could you please help me with one?
You can use the second circuit from this article:
https://www.homemade-circuits.com/pwm-motor-soft-start-circuit/
the two pots will provide the PWM ans freq control separately
Swag sir…
How i find the 1000uF capacitor with 25V ?
I want to make a low high cut out circuit using relays for 12 v0lt car battery using IC or Transistor
you can use the following concept, remove the transformer and wire the relay with the desired load
https://www.homemade-circuits.com/simple-mains-ac-over-voltage-and-under/