Quote:
Originally Posted by Tubejunke
You can't measure current (Amperes) with a volt meter. And it is essential to remember that current measurements must always be taken with the meter in series with the circuit to be measured , not "across" it or in parallel. Probably just a type-o, but I saw the statement and thought that it would be worth noting and possibly saving your meter.
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Wrong. You CAN measure current indirectly with volt meter. Old coot's post does a good job of explaining that if you measure the voltage drop across a resistor of known value and use Ohm's law (I=E/R) you can compute the current flowing through that resistor quite accurately.
In fact most modern Digital Multi-Meters (DMMs) use that principle. In my freshman year of college I built a digital multimeter kit and it used that exact principle. It had a short length of thick wire shorting the + and - current measurement terminals and we had to adjust the length of wire that we soldered between those terminals so that it was exactly 1 Ohm. At that value 2A through it meant 2V across it, 1A -> a 1V drop and so on. The circuit simply measured the voltage drop across that wire that shorted the current measurement terminals and scaled the value according to the range it was set to.