multimeter பயன்படுத்துவது எப்படி
How to measure ac voltageDigital multimeters
Steps for measuring AC voltage with a digital multimeter
Turn the dial to ṽ. Some digital multimeters (DMMs) also include m ṽ . If voltage in the circuit is unknown, set the range to the highest voltage setting and set the dial on ṽ.
Note: Most multimeters power up in Autorange mode. This automatically selects a measurement range based on voltage present.First insert the black lead into the COM jack.Next insert the red lead into the VΩ jack. When finished, remove the leads in reverse order: red first, then black.Connect the test leads to the circuit: black lead first, red second.
Note: ac voltage does not have polarity.
How to measure dc voltage with a digital multimeter
Digital multimeters
Turn dial to dc voltage. Some digital multimeters (DMMs) also include dc millivolts. If uncertain of which to choose, start with dc voltage, which handles higher voltage.
First insert the black probe into the COM jack.
Steps for measuring dc voltage with a digital multimeter
Steps for measuring dc voltage with a digital multimeter
Then insert the red probes into the V Ω jack. When finished, remove the probes in reverse order: red first, then black.
Connect the test probes to the circuit: black to the negative polarity test point (circuit ground), red to positive test point.
Note: Most modern multimeters automatically detect polarity. When measuring dc voltage, it is not critical for the red lead to contact a positive terminal or black to touch negative. Just recognize if the probes touch opposite terminals, a negative symbol will appear in the display. With an analog multimeter, red leads should always touch a positive terminal and black a negative terminal. Otherwise, damage to the meter will occur.
Read the measurement in the display.How to measure dc voltage with a digital multimeterDigital multimeters
Turn dial to dc voltage. Some digital multimeters (DMMs) also include dc millivolts. If uncertain of which to choose, start with dc voltage, which handles higher voltage.First insert the black probe into the COM jack.
To measure resistance:
1. Turn power to circuit OFF.
If a circuit includes a capacitor, discharge the capacitor before taking any resistance reading.
2. Turn digital multimeter dial to resistance, or ohms, which often shares a spot on the dial with one or more other test/measurement modes (continuity, capacitance or diode; see illustration below).
The display should show OLΩ because, in Resistance mode, even before test leads are connected to a component, a digital multimeter automatically begins taking a resistance measurement.
3. First insert the black test lead into the COM jack.
4. Then insert the red lead into the VΩ jack.
When finished, remove the leads in reverse order: red first, then black.
5. Connect test leads across the component being tested.
Make sure that contact between the test leads and circuit is good.
Tip: For very low-resistance measurements, use the relative mode (REL; see point 11). It may also be referred to as zero or Delta (Δ) mode. It automatically subtracts test lead resistance-typically 0.2 Ω to 0.5 Ω. Ideally, if test leads touch (are shorted together), the display should show 0 Ω.
Other factors that can affect resistance readings: Foreign substances (dirt, solder flux, oil), body contact with the metal ends of the test leads, or parallel circuit paths. The human body becomes a parallel resistance path, lowering total circuit resistance. Thus, avoid touching metal parts of test leads to avoid errors.
6. Read the measurement on the display.
7. When finished, turn the multimeter OFF to prevent battery drain.
Advanced digital multimeter options
8. Press the RANGE button to select a specific fixed measurement range.
Be sure to note the annunciator (such as K or M) after the measurement in the display.
9. Press the HOLD button to capture a stable measurement-it can be viewed later.
10. Press the MIN/MAX button to capture the lowest and highest measurement.
The multimeter beeps each time a new reading is recorded.
11. Press the relative (REL) button to set the multimeter to a specific reference value.
Measurements above and below the reference value
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