# How much power can reasonably be collected from ambient background radiation?

It seems that with a coil or simple antenna it should be possible to collect energy from the background 60Hz radiation in any modern home. How much could reasonably collected at low voltages (3.3-5V)? Could it be enough to maintain a sleeping microcontroller (e.g. 1uA - 100uA @ 3.3V?)

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The answer is "very little". I have also seen 10s of volts on a 1 MΩ scope probe when I touched it. However, the scope can only see that voltage because it has a explicit ground reference. The basic problem is that it will be very hard to get a large enough differential power pickup.

All voltages are effectively differential. It worked for the scope only because it was implicitly using the ground plug as the other connection it was comparing the probe tip voltage to. Getting a meaningful differential voltage from a small box is a much harder problem. To get any differential voltage at all by capacitive coupling, you need a E field gradient. That absolute value of the E field does not matter.

My knee jerk reaction therefore is that no, you won't be able to harvest enough power in a small box from stray power line fields in your house to run a microcontroller.