Added 555 timer duty cycle and freqency in astable mode.

electronics/ic_555_timer.py

@@ -0,0 +1,75 @@
+from __future__ import annotations
+
+"""
+    Calculate the frequency and/or duty cycle of an astable 555 timer.
+    * https://en.wikipedia.org/wiki/555_timer_IC#Astable
+
+    These functions take in the value of the external resistances (in ohms)
+    and capacitance (in Microfarad), and calculates the following:
+
+    -------------------------------------
+    | Freq = 1.44 /[( R1+ 2 x R2) x C1] |               ... in Hz
+    -------------------------------------
+    where Freq is the frequency,
+          R1 is the first resistance in ohms,
+          R2 is the second resistance in ohms,
+          C1 is the capacitance in Microfarads.
+
+    ------------------------------------------------
+    | Duty Cycle = (R1 + R2) / (R1 + 2 x R2) x 100 |    ... in %
+    ------------------------------------------------
+    where R1 is the first resistance in ohms,
+          R2 is the second resistance in ohms.
+"""
+
+
+def astable_frequency(
+    resistance_1: float, resistance_2: float, capacitance: float
+) -> float:
+    """
+    Usage examples:
+    >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=7)
+    1523.8095238095239
+    >>> astable_frequency(resistance_1=356, resistance_2=234, capacitance=976)
+    1.7905459175553078
+    >>> astable_frequency(resistance_1=2, resistance_2=-1, capacitance=2)
+    Traceback (most recent call last):
+        ...
+    ValueError: All values must be positive
+    >>> astable_frequency(resistance_1=45, resistance_2=45, capacitance=0)
+    Traceback (most recent call last):
+        ...
+    ValueError: All values must be positive
+    """
+
+    if resistance_1 <= 0 or resistance_2 <= 0 or capacitance <= 0:
+        raise ValueError("All values must be positive")
+    return (1.44 / ((resistance_1 + 2 * resistance_2) * capacitance)) * 10**6
+
+
+def astable_duty_cycle(resistance_1: float, resistance_2: float) -> float:
+    """
+    Usage examples:
+    >>> astable_duty_cycle(resistance_1=45, resistance_2=45)
+    66.66666666666666
+    >>> astable_duty_cycle(resistance_1=356, resistance_2=234)
+    71.60194174757282
+    >>> astable_duty_cycle(resistance_1=2, resistance_2=-1)
+    Traceback (most recent call last):
+        ...
+    ValueError: All values must be positive
+    >>> astable_duty_cycle(resistance_1=0, resistance_2=0)
+    Traceback (most recent call last):
+        ...
+    ValueError: All values must be positive
+    """
+
+    if resistance_1 <= 0 or resistance_2 <= 0:
+        raise ValueError("All values must be positive")
+    return (resistance_1 + resistance_2) / (resistance_1 + 2 * resistance_2) * 100
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()