By Jacob Andrew, Updated March 24, 2022
An analog multimeter delivers precise measurements of voltage, resistance, and current through a simple dial and needle. By connecting its red and black probes to the circuit’s positive and negative terminals, you can quickly identify where a fault lies—whether in an appliance, wiring, or a more complex system.
Attach the red probe to the "+" terminal and the black probe to the "-" terminal of the multimeter.
Rotate the function dial to the desired parameter: voltage (V), resistance (Ω), or current (A). Each setting activates a different internal circuit within the meter to provide an accurate reading.
To measure voltage, place the red probe near the positive end of the live circuit and the black probe downstream. The needle will indicate the voltage present when the probes touch.
For resistance, touch the red probe to one side of the component and the black probe to the opposite side. A needle that points to zero Ω means no resistance, while a needle that reaches the far end of the dial indicates infinite resistance. Ensure the ohmmeter is set to the correct range (see Tips) to avoid misreading.
Measuring current requires the multimeter to be inserted in series with the circuit. Some analog meters need the red probe moved to a jack labeled "A" or "amps." Connect the circuit’s positive lead to the red probe, then the black probe to the device’s positive terminal. The needle will show the maximum current that can flow.
Resistance scales are typically marked in increments such as 1,000; 100; 10; .001 Ω. Set the ohmmeter to a range that encompasses the expected value—for example, a 400 Ω resistor should be tested on the 100 Ω range, where the needle will read “4.” Setting the scale too low (e.g., .001 Ω) will cause the needle to over‑travel, giving a false “no‑conductance” reading. Always check the battery (usually 9 V) if the meter reads zero on all resistances. Analog meters also contain a fuse that protects against overload; a blown fuse will display high or infinite resistance. Test it by setting the meter to the highest range and shorting the probes together—zero or near‑zero resistance indicates a good fuse, whereas a high reading means the fuse has blown and should be replaced.
Working with electricity poses serious risks, especially when measuring current. Anything exceeding 200 mA (0.002 A) can induce ventricular fibrillation. Household outlets commonly supply at least 10 A (10,000 mA). Always turn off the circuit before connecting the meter, and only energize it when ready to test. If you are uncertain about any step—particularly when dealing with high voltage or current—seek assistance from a qualified professional.
