

| Subject: | Re: basic electronics question |
| Date: | Fri, 26 Jul 1996 23:45:52 -0700 |
> Okay, now that there have been at least 6 different answers to what > resistor to use for the LED. Who has the final answer? This has been an > interesting string!! > > James The higher values are the safer ones, they pass less current, and generate less heat. I think all six answers were in the 200-300 ohm range, so there are not wildly differing views. I suspect all responders would not care if the 300 ohm value was the chosen one -- you just won't get as much light out. If you use the low end, you risk burning out your diode. Since a 1-watt (or even the 1/2 watt -- I think all were agreed on that) resistor is likely to be a 20% tolerance part, a 250 ohm resistor (meaning it's somewhere between 200 and 300 ohms) covers all of the responses. At 200 ohms, 60ma will be passed, which is *probably* ok, at 300 ohms only 40ma will be passed, which will not provide full brightness. Either of these extremes is probably acceptable. If they're not, you will have to find a more accurate resistor, or select one with an ohmmeter from a batch. Anything in this range is also probably ok -- it is certainly safe in the upper half of the range, so all of us pretty much gave the same answer... malcolm
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