Buzz
Testing LED lights with a digital multimeter is a simple process. The clear readings from the measurements will show the brightness of each bulb. The brightness of the LED during testing also indicates its quality. If you don’t have a multimeter, you can use a coin cell battery holder with wires to check if the LED is still functional.
Steps
Using a Multimeter
Purchase a digital multimeter with a diode testing feature. Basic multimeters can only measure amps, volts, and ohms. To test LEDs, you need a multimeter with a diode setting. Since this feature is often absent in low-end models, consider mid-range to high-end options available online or at local electronics stores.
- A good-quality mid-range multimeter typically costs between 1,000,000 - 2,500,000 VND.
- Opt for a digital multimeter over analog models, as analog displays can be harder to read and less accurate.
Connect the black and red probes. The black and red probes need to be connected to the ports located on the front of the multimeter. The red wire is used to measure the anode. The black wire should be plugged into the "COM" port and is used to connect to the cathode.
Turn the multimeter dial to the diode mode. Rotate the dial on the top of the multimeter clockwise from the "off" position. Continue turning until the arrow points to the diode setting. If not clearly marked, this setting may be represented by a diode circuit symbol.
- The diode symbol includes an icon representing both the anode (positive) and cathode (negative) of the circuit.
Connect the black probe to the cathode and the red probe to the anode. Touch the black probe to the cathode of the LED (usually the shorter leg). Next, connect the red probe to the anode, which has the longer leg. Ensure the black probe is connected first, followed by the red one, as reversing the order will yield incorrect readings.
- Make sure the cathode and anode do not touch during the measurement to ensure the current flows through the LED and provides accurate results.
- The red and black probes should not touch each other during the test.
- If connected correctly, the LED will light up.
Check the value on the multimeter's digital display. When the probes touch the cathode and anode, a functional LED will display a reading of approximately 1600 mV. If no reading appears, repeat the measurement to ensure proper connections. If done correctly and no reading is shown, the LED is likely damaged.
Evaluate the brightness of the LED. When tested correctly, the LED will light up. Record the reading on the digital display and observe the LED. If the reading is normal but the light appears dim, it may indicate a low-quality LED. High-performance LEDs emit bright, vibrant light.
Testing with a Coin Cell Battery
Use a coin cell battery to safely test the LED without risking damage. Coin cell batteries are the safest option because their voltage is low enough to prevent harm. Other types of batteries may burn out the LED. Coin cell batteries are available at pharmacies, grocery stores, electronics shops, or online.
- You can use CR2032 or CR2025 coin cell batteries.
Purchase a coin cell battery holder with appropriate wires. Buy a holder with wires designed for the type of coin cell battery you plan to use (e.g., CR2025). These holders can be found online or at electronics/hardware stores.
- Coin cell battery holders are often used for small projects like LED-integrated jewelry or clothing.
Connect the black probe to the cathode and the red probe to the anode of the LED. To test the LED, touch the black probe to the cathode or the shorter leg of the LED. Then, connect the red probe to the anode, which has the longer leg. Ensure the probes do not touch each other during the test, and the anode and cathode of the LED should also not touch.
- Some battery holders come with small connectors at the end of the wires.
- If the holder has connectors, insert the anode and cathode of the LED into the small holes aligned with the red and black wires.
Observe the LED. If the LED is functioning correctly and the connections are made properly, the LED will light up. If not, try swapping the positions of the anode and cathode and reconnect. If the LED still doesn’t light, it is likely damaged or faulty.
- If the LED doesn’t light up, test other LEDs immediately afterward. If the subsequent LEDs light up normally, you can confirm that the first LED is non-functional.
