RF555 Astable Multivibrator Calculator: Frequency & Duty Cycle
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This page provides calculators for determining the frequency and duty cycle of a 555 astable multivibrator. It also covers the formulas used in these calculations, employing two different methods.
555 Astable Multivibrator Calculator - 1
This calculator uses the resistor values (R1 and R2) and the capacitor value (C) as inputs to calculate the frequency and duty cycle of the 555 astable multivibrator.
Inputs: R1, R2, C
Outputs: Frequency, Duty Cycle
Example:
INPUTS: R1 = 10 kΩ, R2 = 10 kΩ, C = 0.220 µF (220 nF)
OUTPUT: Frequency = 218.1818 Hz, Duty cycle (%) = 66.67%, t HIGH = 0.003049 Sec, t LOW = 0.001524 Sec
Figure 1: Pin diagram of 555 IC used as astable multivibrator.
The following formula is used for the frequency and duty cycle calculation:
555 Astable Multivibrator Calculator - 2
This calculator uses the desired frequency, duty cycle, and capacitor value (C) as inputs to calculate the required resistor values (R1 and R2).
Inputs: Frequency, Duty Cycle, C
Outputs: R1, R2
Example:
INPUTS: Frequency = 218 Hz, Duty Cycle = 0.60, C = 0.220 µF
OUTPUT: R1 = 6 kΩ, R2 = 12 kΩ
The following formula is used for the resistor calculation:
Astable Multivibrator Calculator - 3 (using NOT Gates)
This calculator determines the frequency and time period of an astable multivibrator built using NOT gates or inverter gates.
Inputs: Number of NOT gates, Propagation delay of each gate
Outputs: Time period, Frequency
Example:
Inputs: Number of gates = 3, Propagation delay of each gate = 1 ns
Outputs: Time period of square wave = 6 ns (6.0 x 10-9 s), Frequency of square wave = 166,666,666 Hz (166.666666 MHz)
Figure: Bistable and astable multivibrator (AMV) made using NOT gates (i.e., inverter gates).
The following formula is used to calculate the frequency and time period:
Time period of AMV, T = 2 * n * tpd
Where:
- n = Number of inverter gates or NOT gates
- tpd = Propagation delay time of each inverter
- T = Time period of square wave generated by AMV or ring oscillator.
Frequency of AMV (f) = 1/T = 1 / (2 * n * tpd)
