On a microcontroller, though, you’ll have to roll your own CPU load meter with a few parts, some code, and a voltmeter. We like [Dave Marples]’s simple approach to quantifying something as ...

That makes it a perfect tool for working with radios in the HF range. The project is relatively simple to construct, with an STM32F103C6 or C8 development board used as the brains of the operation.

They’re called power meters, and they’re fairly inexpensive. USB power meters are pretty simple. You plug them into your device and they act as a conduit between it, the charging cable and the power ...