USB Current Meter

…or USB power meter?
…or USB KEY AVR Tiny split core interface?

Call it however you want, this project is a small USB key sized circuit to interface an USB system with a single split core current sensor using an ATtiny85.

These non-invasive sensors are widely available on eBay and similar for a reasonable price (around USD$ 30 for the one I used) and let you measure the current flowing through an alternate voltage line, like house mains. This can be used to get a gross measure of instantaneous power consumption, allowing you to make a graph out of it and plot your power usage profile, or just to check how much power a device is using.

A friend of mine is using this one side-by-side with its photovoltaic inverter to upload his data on pvoutput.org, a nice website for photovoltaic plant monitoring.

This also shows a rectifier circuit to acquire data from an alternate voltage source without dual power rails.

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