LED light emitting diode distinguish between positive and negative? LED light emitting diode in the application process, often to identify the polarity of light emitting diodes. Light does not light is polarity, polarity welding upside down, lights are not on, following expanded small series teaches you to identify various types of light emitting diode polarity:
Straw LED anode
Relative to the SMD LED, straw hat LED lamp bead is negative relative easy to distinguish good, LED within two blocks of the PIN, we called the LED bracket, cathode supports relatively large, due to negative pole bracket support carrying LED chips, cathode supports smaller! So straw hat LED lamp beads bracket big connection of introduction feet is negative, bracket small links of introduction feet is cathode; General of straw hat LED lamp beads, we also can see he of introduction feet, general introduction feet short of is negative, introduction feet long of is cathode (certainly this method only in LED lamp beads compared new, introduction feet are sound of situation Xia, only can distinguish out) has many of method, to detection led plus or minus very, compared precise of method is with multimeter.
Multimeter test method. Upon detection of light emitting diode with a multimeter, you must use the "Rxl0k" file. Stuck as we've already talked about. Light emitting diode voltage drop is 2V. multimeter is in "Rxlk" and the following blocks. batteries only in the table 1.5V. Lower voltage drop. both forward and backward access LEDs cannot be conducted, it cannot detect ... Rx1k "table when the document inscribed has a 9V (or 15V) high-voltage battery, higher pressure drop, so it can be used to detect light-emitting diodes. Detection. two tables, one with light-emitting diodes connected to the two leaders, such as hands to deflect more than half, and has a bright point of light in LEDs, light emitting diodes are to access, and black tables (table connected to the battery positive) is positive and red table (connected with the battery in the table) is negative. Then after two table switch with light-emitting diodes, reverse access, hands should be fixed. If both access and the reverse access, hands are deflected to the head or do not move, then the led is damaged.