Arduino
Heart rate monitor: counting beats in a very noisy signal
A finger-clip pulse sensor and the peak detection that turns a wobbly waveform into a BPM number. Why pressing harder makes it worse, why a moving threshold beats...
Arduino
LPG gas leak alarm that you can actually trust
A kitchen gas alarm for about Rs.900. Why the sensor needs 24 hours of burn-in before you believe it, why the datasheet number is not a PPM reading,...
Beginner
Self-watering planter that texts you when the tank runs dry
Keeps a plant alive while you are away, and tells you before it fails. Why the cheap resistive moisture probes corrode away in weeks, why a dry-run protection...
Arduino
Sound-reactive LED matrix: making a WS2812 panel dance to music
A 16-pixel RGB panel that pulses with whatever is playing, for about Rs.350. Why a sound sensor does not measure loudness the way you expect, the auto-gain trick...
