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| Thread ID: 59525 | 2005-07-05 00:17:00 | LED Polarity? | SurferJoe46 (51) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 369506 | 2005-07-05 00:17:00 | Does anyone know what the polarity of an unmarked, yet one-leg-longer-than-the-other LED? :help: What I mean is that there is one leg longer than the other and that's the only mark I can find..is that the + ? I am used to seeing a little notch on the + leg.....but not this time..any ideas? |
SurferJoe46 (51) | ||
| 369507 | 2005-07-05 00:23:00 | en.wikipedia.org | bob_doe_nz (92) | ||
| 369508 | 2005-07-05 00:40:00 | Thank-you BOB.... | SurferJoe46 (51) | ||
| 369509 | 2005-07-05 02:04:00 | If you look at the side of the LED you can see the metal structure . The larger of the two pieces is the cathode (it's the "cup" which holds the active semiconductor element) . Some LEDs have the flat on the wrong side, some don't have a flat . I wouldn't be surprised if some have both leads the same length, or the wrong one longer . :( Anyway, as long as you have the correct resistor value, you can connect a LED either way with impunity . One way gives light . ;) The reverse voltage rating is usually about 5V, so I wouldn't try this with too high a test voltage . I often used to use the low ohms range of a multimeter (analogue . . . DVMs don't give enough current) to check the orientation . Incidentally, I have noticed that the high intensity LEDs have a yellow tinge (when not lit ;) ) . This is handy to know if you have a collection of clear LEDs and don't know which are HI and which are conventional . |
Graham L (2) | ||
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