: A CMOS chip containing six independent Schmitt-trigger inverters. Resistor (
is the total time period of one full cycle. For a 74HC14 chip powered by a standard supply, the formula simplifies to:
For stable oscillation, it is recommended to keep to minimize the impact of stray capacitance.
The K‑factor encapsulates the effect of the Schmitt trigger’s hysteresis . For a 74HC14 at 5 V, the upper threshold (UTP) is about 3.3 V (≈ 0.66 Vcc) and the lower threshold (LTP) about 1.8 V (≈ 0.36 Vcc). Solving the charging/discharging RC equations yields the “0.8” factor. 74hc14 oscillator calculator full
$$f \approx \frac0.8R \times C$$
To build the oscillator, a single gate of the 74HC14 is wired with a feedback loop containing an RC network. Schematic Setup
): The input pins have a tiny amount of input leakage current (around : A CMOS chip containing six independent Schmitt-trigger
. The voltage across the capacitor rises exponentially toward VCCcap V sub cap C cap C end-sub Upper Threshold ( VT+cap V sub cap T plus end-sub
For example, with R = 10 kΩ and C = 0.1 µF:
Frequency will drift as ambient temperature affects the IC's internal switching thresholds. The K‑factor encapsulates the effect of the Schmitt
The precise formula accounting for the High ($V_T+$) and Low ($V_T-$) threshold voltages is:
$$t_low = R \times C \times \ln\left(\fracV_T+V_T-\right)$$
Instead of solving the exponential charging formula manually, you can use a dedicated online tool like the .