How does the duty cycle change the sound?

It changes which harmonics are present and how strong each one is. At fifty percent only odd multiples of the fundamental exist; as the duty moves away from that, even harmonics appear and the balance of the whole series shifts, which is heard as a change from hollow and square-like to thin and nasal.

Why is the default twenty five percent rather than fifty?

Because the pulse shape exists to offer something a square cannot. A twenty five percent duty is the classic narrow pulse, noticeably thinner and more nasal than a square, and it makes the character of the control immediately obvious before you start adjusting it.

What happens at the extremes of the duty range?

The waveform spends nearly all its time at one level and the transitions dominate what is heard, so the tone becomes thin and buzzy and its energy concentrates in the edges. The range is capped at five and ninety five percent to keep the shape recognisable.

Does the fundamental stay at the frequency I set?

Yes, the repetition rate is exactly the frequency you entered. What changes with the duty is the relative level of the fundamental compared with its harmonics, so the perceived pitch holds steady while the brightness moves around it.

Can the duty cycle be swept during the file?

No, the value is fixed for the whole generation. To hear a sweep of character you would need to generate several files at different duties and join them, or use the chirp or sweep tools if it is the pitch rather than the timbre that should move.

Pulse Wave Generator

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Pulse Wave Generator produces a rectangular waveform whose high portion can occupy anywhere from five to ninety five percent of each cycle. Changing that duty cycle changes the tone without changing the pitch.

What is Pulse Wave Generator?

Set the frequency, the duty cycle, the duration and the level, and press generate. The shape switches between two fixed levels, with the high portion lasting for the fraction of the cycle you chose and the low portion taking the rest.

The controls and what they do:

Frequency from one hundredth of a hertz to twenty thousand, defaulting to 100 hertz.
A duty cycle slider from five to ninety five percent, defaulting to twenty five, which sets how much of each cycle is spent at the high level.
Duration from a tenth of a second to sixty seconds, defaulting to three.
An amplitude slider from one to one hundred percent, defaulting to fifty.
A sample rate selector covering 44.1 and 48 kilohertz.

The duty cycle is the feature that distinguishes this tool from the square wave generator, and its effect on the spectrum is worth understanding rather than guessing at. At exactly fifty percent the shape is a square and only odd harmonics are present. Moving the duty away from fifty percent introduces even harmonics and rebalances the whole series: some partials grow, others shrink, and the fundamental's own level shifts. This is the same mechanism that gave early analogue and digital instruments their range of hollow, nasal and thin tones from a single oscillator, since the duty could be swept to move the harmonic balance while the pitch stayed put. Two consequences follow from the rectangular shape. The transitions are instantaneous, so the ideal form contains unbounded high-frequency content and, with no band-limiting applied, high fundamentals alias. And at very small or very large duties the waveform spends almost all its time at one level, which raises the energy in the transient edges relative to the steady state and produces the thin, buzzy quality that extremes are known for. A pulse wave is also the shape behind a great many classic synthesiser tones, since moving the duty while a note is held adds movement to a sustained sound without retuning it, and that is precisely the control this tool exposes. The rectangular form keeps its two levels fixed, so the pitch never wavers as the duty changes around it.

What to keep in mind:

There is no band-limiting, so high fundamentals alias as described.
Duty is limited to the five to ninety five percent range, and the tool does not offer to sweep it automatically over the file.
The waveform starts at the high level every time, so the file begins with a step.
No filter is available to shape the harmonic balance afterwards.
Amplitude is linear, not in decibels, so a precise level needs converting.
Output is mono and capped at sixty seconds.

Use it when the tone's character needs to be adjustable without touching the pitch: dialling in a hollow lead or bass tone, producing a distinctive test signal, or checking how a system handles a narrow pulse. When exactly fifty percent is all that is required, the square wave generator presents the same shape with fewer controls.

How to use Pulse Wave Generator

Set the frequency for the pitch you want.
Move the duty cycle slider to adjust the harmonic balance, listening as it changes.
Choose the duration and amplitude, then pick a sample rate.
Press generate and download the file once the tone sounds right.

When to use Pulse Wave Generator vs related tools

Pulse Wave Generator is the tool when the harmonic character of a rectangular wave needs to be adjustable while the pitch stays fixed. Square Wave Generator is the simpler fixed-duty case, and Tone Generator includes a pulse shape alongside the other four waveforms. When a brighter, non-adjustable spectrum is wanted, Sawtooth Wave Generator is the natural alternative.

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