Electronic – How to measure the current flow to a component


I'm building a hexapod robot using simple servos and I was wondering how feasible it was to measure the current flow to each servo (5-6V DC to a maximum of 0.25-1A (I haven't found the spec for the servo's stall current yet)) using, say, an ATMega168. What kind of circuit would I need to build in series with each of the servo's power lines to give me a useful readout? I assume I'd get a voltage drop across this circuit, what's it likely to be? etc.

Best Answer

Honestly, People often use a simple sense resistor.

You place an in series very low resistance resistor(<1 ohm often) and you measure voltage drop. This allows you to monitor motor current.

There are many many motor control algorithms if you want to control the motor yourself, otherwise, if you are measuring for just knowing current draw, you just need to make sure you sample often enough to get an accurate measurement, or use a circuit with a lowpass filter effect(make sure you buffer the voltage).