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WTF resistors Answered

I just got a back of about 130 resistors for a bag of 50 L.E.D's but some of the resistors ive never heard of, there are a few like 100ohm and 560 ohm but now im getting 1m ohm and 4.1Mohm and 100K ohm,1.5K ohm and 1K ohm. Ive never seen resistors like this before, i am very basic in electronics but i took a class at school have have made many many projects but never resistors like this and i only wanted to use them for a few L.E.D's, I dont really know what im asking for in here but i just sapose if anyone has any help or ideas or really anything with these resistors and matching them with L.E.D'S?


the resistors that you got are for multiple purposes, there are millions upon millions of different values of resistors, each limits a different amount of power

Resistors resist the flow of electrical current. If you would connect an LED to a 9 volt battery, it would die very quickly. However, if you put the correct resistor in there was well, it would allow the LED to burn for many hundreds or even thousands of hours.

I hope that makes sense. It's very basic.

Here is more on resistors if you want to read it:

I don't understand exactly why we need resistors for LEDs. I can use LEDs fine without resistors and I can't see anything happening to them.

their life will be drastically reduced. Here's an analogy for you: you are shooting a machine gun at somebody "what? they're still alive.... (for now!!!!)" you are shooting someone with a nerf gun, they're going to stay alive for a lot lot lot longer until they die of old age (about 100,000 hours for an LED) bad analogy? I know

That makes sense, even though the analogy doesn't. Shouldn't the analogy be like if you shoot someone, they die quicker than if you shoot them while they are wearing kevlar. In that case, the kevlar would be the resistor. Does the resistor lower the current? Because I would understand if the un-reduced current burns out the LED quicker.

Where did you get your resistors?

in an Australian store called disk smith

hmm does anyone know a link to a more thorough calculator? i have several resistors with 2 gold bands, and more then 4 bands also some with no bands

the ones with 2 gold bands range from 1ohm to 9.9 ohms

k, cool. what about ones that have like 5 bands? and what about the ones that have the gol dband between colored bands?

One percent resistors will have 5 bands, I think. Three significant digits, a multiplier, and a tolerance (Brown for 1% according to wikipedia) Gold in a spot other than tolerance is a 0.1 multiplier,
so red red red gold brown should be 22.2 ohm, 1%. Red red gold gold would be 2.2 ohm, 5%.

so is the problem you dont know what resistor to use? google led calculator.


10 years ago

Standard 5% resistor values range from about 1 ohm to about 10M ohms; there's a standard set of values, about 10% apart. (There are even more values of 1% resistors!) Yeah, for most digital apps, most of them are generally not useful AS THERE EXACT VALUES, but for most of those circuits there's quite a lot of range where you can substitute. I figure values less than about 4k are good for current limiting, 4k-100k is good for pull-ups, and 100k-10M show up in human-oriented timing circuits (1Mohm*1uF is a 1s time constant.)

wow thanks, so pretty much anything less than 4K would be good to use in an L.E.D for a Wii remote that uses two AA batteries?

For an LED you'll usually want something under 1k. The higher values would come into play for limiting current through a transistor switch, for example. (For 2 AA batteries and typical LEDs, you're probably looking for something closer to 100 ohms or less.)

Well if you get tired of them or something, you can sell them. Maybe use them for other LED projects, then you don't have to go and buy them over again and again.

no no, its not that i have to many, i just dont know what resistors to use. I have 1ohm, 4.1Mohn and everything in between