as Joachim mentioned; and as i thought i replied already - all sensors have enough noise to be entropy sources. If you can quiesce a sensor - by putting it in a

as Joachim mentioned; and as i thought i replied already - all sensors have enough noise to be entropy sources. If you can quiesce a sensor - by putting it in a chamber that reduces whatever it senses, or otherwise reducing the input, you can grab "noise". MEMS sensors are notorious for being "noisy", and should always be looked at for cheap entropy sources. Followed by webcams in black chambers, webcams with a single photon source in a reflective chamber, anything that can pick up any RF whatsoever (including ADCs with signal and a resistor or inductor to ground), and so on up to thermals, Geiger detectors, avalanche silicon circuits, and beyond.