| Oscillator | Inputs | Approx. Frequency | Notes |
|---|---|---|---|
| Wien bridge | R = 10 kΩ, C = 10 nF | ≈ 1.59 kHz | Equal components for clean sine output. |
| RC phase shift | R = 10 kΩ, C = 10 nF | ≈ 649 Hz | Three RC sections in series. |
| 555 astable | RA = 10 kΩ, RB = 10 kΩ, C = 10 nF | ≈ 4.80 kHz | Square wave; duty cycle depends on resistors. |
1) Wien bridge (equal components)
f = 1 / (2πRC)
A common design target is amplifier gain near 3 to sustain oscillation.
2) Wien bridge (custom R1,R2,C1,C2)
f = 1 / (2π √(R1·R2·C1·C2))
For zero phase shift at resonance, the ratio condition R2/R1 = C1/C2 is typically used.
3) RC phase shift oscillator (3 sections)
f = 1 / (2πRC √6)
This is the standard approximation for three identical RC sections.
4) RC relaxation oscillator (555 astable)
f = 1.44 / ((RA + 2RB)C)
tHigh = 0.693(RA + RB)C, tLow = 0.693(RB)C
This mode produces a square wave rather than a sine wave.
- Select the oscillator type that matches your circuit.
- Enter resistor and capacitor values with correct units.
- For custom Wien bridge, fill R1, R2, C1, and C2.
- Press Calculate to show results above the form.
- Use Download CSV or Download PDF to save output.
- Adjust component values to meet your target frequency range.
1) Why RC oscillators matter
RC oscillators create periodic signals using resistor–capacitor timing networks. They are widely used for test tones, sensor excitation, clocks for simple control circuits, and educational labs. Their frequency depends strongly on component values, making them easy to tune and analyze.
2) Frequency range and practical limits
Most RC designs operate from sub‑hertz up to a few megahertz. At higher frequencies, parasitic capacitance, amplifier bandwidth, and layout effects shift the expected value. For audio work, 10 Hz to 20 kHz is common; for timing, 0.1 Hz to 100 kHz is typical.
3) Wien bridge behavior and data points
The Wien bridge produces low‑distortion sine waves when the amplitude is stabilized. With equal components, R = 10 kΩ and C = 10 nF yields about 1.59 kHz. Doubling R halves the frequency; doubling C also halves the frequency. This linear scaling helps rapid design iteration.
4) Custom Wien networks for fine control
Using R1, R2, C1, and C2 allows you to hit target frequencies with available parts. A helpful design condition is matching ratios so the phase shift is near zero at the oscillation point. This reduces startup issues and keeps the waveform stable under load changes.
5) RC phase shift oscillator characteristics
The three‑section phase shift topology is simple and uses identical RC stages. With R = 10 kΩ and C = 10 nF, the frequency is roughly 649 Hz. Because the feedback network attenuates the signal, the amplifier must provide higher gain than a Wien design.
6) 555 astable timing and duty cycle
The 555 astable is a relaxation oscillator that outputs a square wave. For RA = 10 kΩ, RB = 10 kΩ, and C = 10 nF, frequency is around 4.80 kHz with a duty cycle near 66.7%. Increasing RB increases both period and low time.
7) Tolerances, drift, and measurement
Frequency accuracy is limited by resistor and capacitor tolerances. A 5% resistor and 10% capacitor can produce about ±15% combined variation. Temperature coefficients and aging can add drift, especially with electrolytics. For best stability, prefer film capacitors and 1% resistors.
8) Design workflow using this calculator
Start by selecting the oscillator type, then enter candidate values with units. Compare frequency and period outputs and adjust values to meet your target. For square‑wave timing, review high/low times and duty cycle. Finally, export CSV or PDF for lab records.
1) Which oscillator type should I choose?
Choose Wien bridge for clean sine waves, phase shift for a minimal parts sine source, and 555 astable for square‑wave timing. Match the option to your waveform and frequency goals.
2) Why does the calculator show frequency and period?
Frequency is convenient for design targets, while period is useful for timing tasks and oscilloscope checks. Both are reciprocals, so you can validate results quickly during prototyping.
3) What unit mistakes are most common?
Mixing µF with nF and kΩ with Ω causes large errors. Always confirm the unit dropdowns match the component markings, especially when switching between audio and high‑frequency designs.
4) How accurate are the formulas?
They are standard approximations for ideal components. Real circuits may deviate due to amplifier bandwidth, loading, and parasitics. Use the results as a starting point and verify with measurement.
5) How do tolerances affect my final frequency?
Frequency depends on products like RC or √(R1R2C1C2). Part tolerances combine, so a few percent on each part can become a noticeable shift. Use tighter tolerance parts for precision.
6) Why does the 555 duty cycle change with RA and RB?
In the common astable configuration, the capacitor charges through RA+RB and discharges through RB. That makes the high time depend on both resistors and the low time depend mostly on RB.
7) Can I use this for quick lab documentation?
Yes. Calculate with your measured component values, then export CSV or PDF. This creates a repeatable record of assumptions and results that you can attach to reports or notebooks.