How does the multimeter measure the LED light?

With the development of electronic technology, daily lighting has kept up with the trend, and added electronic technology. In order to save energy, LEDs (light-emitting diodes) are also used for lamps, and dozens of high-energy LEDs are connected in series and parallel.

There are many ways to supply LED tubes. Usually, there are switching power supplies and RC series power supply. The switching power supply has high efficiency, the market voltage fluctuation has little effect, but the cost is high. The RC series is more common and energy saving. .

It is impossible to judge the quality of the lamp by a single universal meter (except for complete breakdown).

The polarity symbol of the diode is A for the anode (commonly known as positive), K for the cathode (commonly known as negative), and the current is generally flowing from A to K. The brightness of the LED lamp is measured by lumens, and the illumination distance is related to the wavelength.

Measuring a single LED with a universal meter depends on whether you are using a mechanical needle type universal meter or a digital universal meter. The polarity of the two models is different. The black pen of the mechanical watch (negative meter pen) is connected to the positive battery of the battery. The red pen is connected to the negative pole of the circuit inside the meter. When measuring, the position of the file is RX10, the black pen is connected to the long leg of the LED lamp, the red pen is connected to the short leg of the LED, and the light is bright, but some special lamps need to be powered. The built-in battery of the mechanical watch usually has only 2 knots (3V), and it is impossible to measure its quality. The digital universal meter measures the LED, because the red test pen is connected to the positive pole of the universal meter circuit, the black test lead is connected to the negative pole of the battery, the measuring position is Rx20, the red pen is set to the long leg of the LED, the black pen is set to the short leg of the LED, and the light is bright.

With the popularity of LEDs, more and more people are aware of the energy-saving and pollution-free characteristics of LEDs. They have chosen LED lamps as the preferred lamps. In addition, LEDs are also widely used in home appliances, some indicators, and operational indications. and many more. When we need to repair these LEDs, we often need to identify the quality of a chip. Let me introduce you below.

Electronic multimeter

LED lamp beads, various types, straw hats, patches

Observe the appearance of the lamp beads

Differentiate the anode and cathode of the lamp bead

The multimeter gear is adjusted to the "transistor file"

The multimeter red pen is in contact with the lamp anode contact body, and the multimeter black pen is in contact with the cathode contact body. Observe if it lights up.

If the light is on, it means that the function of the lamp bead is basically unaffected. If it is not lit, exchange the red and black test leads and test again. In order to avoid the anode and cathode of some lamp beads, the opposite is true.

The lamp bead is lit to observe the color of the lamp bead, and the color temperature meets the requirements. Is the brightness appropriate? Choose the right lamp bead.

END

Precautions

Generally, the LED lamp bead has a forward voltage drop of 2..7-3.6V. Please do not add a voltage higher than this value to both ends of the lamp bead.