It varies depending on the LED. In an electronics catalog I got last year, I see forward voltages ranging from 1.5V to 4.8V (that high one was blue). I'd expect it to be constant for a particular LED.
Maybe if that voltage is EXACTLY right. Theoretically, you might see this a few times during the life of the universe. In reality, don't expect it.
Yes. I have one of those 3W LED flashlights. It's brighter and whiter than an incandescent flashlight.
Not necessarily. As I said in another message, some LEDs have forward voltages that high. That's the LEDs themselves.
I do. That's something that would have helped make it look like I was saying to use 12V.
I put in the word "OR" at the beginning of the line in question. Did you forget what "or" means? This was something that would work INSTEAD of "series and 12V". Why assume I meant something other than what I said?
You *were* saying to use 12V. Look at the sentences. OP said daughter thought you needed to use a 12V supply for two 6V lamps. I said not a problem if you connect them in series. You said "or in parallel."
And that's not correct. Do that, and you'll burn them out.
The discussion to that point had concerned itself only with 12V supplies; thus, in the absence of any qualifying clauses specifying a different voltage, subsequent statements must be taken as referring to the 12V supply under discussion. If you *meant* "or in parallel, using a 6V supply" then you should have *said* "... using a 6V supply."
I know perfectly well what "or" means -- it means you were suggesting an alternative. The flow of context makes it very plain that the meaning of your suggested alternative was to connect them in parallel to a 12V supply, as opposed to my suggestion to connect them in series.
I *am* assuming you meant *exactly* what you said. The problem is that you apparently didn't say what you meant -- if you *meant* 6V, then you needed to
*say* 6V.
If you're going to be pedantic about it, "a resistor" isn't equivilent to "resistance", or to "limited current", either.
Considering the circumstances, I doubt that that is the case here.
Bob
What I said definitely IS the case. What I said is just to disagree that "3V" IIMPLIES "internal resistor". Nothing else.
These are "3V LEDs" provided for a school project. These would seem very likely to be LEDs designed to operate easily off of
3 volts, since LEDs are rarely described as "X volt" in any other circumstance. Certainly not at the "consumer" level.
Mark,
If I may interject here ... The discussion was about connecting 6V lamps to a 12V supply. As you said, you didn't mention anything about changing the supply to 6V. It's perfectly reasonable for Doug to assume you were still talking about a 12V supply. End of story.
Respectful regards,
Mark
The discussion was about 6V lamps, "12V" was a later addition, which I posted an ALTERNATIVE to. Sorry for not making things clearer.
I didn't say 6V because it was ALREADY 6V, as appropriate for a 6V lamp (perhaps I underestimated people's lack of knowledge). As I did mention, it would have been better to have included that information anyway. I apologize for the mistake I did make, just not for the one I didn't.
No, it was not -- the 12V is in the ORIGINAL POST.
Wrong again. The ORIGINAL POST was complaining that the subject had been explained so poorly in school that the OP's daughter thought she needed a 12V supply to power two 6V lamps.
I said that was fine, if they were wired in series.
You said "or in parallel, if the power supply is big enough."
The only lack of knowledge apparent here is yours. It's not quite clear whether that lack is in the difference between series and parallel wiring, or in reading comprehension.
You still haven't figured out which mistake you really did make, and I'm still waiting for your apology for accusing me of having put things into your post.
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