If you want the most accurate resistance measurement possible, you’ll want to take a 4-wire resistance measurement. Then probe the desired area of the circuit.
Ensure the circuit or device under test is powered off. To take a 2-wire resistance measurement with a benchtop multimeter, select the “ohm” or “Ω” mode, and connect the probes to the “INPUT HI” and “INPUT LO” ports. For a 2-wire measurement, the injected current and the observed voltage are both done through the same probes. This is a simpler measurement to make and the probes are less complicated and expensive. If you’re not worried about the added resistance of the probe wires, taking a 2-wire resistance measurement will be sufficient. For this reason, there are two different modes for measuring resistance: 2-wire mode and 4-wire mode. Since even wires have resistance, the wires of the probes can actually add to the observed resistance measurement. The known current, and the resulting voltage drop are then used to calculate the resistance using Ohm’s Law, V=I^2*R. Multimeters measure resistance by injecting a small current into the circuit, and then measuring the voltage drop across those points in the circuit. Measuring resistance with a multimeter can be done a couple of different ways, depending on the level of accuracy needed in the measurement. Apply power to the circuit or device under test and probe points on circuit The positive probe should be connected to the “INPUT HI” port, while the negative probe should be connected to the “INPUT LO” port. To measure AC voltage using a benchtop multimeter, select the “AC V” mode and connect your probes. Measuring AC voltage is almost identical to measuring DC voltage, however this mode is used for measuring the voltage potential between two points of an AC or “alternating current” circuit. Apply power to the circuit or device under test and probe points on circuit. To measure DC voltage using a benchtop multimeter, once you've turned it on, select “DC V” mode.Ĭonnect your probes to your multimeter the positive probe should be connected to the “INPUT HI” port, while the negative probe should be connected to the “INPUT LO” port. That difference in potential is measured in units of. The DC voltage measurement is used to determine the difference in electrical potential between two points in a DC or “direct current” circuit. Let's start with DC voltage, one of the simplest and most-used multimeter measurements. For this purpose of this article, we’ll assume a benchtop multimeter is being used. Benchtop multimeters tend to offer higher precision than their smaller handheld counterparts. Multimeters can be both handheld or benchtop units.
This includes measurements like voltage, current, resistance, etc. Multimeters are used for taking basic electrical measurements related to Ohm’s Law. Reprinted with permission from Evaluation EngineeringĪ multimeter or digital multimeter (DMM) is one of the most essential and common pieces of lab equipment.
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