The LED lamp bead is actually a light-emitting diode, which will emit light when a certain voltage and current are loaded. Generally speaking, the voltage of a single LED chip is about 3V, and the current is 30mA, and the voltage and current of the LED lamp bead are mostly determined by the series-parallel relationship of the LED chips during the LED packaging process.

The most used 0.2W LED lamp bead in the lamp tube is composed of two LED chips in parallel, that is, 3V, 60MA. As for the high-voltage LED 9V lamp beads that are most used in the resistance-capacitor power supply, it is composed of three LED chips connected in series, that is, 9V, 30MA.

Because LED lamp beads are made of multiple LED chips in series and parallel, there are many specifications and voltages of LED lamp beads. The specific number of lamp beads can also be seen by how many LED chips the lamp beads are composed of. Of course, because the LED chips are relatively small and the gold wires for wire bonding are relatively small, visual inspection can only be roughly estimated. You have to test it with a DC source.

However, 3V, 6V, 9V, etc. are used more. Of course, there are also tens of V lamp beads. This depends on the specific design scheme to really use what kind of lamp beads.

For the lamp bead with only 3V, you can use the diode gear of the multimeter to light the lamp bead. This is positive and negative. If it is not bright, just change the positive and negative. For LED lamp beads that do not know the voltage, it can only be measured with a DC source. The method is: adjust the voltage of the DC source to zero, adjust the current to the maximum, connect the positive and negative poles of the lamp beads, and adjust the voltage of the current source to make it It increases from zero, and when the lamp bead is slightly bright, the voltage at this time is the approximate voltage of the LED lamp bead.

For COB lamp beads, it is actually a principle, but COB encapsulates more LED chips, and the voltage and current will be relatively large. The method of confirming the voltage and current of the COB lamp bead is also confirmed by the DC source.

Using a DC source to confirm this is the simplest and most rude method, and it is the most widely used in the development process.

Each specification of lamp beads has its own characteristics, some are more cost-effective, and some have better performance. And the LED lamp beads of the same specification will be different between each manufacturer, so the LED lamp beads are not absolutely good or bad, as long as they are used well, they will play their greatest role.