TheAlgorithms-Python

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from __future__ import annotations
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"""
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    Calculate the frequency and/or duty cycle of an astable 555 timer.
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    * https://en.wikipedia.org/wiki/555_timer_IC#Astable
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    These functions take in the value of the external resistances (in ohms)
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    and capacitance (in Microfarad), and calculates the following:
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    -------------------------------------
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    | Freq = 1.44 /[( R1+ 2 x R2) x C1] |               ... in Hz
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    -------------------------------------
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    where Freq is the frequency,
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          R1 is the first resistance in ohms,
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          R2 is the second resistance in ohms,
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          C1 is the capacitance in Microfarads.
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    ------------------------------------------------
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    | Duty Cycle = (R1 + R2) / (R1 + 2 x R2) x 100 |    ... in %
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    ------------------------------------------------
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    where R1 is the first resistance in ohms,
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          R2 is the second resistance in ohms.
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"""
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def astable_frequency(
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    resistance_1: float, resistance_2: float, capacitance: float
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) -> float:
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    """
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    Usage examples:
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    >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=7)
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    1523.8095238095239
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    >>> astable_frequency(resistance_1=356, resistance_2=234, capacitance=976)
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    1.7905459175553078
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    >>> astable_frequency(resistance_1=2, resistance_2=-1, capacitance=2)
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    Traceback (most recent call last):
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        ...
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    ValueError: All values must be positive
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    >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=0)
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    Traceback (most recent call last):
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        ...
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    ValueError: All values must be positive
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    """
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    if resistance_1 <= 0 or resistance_2 <= 0 or capacitance <= 0:
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        raise ValueError("All values must be positive")
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    return (1.44 / ((resistance_1 + 2 * resistance_2) * capacitance)) * 10**6
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def astable_duty_cycle(resistance_1: float, resistance_2: float) -> float:
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    """
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    Usage examples:
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    >>> astable_duty_cycle(resistance_1=45, resistance_2=45)
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    66.66666666666666
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    >>> astable_duty_cycle(resistance_1=356, resistance_2=234)
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    71.60194174757282
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    >>> astable_duty_cycle(resistance_1=2, resistance_2=-1)
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    Traceback (most recent call last):
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        ...
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    ValueError: All values must be positive
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    >>> astable_duty_cycle(resistance_1=0, resistance_2=0)
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    Traceback (most recent call last):
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        ...
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    ValueError: All values must be positive
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    """
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    if resistance_1 <= 0 or resistance_2 <= 0:
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        raise ValueError("All values must be positive")
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    return (resistance_1 + resistance_2) / (resistance_1 + 2 * resistance_2) * 100
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if __name__ == "__main__":
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    import doctest
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    doctest.testmod()
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