74hc14 Oscillator Calculator __exclusive__
To build a 74HC14 relaxation oscillator , the frequency is determined by a single resistor ( ) and capacitor ( ). Because the 74HC14 is an inverting Schmitt trigger
, it automatically cycles between high and low states as the capacitor charges and discharges through the resistor. 1. Frequency Formula
While specific chip manufacturers have slight variations due to internal threshold levels, the most common practical formula for a
f is approximately equal to the fraction with numerator 1 and denominator 0.8 center dot cap R center dot cap C end-fraction : Frequency in Hertz (Hz) : Resistance in Ohms ( : Capacitance in Farads (F) Alternative Estimation: Some sources use for a rougher, "rule of thumb" calculation. 2. Component Selection Guide
When choosing values for your circuit, keep these practical limits in mind: Resistor ( Use values between Avoid values below 1k to prevent excessive current draw from the output pin. Capacitor (
Non-polarized ceramic capacitors (e.g., 0.1µF or 0.01µF) are ideal for higher frequencies. Large electrolytic capacitors can be used for very slow blinkers (1Hz or lower) but may have leakage issues. Supply Voltage ( cap V sub cap C cap C end-sub The 74HC14 operates between
. Changing the voltage slightly shifts the frequency because the Schmitt trigger's internal thresholds scale with cap V sub cap C cap C end-sub Electrical Engineering Stack Exchange 3. Example Calculations (at 5V) Target Frequency Resistor ( Capacitor ( 4. How It Works
When power is applied, the capacitor is empty (0V). The Schmitt trigger sees a "Low" input and outputs "High" (~5V).
Current flows through the resistor from the High output to charge the capacitor. The Trigger: Once the capacitor voltage hits the Upper Threshold (~2.9V), the output instantly flips "Low" (0V). Discharging:
The capacitor now discharges through the same resistor into the Low output. The Reset: When the capacitor voltage drops to the Lower Threshold
(~1.9V), the output flips back to "High," and the cycle repeats. 5. Pro-Tips for Accuracy Threshold Variations:
The 74HC14 thresholds vary between brands (e.g., TI vs. NXP). For precision, you may need a Schmitt Trigger Oscillator Calculator
that allows you to input specific voltage thresholds from your datasheet. Buffering:
Using one of the 5 remaining gates on the chip as a "buffer" (connecting the oscillator output to the input of another gate) prevents external loads like LEDs from slowing down or stopping the oscillation. Stompbox Electronics schematic diagram for this circuit or help picking components for a specific target frequency
Schmitt Trigger Oscillator Calculator - Stompbox Electronics
The 74HC14 oscillator, specifically known as a Schmitt-trigger relaxation oscillator, is one of the simplest and most reliable ways to generate a digital square wave. Unlike standard inverters, the 74HC14 contains hysteresis, meaning it has two different switching thresholds ( VT+cap V sub cap T plus end-sub VT−cap V sub cap T minus end-sub ) that prevent noise from causing multiple triggers. 74HC14 Oscillator Calculation Formulas The frequency (
) of a 74HC14 oscillator is determined by a single resistor ( ) and a capacitor (
). While the exact frequency can vary slightly between manufacturers (like Nexperia or Texas Instruments), two common formulas are used for quick estimation: Standard Approximation:
f≈1.2R×Cf is approximately equal to the fraction with numerator 1.2 and denominator cap R cross cap C end-fraction Empirical Formula (More Precise):
f≈10.8×R×Cf is approximately equal to the fraction with numerator 1 and denominator 0.8 cross cap R cross cap C end-fraction For a time-period ( ) calculation:
T=1f≈0.8×R×Ccap T equals 1 over f end-fraction is approximately equal to 0.8 cross cap R cross cap C How the Circuit Works Charging Phase: When the output is HIGH, the capacitor ( ) charges through the resistor ( Upper Threshold ( VT+cap V sub cap T plus end-sub
): Once the voltage across the capacitor reaches the upper threshold (typically ≈2.9Vis approximately equal to 2.9 cap V
supply), the Schmitt-trigger inverter flips its output to LOW.
Discharging Phase: The capacitor now begins to discharge through the same resistor toward the LOW output. Lower Threshold ( VT−cap V sub cap T minus end-sub ): When the voltage falls to the lower threshold (typically ≈1.9Vis approximately equal to 1.9 cap V ), the output flips back to HIGH, and the cycle repeats. Design Considerations
74hc14 relaxation oscillator - NI Forums - National Instruments
Here’s an interesting, practical guide to designing oscillators with the 74HC14 (Schmitt-trigger inverter).
Unlike a regular logic gate, the 74HC14 has hysteresis — perfect for simple, stable RC oscillators without external timing components (like a 555 or crystal).
Part 4: Practical Design Guidelines (Beyond the Calculator)
A calculator gives a theoretical number. Real-world performance requires trade-offs.
Quick reference formulas
- t_charge = RC · ln[(VCC − V_T−)/(VCC − V_T+)]
- t_discharge = RC · ln[V_T+/V_T−]
- f = 1 / [RC · ( ln[(VCC − V_T−)/(VCC − V_T+)] + ln[V_T+/V_T−] )]
- Duty cycle = t_charge / (t_charge + t_discharge)
If you want, I can compute R or C for a specific VCC, target frequency, and chosen capacitor value — tell me VCC, desired frequency, and chosen C (or desired R).
The 74HC14 Schmitt Trigger Oscillator is a cornerstone of simple digital circuit design, prized for its ability to convert a steady DC supply into a periodic square wave using only a single resistor ( ) and capacitor ( The Mechanism of Oscillation
The circuit operates as a relaxation oscillator. Unlike standard inverters, the 74HC14 from Diodes Inc. features hysteresis, meaning it has two distinct threshold voltages: the positive-going threshold ( VT+cap V sub cap T plus end-sub ) and the negative-going threshold ( VT−cap V sub cap T minus end-sub
Charging Phase: When the circuit is powered, the capacitor begins to charge through the resistor toward the supply voltage ( VCCcap V sub cap C cap C end-sub ). Once the capacitor voltage ( VCcap V sub cap C VT+cap V sub cap T plus end-sub , the Schmitt trigger inverts its output to LOW (0V).
Discharging Phase: With the output now at 0V, the capacitor begins to discharge through the same resistor. When VCcap V sub cap C drops to the lower threshold VT−cap V sub cap T minus end-sub , the output flips back to HIGH ( VCCcap V sub cap C cap C end-sub ), and the cycle repeats. The Calculator Formula Calculating the frequency (
) of a 74HC14 oscillator isn't as straightforward as a standard 555 timer because the threshold voltages vary slightly with the manufacturer and supply voltage. However, a widely accepted approximation for
f≈11.2⋅R⋅Cf is approximately equal to the fraction with numerator 1 and denominator 1.2 center dot cap R center dot cap C end-fraction Alternatively, to find the time period (
T≈0.8⋅R⋅Ccap T is approximately equal to 0.8 center dot cap R center dot cap C Design Considerations Component Limits: Keep 74hc14 oscillator calculator
is too low, the output current might exceed the 74HC14's limits; if it's too high, input leakage current can cause instability. Hysteresis Variance: Because VT+cap V sub cap T plus end-sub VT−cap V sub cap T minus end-sub
are not perfectly fixed, this oscillator is excellent for clocking simple logic but is not recommended for high-precision timing applications where a crystal oscillator would be more appropriate.
Power Supply: Ensure you use a decoupling capacitor (typically 0.1µF) close to the IC's power pins to prevent noise from triggering false oscillations.
74HC14 oscillator , often called a relaxation oscillator, uses a single Schmitt-trigger inverter with one resistor ( ) and one capacitor (
) to create a steady square wave. The approximate oscillation frequency is typically given by the formula:
f is approximately equal to the fraction with numerator 1.2 and denominator cap R center dot cap C end-fraction
This simplified formula accounts for the specific hysteresis levels of the 74HC14 CMOS chip when powered at The Story of the 74HC14 Oscillator Imagine a tiny gatekeeper standing inside a chip—the Schmitt-trigger inverter
. This gatekeeper is notoriously stubborn: it only changes its mind (the output state) when things get extreme. The Rise (Charging) : At first, the capacitor is empty (
). The inverter sees this "Low" input and flips its output to "High" (
). Now, current begins to flow through the resistor, slowly filling the capacitor like water filling a bucket. The Hysteresis Threshold
: The gatekeeper (inverter) doesn't react as soon as the voltage hits . It waits until the capacitor reaches a specific Upper Threshold Voltage cap V sub cap T plus end-sub ), usually around cap V sub cap T plus end-sub is hit, the inverter suddenly flips its output to "Low" (
). Now, the bucket (capacitor) starts to drain back through the same resistor toward the "Low" output. The Fall (Discharging)
: As the voltage drops, the gatekeeper again waits. It won't flip back to High until the voltage falls all the way down to the Lower Threshold Voltage cap V sub cap L minus end-sub ), typically around
: Once it hits the lower floor, the output flips High again, and the cycle repeats forever. This constant "indecision" between two thresholds creates a perfect, repeating pulse—a heartbeat for your circuit. Component Calculation Guide To find your frequency, you can use the Stompbox Electronics Calculator or follow these steps manually: 1. Determine Target Frequency
Decide how fast you want the pulse to be. For example, if you want an LED to blink once per second, your frequency ( 2. Select a Capacitor (
Start with a common value. For slow pulses (like blinking), use a capacitor. For high-speed signals (like audio), use 3. Calculate Resistance ( Rearrange the formula to find
cap R equals the fraction with numerator 1.2 and denominator f center dot cap C end-fraction Example Calculation ) capacitor: 0.00000001
cap R equals the fraction with numerator 1.2 and denominator 10 comma 000 center dot 0.00000001 end-fraction equals 1.2 over 0.0001 end-fraction equals 12 comma 000 space cap omega (or 12 k cap omega ) ✅ Results Summary
The 74HC14 creates a square wave by cycling voltage between two set thresholds ( cap V sub cap T plus end-sub cap V sub cap T minus end-sub
). By adjusting the "bucket" size (capacitor) or the "hose" size (resistor), you control exactly how fast that heartbeat pulses. or a list of common RC pairs for specific audio frequencies? #1106 74HC14 Oscillator
The Story of the "Sweet Spot": A Tale of the 74HC14 Oscillator Calculator
Chapter 1: The Analog Struggle
It was a rainy Tuesday in the embedded systems lab. Lucas, a junior firmware engineer, was staring at a mess of wires on a breadboard. His task seemed simple: create a 2kHz clock signal to drive a legacy buzzer driver for a retro-computing restoration project.
He had grabbed a handful of components: a capacitor, a resistor, and a Schmidt Trigger Inverter chip—the famous 74HC14.
Lucas knew the basic formula from university textbooks: $f = 1 / (k \cdot R \cdot C)$. He plugged in values: a $100\textnF$ capacitor and a $4.7\textk\Omega$ resistor.
He connected the oscilloscope. Clipped. The frequency was reading $1.2\textkHz$. Too low.
He swapped the resistor for $2.2\textk\Omega$. Clipped. Now it was oscillating at $3.5\textkHz$. Too high.
Frustrated, Lucas realized the textbook formula had failed him. The "k" factor—the constant that accounts for the hysteresis of the Schmidt Trigger—wasn't a fixed number. It changed based on voltage, temperature, and the specific manufacturer of the chip. He needed a way to predict the behavior without spending all afternoon swapping components.
Chapter 2: The Mentor’s Intervention
Elena, the senior hardware architect, walked by, coffee in hand. She stopped and looked at Lucas’s chaotic desk.
"Let me guess," Elena said, pointing at the oscilloscope. "You're trying to hit a specific frequency using the 'hunt and peck' method with the 74HC14?"
"It shouldn't be this hard," Lucas sighed. "The math says one thing, the scope says another. The tolerance is all over the place."
Elena smiled. "The 74HC14 is a beautiful chip because it's robust, but it's not a precision oscillator. It's an RC relaxation oscillator. The math is an approximation. If you want to stop guessing, you need to build a calculator that respects the reality of the physics, not just the ideal formula."
She pulled up a chair. "Let's code a calculator. Not just a generic one, but one that tells you the safe operating range."
Chapter 3: Cracking the Math (The Backend)
They opened a Python IDE. Lucas started typing the standard formula: To build a 74HC14 relaxation oscillator , the
frequency = 1 / (R * C)
"Stop," Elena said. "That's for an ideal oscillator. The 74HC14 has hysteresis. The capacitor has to charge to the Upper Threshold ($V_T+$) and discharge to the Lower Threshold ($V_T-$). The standard approximation constant is roughly $0.8$, but the real constant $k$ is derived from the hysteresis ratio."
Elena explained the real formula they needed to program: $$f \approx \frac1R \times C \times \ln\left(\fracV_DD-V_T-V_DD-V_T+ \times \fracV_T+V_T-\right)$$
"The problem," Elena noted, "is that datasheets don't give you a fixed $V_T+$ or $V_T-$. They give you a range. For a 5V supply, $V_T+$ might be $3.0\textV$, or it might be $3.6\textV$. That variance completely changes your frequency."
The Calculator Logic: They decided the calculator needed three modes:
- Ideal Mode: Uses the standard $f = 1 / (0.8 \cdot RC)$ approximation.
- Datasheet Mode: Uses the min/max values from the NXP or Texas Instruments datasheet to calculate a "Best Case" and "Worst Case" frequency.
- Practical Mode: Allows the user to input their measured supply voltage and target frequency, outputting the standard resistor value
The 74HC14 is a hex Schmitt-trigger inverter that can be easily configured as an RC relaxation oscillator. Because of its built-in hysteresis—switching at different upper ( VT+cap V sub cap T plus end-sub ) and lower ( VT−cap V sub cap T minus end-sub ) threshold voltages—a single resistor ( ) and capacitor (
) are all that's needed to create a stable square-wave output. Oscillator Frequency Formula
The standard approximation for calculating the oscillation frequency ( ) of a 74HC14 circuit is:
f≈10.8⋅R⋅Cf is approximately equal to the fraction with numerator 1 and denominator 0.8 center dot cap R center dot cap C end-fraction
Alternatively, some simplified calculators use a constant of for specific supply voltages:
f≈1.2R⋅Cf is approximately equal to the fraction with numerator 1.2 and denominator cap R center dot cap C end-fraction : Frequency in Hertz (Hz) : Resistance in Ohms ( Ωcap omega : Capacitance in Farads (F). Step-by-Step Design Guide 74hc14 relaxation oscillator - NI Community
Understanding the 74HC14 Oscillator Calculator: A Comprehensive Guide
The 74HC14 is a popular integrated circuit (IC) used in a wide range of electronic applications, including oscillators. An oscillator is a crucial component in many electronic circuits, generating a stable frequency signal that is used to control other components or to transmit information. In this article, we will explore the 74HC14 oscillator calculator, a tool used to design and optimize oscillators using the 74HC14 IC.
What is the 74HC14 IC?
The 74HC14 is a hex inverting Schmitt trigger IC, which means it consists of six independent inverting Schmitt trigger circuits. A Schmitt trigger is a type of comparator circuit that produces a digital output signal based on an analog input signal. The 74HC14 IC is known for its high-speed operation, low power consumption, and wide operating voltage range.
How Does the 74HC14 Work as an Oscillator?
The 74HC14 IC can be used to create an oscillator circuit by connecting one or more of its Schmitt trigger circuits in a feedback loop. The oscillator circuit uses the hysteresis property of the Schmitt trigger to generate a stable oscillation. The hysteresis property allows the circuit to have two stable states, which are used to create the oscillation.
74HC14 Oscillator Calculator: What is it?
The 74HC14 oscillator calculator is a tool used to design and optimize oscillators using the 74HC14 IC. The calculator takes into account various parameters such as the desired frequency of oscillation, the supply voltage, and the external component values to calculate the required component values for the oscillator circuit.
How to Use the 74HC14 Oscillator Calculator?
Using the 74HC14 oscillator calculator is relatively straightforward. Here are the general steps:
- Determine the desired frequency of oscillation: Decide on the frequency of oscillation you want to achieve with your oscillator circuit.
- Choose the supply voltage: Select the supply voltage for your circuit, which is the voltage that will be applied to the 74HC14 IC.
- Select the external component values: Choose the values of the external components, such as resistors and capacitors, that will be used in the oscillator circuit.
- Enter the values into the calculator: Enter the desired frequency of oscillation, supply voltage, and external component values into the 74HC14 oscillator calculator.
- Calculate the component values: The calculator will then calculate the required component values for the oscillator circuit.
Parameters Considered by the 74HC14 Oscillator Calculator
The 74HC14 oscillator calculator takes into account various parameters to calculate the required component values for the oscillator circuit. These parameters include:
- Frequency of oscillation: The desired frequency of oscillation, typically specified in hertz (Hz).
- Supply voltage: The voltage applied to the 74HC14 IC, typically specified in volts (V).
- Capacitance: The value of the capacitor used in the oscillator circuit, typically specified in farads (F).
- Resistance: The value of the resistor used in the oscillator circuit, typically specified in ohms (Ω).
- Duty cycle: The desired duty cycle of the oscillation signal, typically specified as a percentage.
Types of 74HC14 Oscillator Circuits
There are several types of oscillator circuits that can be designed using the 74HC14 IC, including:
- RC oscillator: A simple oscillator circuit that uses a resistor and capacitor to generate the oscillation.
- Crystal oscillator: A more precise oscillator circuit that uses a crystal to generate the oscillation.
- LC oscillator: An oscillator circuit that uses an inductor and capacitor to generate the oscillation.
Advantages of Using the 74HC14 Oscillator Calculator
Using the 74HC14 oscillator calculator offers several advantages, including:
- Accurate calculations: The calculator provides accurate calculations of the required component values, reducing the need for trial and error.
- Time-saving: The calculator saves time and effort by automating the design process.
- Optimization: The calculator can be used to optimize the oscillator circuit for specific applications.
Common Applications of the 74HC14 Oscillator
The 74HC14 IC is widely used in various applications, including:
- Clock generation: The 74HC14 IC is used to generate clock signals in digital circuits.
- Frequency generation: The IC is used to generate stable frequencies in applications such as radio transmitters and receivers.
- Signal processing: The IC is used in signal processing applications, such as filtering and amplification.
Conclusion
In conclusion, the 74HC14 oscillator calculator is a useful tool for designing and optimizing oscillators using the 74HC14 IC. By understanding the parameters considered by the calculator and the types of oscillator circuits that can be designed, engineers and hobbyists can create stable and accurate oscillator circuits for a wide range of applications.
Example of 74HC14 Oscillator Calculator
Here is an example of a 74HC14 oscillator calculator:
| Frequency (Hz) | Supply Voltage (V) | Capacitance (F) | Resistance (Ω) | Duty Cycle (%) | | --- | --- | --- | --- | --- | | 1000 | 5 | 100nF | 10kΩ | 50 |
Using the calculator, the required component values for the oscillator circuit can be calculated as:
- R1: 10kΩ
- R2: 10kΩ
- C1: 100nF
- C2: 100nF
References
- 74HC14 datasheet: The official datasheet for the 74HC14 IC, which provides detailed specifications and application notes.
- Oscillator design guide: A comprehensive guide to designing oscillators using the 74HC14 IC.
By following the guidelines and using the 74HC14 oscillator calculator, engineers and hobbyists can create stable and accurate oscillator circuits for a wide range of applications.
Designing a Square Wave: The 74HC14 Oscillator Guide Building a basic square wave generator doesn't always require a 555 timer. The 74HC14 Hex Schmitt Trigger Inverter Go to product viewer dialog for this item.
is a simpler, more compact alternative for creating stable oscillators. Whether you are looking to blink an LED or generate an audio tone, here is everything you need to calculate and build your own. The Simple Circuit Setup
To turn a single gate of a 74HC14 into an oscillator, you only need two external components:
Resistor (R): Connected between the output (pin 2) and input (pin 1).
Capacitor (C): Connected from the input (pin 1) to Ground (GND).
Don't forget to connect VCC (pin 14) to your power supply (2V–6V) and GND (pin 7) to ground. The Frequency Formula The frequency of oscillation (
) depends on the time it takes the capacitor to charge and discharge between the chip's upper and lower switching thresholds.
While the exact formula involves natural logarithms of the threshold voltages, a commonly used rule-of-thumb approximation for the 74HC14 is:
f≈10.8⋅R⋅Cf is approximately equal to the fraction with numerator 1 and denominator 0.8 center dot cap R center dot cap C end-fraction
Note: For more precise design, some engineers use a divisor closer to depending on the specific supply voltage and chip brand. Example Calculation: If you use a 10kΩ resistor and a 0.1µF capacitor: Convert values: Calculate: Designing for Your Needs #1106 74HC14 Oscillator
is a Hex Inverting Schmitt Trigger that is commonly used to create a simple, low-cost RC Relaxation Oscillator
. Because it features hysteresis, you can generate a stable square wave using only a single resistor ( ) and a single capacitor ( The Oscillator Formula The frequency of oscillation (
) for a 74HC14-based circuit is generally determined by the following formula:
f is approximately equal to the fraction with numerator 1 and denominator k center dot cap R center dot cap C end-fraction is the frequency in Hertz (Hz). is the resistance in Ohms ( is the capacitance in Farads (F). is a constant, typically around
, depending on the specific manufacturer's hysteresis voltage levels and the supply voltage ( cap V sub cap C cap C end-sub 1. Understand the Schmitt Trigger Mechanism
The 74HC14 doesn't switch at exactly half of the supply voltage. Instead, it has two specific thresholds: Positive-going Threshold ( cap V sub cap T plus end-sub
The input voltage at which the output switches from HIGH to LOW. Negative-going Threshold ( cap V sub cap T minus end-sub
The input voltage at which the output switches from LOW to HIGH.
The "hysteresis" is the difference between these two points (
). The capacitor charges and discharges between these two specific levels, creating the timing interval. 2. Calculate the Period A more precise way to calculate the time period ( )—which is —is to account for the natural log of the voltage ratios:
cap T equals cap R center dot cap C center dot l n open paren the fraction with numerator cap V sub cap C cap C end-sub minus cap V sub cap T minus end-sub and denominator cap V sub cap C cap C end-sub minus cap V sub cap T plus end-sub end-fraction center dot the fraction with numerator cap V sub cap T plus end-sub and denominator cap V sub cap T minus end-sub end-fraction close paren For most 74HC14 chips running at , the thresholds are roughly . Plugging these in often results in a simplified constant 3. Account for Component Limitations
When designing your circuit, keep these practical constraints in mind: Resistor Range:
is too low, the output current might be too high; if it's too high, input leakage current will cause frequency drift. Capacitor Type:
Use high-quality film or ceramic capacitors. Avoid electrolytic capacitors for timing if possible, as their wide tolerances and leakage can make the frequency unpredictable. Supply Voltage: Changes in cap V sub cap C cap C end-sub will shift the cap V sub cap T plus end-sub cap V sub cap T minus end-sub points slightly, which in turn changes the frequency. 4. Visualize the Waveform The voltage across the capacitor ( cap V sub cap C
) will be a "shark-fin" or exponential triangle wave, while the output of the 74HC14 will be a clean square wave. Final Calculation Summary To find your frequency, use the simplified estimation:
f is approximately equal to the fraction with numerator 1.2 and denominator cap R center dot cap C end-fraction (Note: Using
as a constant is a common "rule of thumb" for the 74HC14 to account for typical propagation delays and threshold variances.)
The frequency of a 74HC14 oscillator is determined by the RC time constant and the internal hysteresis thresholds of the Schmitt trigger. for a target frequency?
Designing a 74HC14 Schmitt Trigger Oscillator The 74HC14 is a high-speed CMOS hex inverter with Schmitt-trigger inputs. It is one of the easiest ways to build a square-wave relaxation oscillator without needing a dedicated timer like the 555. How the Oscillator Works
A basic relaxation oscillator is created by connecting a single resistor ( ) and a capacitor ( ) to one of the 74HC14’s six gates:
Capacitor Charging: When the output is HIGH, the capacitor charges through the resistor until it reaches the upper threshold voltage ( VT+cap V sub cap T plus end-sub ) of the Schmitt trigger. Output Swaps: Once VT+cap V sub cap T plus end-sub is reached, the inverter output flips to LOW.
Capacitor Discharging: The capacitor then discharges through the same resistor until it hits the lower threshold voltage ( VT−cap V sub cap T minus end-sub ).
Repeat: The output flips HIGH again, and the cycle continues, generating a continuous square wave. The Frequency Calculation Formula
Because different manufacturers have slightly different hysteresis windows, the "exact" formula can vary. However, a widely accepted approximation for the 74HC14 is: Part 4: Practical Design Guidelines (Beyond the Calculator)
f≈10.8×R×Cf is approximately equal to the fraction with numerator 1 and denominator 0.8 cross cap R cross cap C end-fraction : Frequency in Hertz (Hz) : Resistance in Ohms ( Ωcap omega ) : Capacitance in Farads (F) Example Calculation:If you use a resistor and a capacitor: (12.5 kHz) 7414 Oscillator Calculator - Learning about Electronics
Here’s a concise review of “74HC14 oscillator calculator” tools (typically web-based or spreadsheet calculators for RC oscillators using the 74HC14 Schmitt-trigger inverter).