How to measure the voltage of LED lamp beads
1. The voltage of LED lamp beads is not a constant value, similar to diodes. When the voltage increases, the current increases accordingly. For example, an ordinary LED starts to turn on at about 8V, and the current is about in the 1mA. It will increase sharply above 85. It can reach about 50-100mA at 3V.
2, a relatively simple method is through the light color, that is, the color of led lamp beads to distinguish how many volts led lamp beads are. For example, red led light beads are usually 8-4 volts. For example, yellow, orange and yellow-green led light beads are generally 8-4 volts.
3. Set the multimeter to the position marked with the diode, and then use the meter pen to connect the two pins of the LED lamp beads respectively. When there is a digital display, the pin measured by the red meter pen is positive. If the lamp bead is red, usually this state will be lit.
4. The power supply of the multimeter is 9V battery, but the output voltage is not that high at all. The LED can be measured with a diode gear, and the output voltage is a little more than two volts, which can make the lamp beads slightly bright.
How does the Led driver use the multimeter to measure no-load voltage?
When measuring the power supply voltage, modulate the multimeter to the voltage gear (distinguish DC from AC). Connect the positive pole of the black meter to the negative pole of the power supply in the red meter. The current measurement modulates the meter to the current gear (distinguishing AC and DC), the multimeter is connected in series to the input of the power supply, the red meter is connected to the positive pole of the power supply, and the black meter is connected to the positive pole of the LED power supply.
The no-load voltage can be measured directly with a multimeter. The no-load current needs to be converted. The total input power of the power supply is measured first, multiplied by a coefficient of 0.8, and then divided by the no-load voltage to get the no-load current value.
The voltage of non-isolated LED power supply under no-load condition is about 300V tested by multimeter and about 220V with current-by-current PFC. The isolated LED power supply, the voltage in the no-load state is tested with a multimeter, and the total voltage is about 3-5V more than the rated number of LED series.
Use the voltage of the multimeter at the input and output of the power supply to measure it. Can only simply measure whether there is a voltage, how many volts.
Because the resistance test voltage of some pointer multimeters is too low to light the LED, if the resistor range cannot light the LED, you can try to connect a dry cell in series and test again.
Power supply with 5V~6V voltage, a series of 100 ohms resistor, connected to both ends of the LED lamp, and then use the multimeter 20V voltage range to measure the voltage at both ends of the LED lamp, this voltage is the lighting voltage of the LED lamp.
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How to test led lamp beads with multimeter
1. A, use a universal red pen to connect the positive contact of the LED lamp bead, and use a universal meter black pen to connect the negative contact. When the LED lamp bead has a small brightness, it is good, otherwise it may be bad.
2. Observe the appearance of led lamp beads and determine the cathode and anode of the lamp beads. Adjust the gear of the multimeter to the transistor position. Connect the universal red pen to the anode and the black pen to the cathode. If the light is on, it means that the lamp bead is good.
3. Set the multimeter to the position marked with the diode, and then use the meter pen to connect the two pins of the LED lamp beads respectively. When there is a digital display, the pin measured by the red meter pen is positive. If the lamp bead is red, usually this state will be lit.
4. The multimeter measures the quality of LED lamp beads in the following ways: 1, the multimeter chooses the diode file, the red meter pen connects the lamp bead anode, the black meter pen connects the lamp bead cathode, if the lamp bead is slightly bright, it is good, otherwise it is bad. 2, the multimeter selects * 10k resistance file, the red meter pen connects with the lamp bead anode, the black meter pen connects with the cathode, the lamp bead is slightly bright is good.
5. Light-emitting diodes emit light in a variety of colors, such as red, green, yellow, etc., with circular and rectangular shapes. When light-emitting diodes leave the factory, one lead is longer than the other. Usually, the longer lead represents the anode and the other is the cathode. The low resistance gear of the multimeter cannot be measured. It can be tested with RX10K file.
LED Power supply Test how to use Multimeter to measure Voltage and current
1. The multimeter can only measure voltage. Use the voltage of the multimeter at the input and output of the power supply to measure it. Can only simply measure whether there is a voltage, how many volts.
2. The pointer multimeter is placed in the resistance R × 1k or R × 10k range, the black meter pen is connected to the positive pole of LED, and the red meter pen is connected to the negative pole of LED. When the LED should glow, it can be considered that the LED is working normally.
3. Set the multimeter to the position marked with the diode, and then use the meter pen to connect the two pins of the LED lamp beads respectively. When there is a digital display, the pin measured by the red meter pen is positive. If the lamp bead is red, usually this state will be lit.
4, pointer multimeter to 10K resistance file test, digital multimeter to diode file test, it is good to see that the light can be slightly lit. When measuring, the influence of the internal resistance of the multimeter should be taken into account.
5. Multimeter can only measure low-power ordinary LED lamp, if it is high-power LED lamp, high-voltage LED,COB integrated LED lamp can not be measured with multimeter. Some multimeters cannot be measured by ordinary LED lights.
6. the measuring current selects the measuring range according to the current in the circuit, from large to small, the black meter pen is inserted into the “COM” Jack, the red meter pen is inserted into the appropriate gear Jack, and finally connected to the circuit for measurement. However, it must be noted that when measuring current, the multimeter and the circuit under test should be in series.
How to use a multimeter to measure how much voltage led is lit
Power supply with 5V~6V voltage, a series of 100 ohms resistor, connected to both ends of the LED lamp, and then use the multimeter 20V voltage range to measure the voltage at both ends of the LED lamp, this voltage is the lighting voltage of the LED lamp.
Now the LED lamp bead, its voltage drop is generally about 3v, so the general multimeter can not measure it.
But that is not conventional), the second should be 5050 lamp beads, generally declared 0.2W, actually only 0.15W, the third is 5730 lamp beads, one is about 0.5W, the above are white light beads, so the voltage of each bead (that is, V F value) is 3-5V.
The power supply of the multimeter is 9V battery, but the output voltage is not that high at all. The LED can be measured with a diode gear, and the output voltage is a little more than two volts, which can make the lamp beads slightly bright.
When measuring the power supply voltage, modulate the multimeter to the voltage gear (distinguish DC from AC). Connect the positive pole of the black meter to the negative pole of the power supply in the red meter. The current measurement modulates the meter to the current gear (distinguishing AC and DC), the multimeter is connected in series to the input of the power supply, the red meter is connected to the positive pole of the power supply, and the black meter is connected to the positive pole of the LED power supply.
