Instrument 02 / seconds
Pulse Clock
Move the tempo slider or tap the button several times. Each interval sends light through the arterial branches. The default 72 BPM rhythm is illustrative.
Adjusting the rhythm restarts the beat count. Optional vibration begins only after you turn it on.
What this does not measure
This page generates a tempo chosen with a slider or taps. It does not sense or display your actual pulse, heart rate, circulation, or health. The chosen rhythm remains in this browser session and is not sent anywhere.
Why this clock exists
NIST defines frequency as the rate of a repeating event and period as the duration of one cycle; each is the reciprocal of the other. This clock shows that relationship in familiar tempo units, turning beats per minute into milliseconds per beat. The arterial drawing supplies a bodily metaphor, but the numbers come only from a visitor's slider or taps, never from a sensor.
NIST glossary of frequency