Josh from imsolidstate built this circuit to answer the age old question,
how much electric current does a truck really use? Actually, he was having trouble with the alternator (electricity generator) on his vehicle, and wasn’t sure if he should replace it with a regular one or a high output version, to help power his horse trailer. To figure out what to use, he built this current measuring circuit, which uses a hall effect sensor to measure the current coming from his alternator. After installing it in his vehicle, he used the system to measure how much current was drawn in a variety of situations. Since the trailer didn’t appear to draw much power, I can assume he went with a standard alternator. Schematics and source code are available on his website.

I’m guessing that most people don’t have a huge need to monitor their alternator like this, however the circuit can be used anywhere you need to measure current. I could see it coming in handy when designing a battery-powered robot or benchtop cnc machine. [via embedds]