|
| 1 | +from __future__ import annotations |
| 2 | + |
| 3 | +""" |
| 4 | + Calculate the frequency and/or duty cycle of an astable 555 timer. |
| 5 | + * https://en.wikipedia.org/wiki/555_timer_IC#Astable |
| 6 | +
|
| 7 | + These functions take in the value of the external resistances (in ohms) |
| 8 | + and capacitance (in Microfarad), and calculates the following: |
| 9 | +
|
| 10 | + ------------------------------------- |
| 11 | + | Freq = 1.44 /[( R1+ 2 x R2) x C1] | ... in Hz |
| 12 | + ------------------------------------- |
| 13 | + where Freq is the frequency, |
| 14 | + R1 is the first resistance in ohms, |
| 15 | + R2 is the second resistance in ohms, |
| 16 | + C1 is the capacitance in Microfarads. |
| 17 | +
|
| 18 | + ------------------------------------------------ |
| 19 | + | Duty Cycle = (R1 + R2) / (R1 + 2 x R2) x 100 | ... in % |
| 20 | + ------------------------------------------------ |
| 21 | + where R1 is the first resistance in ohms, |
| 22 | + R2 is the second resistance in ohms. |
| 23 | +""" |
| 24 | + |
| 25 | + |
| 26 | +def astable_frequency( |
| 27 | + resistance_1: float, resistance_2: float, capacitance: float |
| 28 | +) -> float: |
| 29 | + """ |
| 30 | + Usage examples: |
| 31 | + >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=7) |
| 32 | + 1523.8095238095239 |
| 33 | + >>> astable_frequency(resistance_1=356, resistance_2=234, capacitance=976) |
| 34 | + 1.7905459175553078 |
| 35 | + >>> astable_frequency(resistance_1=2, resistance_2=-1, capacitance=2) |
| 36 | + Traceback (most recent call last): |
| 37 | + ... |
| 38 | + ValueError: All values must be positive |
| 39 | + >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=0) |
| 40 | + Traceback (most recent call last): |
| 41 | + ... |
| 42 | + ValueError: All values must be positive |
| 43 | + """ |
| 44 | + |
| 45 | + if resistance_1 <= 0 or resistance_2 <= 0 or capacitance <= 0: |
| 46 | + raise ValueError("All values must be positive") |
| 47 | + return (1.44 / ((resistance_1 + 2 * resistance_2) * capacitance)) * 10**6 |
| 48 | + |
| 49 | + |
| 50 | +def astable_duty_cycle(resistance_1: float, resistance_2: float) -> float: |
| 51 | + """ |
| 52 | + Usage examples: |
| 53 | + >>> astable_duty_cycle(resistance_1=45, resistance_2=45) |
| 54 | + 66.66666666666666 |
| 55 | + >>> astable_duty_cycle(resistance_1=356, resistance_2=234) |
| 56 | + 71.60194174757282 |
| 57 | + >>> astable_duty_cycle(resistance_1=2, resistance_2=-1) |
| 58 | + Traceback (most recent call last): |
| 59 | + ... |
| 60 | + ValueError: All values must be positive |
| 61 | + >>> astable_duty_cycle(resistance_1=0, resistance_2=0) |
| 62 | + Traceback (most recent call last): |
| 63 | + ... |
| 64 | + ValueError: All values must be positive |
| 65 | + """ |
| 66 | + |
| 67 | + if resistance_1 <= 0 or resistance_2 <= 0: |
| 68 | + raise ValueError("All values must be positive") |
| 69 | + return (resistance_1 + resistance_2) / (resistance_1 + 2 * resistance_2) * 100 |
| 70 | + |
| 71 | + |
| 72 | +if __name__ == "__main__": |
| 73 | + import doctest |
| 74 | + |
| 75 | + doctest.testmod() |
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