Enter your Resistor R1, Resistor R2, and Capacitor C values (with their units) into the Relaxation Oscillator Calculator, and it'll calculate your circuit's oscillation frequency, period, RC time constant, and duty cycle — or flip to Target Frequency mode to work backwards from a desired frequency.
Oscillation Frequency
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Period
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RC Time Constant
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Duty Cycle
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A relaxation oscillator is a circuit that generates a square wave output using an op-amp, resistors, and a capacitor. It works by repeatedly charging and discharging the capacitor through the RC network, causing the op-amp output to switch between high and low states.
The frequency is approximately f = 1/(2.2 × R × C) for a standard relaxation oscillator, where R is the timing resistance and C is the capacitor value. The exact formula depends on the specific circuit configuration and component values.
The primary factors are the resistance and capacitance values in the timing circuit. Temperature can also affect component values slightly, and the op-amp's slew rate may limit maximum frequency in some cases.
Yes, by using different resistor values for the charging and discharging paths, you can create asymmetric square waves with custom duty cycles. Adding diodes in parallel with resistors is a common method to achieve this.
Relaxation oscillators are used in timing circuits, clock generators, pulse generators, LED flashers, and as simple square wave sources for digital circuits. They're popular because of their simplicity and reliability.
Standard resistors have 5% tolerance and capacitors can vary by 10-20%. For precise frequency control, use 1% resistors and stable capacitor types like film capacitors rather than electrolytic ones.
Low frequencies are limited by capacitor leakage and can go down to millihertz. High frequencies are limited by the op-amp's slew rate and bandwidth, typically up to several hundred kHz for general-purpose op-amps.
Start with a desired capacitor value (typically 1nF to 100µF), then calculate the required resistance using R = 1/(2.2 × f × C). Choose the nearest standard resistor value and fine-tune if needed.