74hc14 Oscillator Calculator: [top]

The circuit will oscillate at ~423 Hz. You can adjust with a trimmer cap or a series pot.

import math def hc14_oscillator(r_ohms, c_farads, v_cc=5.0, method="heuristic"): """ Calculate frequency and period for a 74HC14 RC oscillator. method: "heuristic" (0.55 constant) or "exact" (with thresholds) """ if method == "heuristic": freq = 1 / (0.55 * r_ohms * c_farads) else: # exact for 5V typical thresholds v_tplus = 3.15 # Typical at 25C, 5V v_tminus = 1.85 num = v_tplus * (v_cc - v_tminus) den = v_tminus * (v_cc - v_tplus) freq = 1 / (r_ohms * c_farads * math.log(num / den)) 74hc14 oscillator calculator

$f = \frac10.55 \times 430 \times 10^3 \times 10 \times 10^-9 = \frac10.55 \times 4.3 \times 10^-3$ $f = \frac10.002365 \approx 423 \text Hz$ The circuit will oscillate at ~423 Hz