Master the Basics: How to Measure DC Voltage with a Multimeter
One of the most common tasks when working with electronics is measuring voltage, and a digital multimeter (DMM) makes this process quick and easy. In this post, we'll walk you through how to measure DC voltage, which is the type of voltage you’ll find in battery-powered circuits.
Step 1: Set Up Your Multimeter
Plug the black probe into the COM (common) port.
Plug the red probe into the V port, usually marked with a "V" or "VΩmA".
Then, turn the dial on your multimeter to the DC voltage setting. Look for the symbol “V” with a straight line above a dashed line, or the label “VDC.” This is different from AC voltage, which is used for measuring wall power and is labeled “VAC” or “V~.”
If your multimeter has auto-ranging, it will choose the best range automatically. If not, you’ll need to set it manually.
Step 2: Select the Right Voltage Range
If you’re not sure what voltage to expect, start with the lowest range and increase it until you get a readable value. For example, if you’re measuring a 9V battery, choose the 20V range for best accuracy.
If the voltage is too high for the selected range, you may see an error like “1” or “OL.” If the range is too high, the value will show but with less detail.
Step 3: Connect Your Probes
To measure voltage between two points:
- Connect the black probe to your ground or reference point.
- Touch the red probe to the point you want to measure.
For example, measuring across a 9V battery should show a little more than 9 volts. If you reverse the probes, the display will show a negative value instead.
Step 4: Measure Voltage Across Components
Let’s say you have a simple circuit with a battery, a resistor, and an LED.
- If you measure across the battery, you’ll get around 9V.
- If you measure across the LED, you’ll see about 2V, which is normal for many LEDs.
Step 5: Use the Same Method in Complex Circuits
Even in more complex circuits, the approach is the same. Connect the black probe to ground and move the red probe around to different points. This lets you understand how voltage behaves across your circuit.
Key Takeways
Measuring DC voltage with a multimeter is one of the first and most important skills to learn in electronics. With just a few simple steps, you can begin troubleshooting, analyzing, and understanding your circuits with confidence.
