What is Digg?37 Comments
- BrettE, on 10/12/2007, -0/+12Just remember:
0 Bad - Black
1 Beer - Brown
2 Rots - Red
3 Our - Orange
4 Young - Yellow
5 Guts - Green
6 But - Blue
7 Vodka - Violet
8 Goes - Gray
9 Well - White
Once you have the three numbers (say xyz) the resistor is xy followed by z-zeros Ohms. - t3hX, on 10/12/2007, -0/+7Umm, wash your hands after soldering. That's really all it takes.
Or just buy lead-free solder. - BrettE, on 10/12/2007, -0/+7I keep seeing advice on the web that advocates using LEDs without resistors if you match the voltage of the supply to the voltage rating of the LED. This seems like a bad idea. An LED is a nonlinear device, in other words, as you increase the voltage, the current does not increase linearly.
With an ideal diode, once a certain voltage is reached, current goes to infinity. It's like this you see: think of an LED as a sticky check valve in a water pipe system. You must build up enough pressure to open the valve, but once it's open, it lets water flow through freely! With an LED, you must apply enough voltage (bias) to get the device to allow current to flow. If there's nothing there to limit the current (like a resistor), you will likely overheat the device or drain your batteries quickly.
Obviously a real battery can't supply infinite current, and a real LED has parasitic resistance, but still, it's just good practice to put a current limiting resistor in there.
Brett - Settra, on 10/12/2007, -3/+9It would have been better written by someone who knew something about basic electronic, such as resistor labeling.
Still a great article, though. Dugg. - Poppeseed, on 10/12/2007, -0/+5Even if you do use the solder with lead, don't worry unless you live in California, as that is the only place it will affect you.
- inactive, on 10/12/2007, -0/+4Dugg, if only for the link to this:
http://www.dannyg.com/examples/res2/resistor.htm - mohaine, on 10/12/2007, -0/+3Of course color coding is useless for people who are color blind/insensitive.
The easiest way is a digital multimeter with an ohm tester. - luma, on 10/12/2007, -0/+3Who dug this down? He's entirely correct - placing an LED into a circuit w/o current limiting is a great way to toast said LED (and potentially the power supply) in very short order. This entire instructable is wrong on so many levels it's hard to know where to start.
- netdroid9, on 10/12/2007, -0/+3Phh, does it really matter? People drink beer, smoke, and do all kinds of stupid things involving chemicals. Chances are, your PC uses ***** of lead solder anyway. So long as you aren't actually eating the solder (Or resealing cans with it), you should be fine.
- Haplo, on 10/12/2007, -0/+2Bit harder, but way cooler: http://johnbokma.com/pet/scorpion/detection-using-uv-leds.html
Scorpions (and some other animals) "glow in the dark", and hence UV LEDs are an easy way to locate them because scorpions are mostly active at night. Video which shows "glowing" scorpions: http://hackedgadgets.com/video/mexican-scorpions-uv-john-bokma.wmv - nicktripp, on 10/12/2007, -0/+2I disagree that this article would have been better written by "someone who knew something about basic electronic". This is exactly the kind of article that can give someone their first experience with electronics. That being the case, basics like how to read resistor labels are great information to have in there. The author was learning as he went, which is what a lot of people do when they're just starting out. That kind of writing makes it an easy read for beginners, which is who the article was targeted at.
- kinapuffen, on 10/12/2007, -0/+2Great for all people that want to start with electronics. Just one thing that the author got wrong:
Do NOT put a LED or a series of LEDs without a resistor. A LED is not as the author claims driven by voltage it's driven by current. A LED or any diode have a voltage rating. For example lets say it's 1.5V. If you have a source with 1.2V the LED will not let any current through, but if you have a source of 1.5 or 1.6V the LED will let an enormous amount of current through. This will shorten the lifespan of the LED dramatically. It basically works like an on/off switch. - Genghis1, on 10/12/2007, -0/+2Bad
Boys
Rape
Our
Young
Girls
But
Violet
Gives
Willingly - brewpoo, on 10/12/2007, -0/+2Why didn't he use a breadboard for the demo? Seems silly.
Anyway, ALWAYS use a resistor with an LED. And when wiring LEDs in parallel, you should use a resistor for each LED involved. This is especially important for mixing LEDs as the LED with the lower bias voltage will conduct first. Even in similar LEDs, doping results in slightly different bias voltages. - Anomaly427, on 10/12/2007, -1/+2Uh... I think articles like this should be used as a retard filter for Digg. You digg this, you lose your account.
As the first poster said - it should be (and probably has been) written by someone who has the first clue about electronics. - ricksite, on 10/12/2007, -0/+1Soldering directly onto a battery may not be the best idea. The heat can damage the battery amongst other things. Batteries can be spot welded or you can just use a battery holder.
- sishgupta, on 10/12/2007, -2/+3Jeez he spent half the instructable explaining parallel vs series. I think they taught us that stuff in a public grade 5 elementary school. He wasn't kidding at all when he said that instructable would be overly simplistic.
- sblancha, on 10/12/2007, -0/+1Essentially he was documenting his learning process. Which is valuable to others whom are just starting to learn about these things. "Son, don't make the mistakes I did. Drinking, womanizing, and wiring LEDs in a circuit without a current limiting resistor, these are all a sure path to Hades." I didn't find it condenscending at all, actually some electronic books can quickly become daunting for that reason.
Because he knows nothing to begin with, the language is geared to those that know nothing. Sometimes even basic electronic books are bogged down with these crazy concepts of voltage and current, resistance, parrellel and series. Things that anyone with some exeperience has ingrained in them as instinct and can't possibly fathom someone not understanding how series and parralel are different and why, "IT'S OBVIOUS, JUST LOOK AT IT THERE, CAN"T YOU SEE THE DIFFERENCE!" me yelling at my son whom didn't understand, after the tenth time showing him. He would probably be able to follow this one. - legendxx, on 10/12/2007, -1/+2or just buy the ones at radioshack that have the resister built in and are 10 times easier to mount to anything
http://www.radioshack.com/search/index.jsp?kw=led&f=Taxonomy%2FRSK%2F2032297&cp=2032058.2032233&kwCatId=2032058&categoryId=2032297&fbc=1&f=PAD%2FProduct+Type%2F%3E7+mm+lens&fbn=Type%2F%3E7+mm+lens
And that concludes my tutorial for 'complete retards' - amboy00, on 10/12/2007, -0/+1Dude, I'll digg you just for making the cool beer reference. Using liquor in mnemonic devices just makes learning better!
- Haplo, on 10/12/2007, -0/+1"Umm, wash your hands after soldering. That's really all it takes."
No, that's not. If you solder, especially at a bit higher temperatures to go faster, it might be a good idea to have a small fan blowing away the fumes. - BigSlacker, on 10/12/2007, -0/+0If you want to mess around, just get a breadboard and a meter. Even better spend the $60 or so for the radio shack breadboard kit that comes with a ton of components including a bunch of standard ICs. The instruction book takes you step by step through analog and digital circuitry. If you really want to get serious and understand what's going on, you'll need to pick up an oscilloscope too.
- crash128, on 10/12/2007, -0/+0Online education has a good future - how-to's, hands-on learning with pix (I thought the photos were pretty good) & video, mp3's, pdf files for courses. He should offer kits for sale with all the parts (rshack cut way back on parts in my area). Throw in some email/im tech support (and message boards, peer help). Let the students create a wiki. Damn, that sounds pretty good (yea, I know, I've seen the ads for the online universities, just never tried one).
Someone should do the same (webify) Forrest Mums book "Getting Started in Electronics".
Open Education Now! (shoot, already got a slogan). Break the Marxist death grip of the mediocre NEA on America's future! (ok, overreaching a bit). - BigSlacker, on 10/12/2007, -0/+0Probably the internal resistance of the battery is what saved the LED from frying, but I agree. A shorted circuit is a bad circuit.
- anatols, on 10/12/2007, -1/+1this way I burnt out tons of leds, transistors and other stuff before I found my first book on electronics. in any case this was dumb, but it was real fun
- EntangledPhysx, on 10/12/2007, -1/+1I just use the back of a RadioShack resistor package
- BrettE, on 10/12/2007, -0/+0@Haplo
The fumes contain no lead. Lead boils at an insanely high temperature: 3164.0 °F. That's much hotter than a soldering iron. The wisps you see are NOT lead. Washing your hands is, in fact, the most important method of preventing lead ingestion after soldering.
Brett - bullrassler, on 10/12/2007, -0/+0Yeah, battery internal resistance it is. I looked at the LED board in a flashlight. Something like 21 white LEDs. powered by 3 AA batteries, (nominal 4.5 volts), the LEDs were white (nominal voltage 3.5?). All 21 diodes were in parallel, no dropping resistor or equalizing resistor anywhere. Sigh.
Still, the thing worked fine, and probably cost-effective and all, it just doesn't seem _right_. Probably still 10x the battery life of an equivalent bulb-type flashlight. - MorningCoder, on 10/12/2007, -1/+1Buying parts from RadioShack implies the author haven't spent much time with electronics or he is rich. I haven't been to RadioShack in ages. How much does one of those individually packaged LED cost nowadays? It used to cost at least 5x as much as other real electronic parts stores where you can buy them unpackaged.
- JimTheCactus, on 10/12/2007, -0/+0Okay, getting the details straight:
LEDs are typically modeled by a single voltage drop. In this ideal model, if you hook it up directly to the battery, you move infinite current and ultimately the LED must dissipate infinite power (meaning it burns up.) This isn't exactly true, but is close enough for experimental purposes. Don't hook one up this way unless your willing to fight with the more advanced models that more accurately model diode current.
However, working with diodes is easy. Using the ideal model, one can simply take their source voltage and the diode's recommended drive current (which if it isn't marked is probably 20mA,) and solve for the resistor needed to get that current. For those of you who don't feel like becoming electrical engineers just to make a stupid light turn on, this resistor would be:
((Supply Voltage)-(Diode Voltage))/(Drive Current)
Getting this exactly right really isn't important. Get it close and you'll do fine. The only time this really matters is when the precise brightness has to be controlled.
Also remember that brightness is controlled by drive current. More drive current, more brightness. The rating of brightness (usually listed in mcd, or microcandellas) is the brightness you'll probably get at the current listed on the package. However, if you exceed the maximum rated current your diode isn't long for this world and will burn up. (I actually had one blow fast enough that it cracked it's plastic case.)
If you want to run multiple LEDs, first make sure that the sum of all the diode voltages is bigger than your power supply voltage. (a 9v battery can run 6 1.3v LEDs.) Then simply add up the voltages and use that number for "Diode Voltage" in the formula above. For example 2 3.5 volt white LEDs has an effective diode voltage of 7 volts (3.5 volts + 3.5 volts.) If we have a 9 volt battery, then our resistor is (9V-7V)/(.02A) = 2V/.02A = 100 Ohms. This, using the table in the higher post, would be a brown black brown resistor. (The fourth band can be just about anything for this purpose since it only tells us how close to 100 ohms it really is.) - HarryManback, on 10/12/2007, -1/+0I can't wait until I'm completely bored and out of every available light source to give this a try.
- StrokerAce, on 10/12/2007, -1/+0Or, you could just go hog f'in' wild at http://www.gelcore.com - they've got about all the LEDs you could think of, only they're a bit on the pricy side. I used to work in industrial signage, and neon channel letters are slowly becoming a thing of the past. Red LED is already comparable to red neon pricewise. I shan't ramble on about channel letters, though - most people (no Digger's, of course) thing they just make magical bendy flourescent tubes for any shape, font or size of letter. God that got old....
- ithildin, on 10/12/2007, -3/+1Nice idea but it was made too simple to the point of being condescending. I learned this and much more at electronics classes in high school.
- stuffhappens, on 10/12/2007, -8/+3Nicely laid out, if simplistic, article. UK-based readers could always dive in to a 'local' Maplin store for supplies or order online from places like Rapid: http://www.rapidonline.com/home.aspx (or Maplin: http://www.maplin.co.uk/)
If you want to get 'into' electronics there's tons of articles on the Internet - and the low-cost books from these guys have been around for some 60 years: http://www.babanibooks.com/bb7.htm
Not Dugg though due to serious apostrophe abuse. - inactive, on 10/12/2007, -8/+1is this a "for beginners" or for "complete retards"
because yeah, hooking up a battery to an LED makes it light up? damn, never knew that, but wait.. the led gets hot! and is far too bright! maybe we need to .. to.. resist some of the batteries power! but what on earth RESISTS electricity? oh! i know! resistors! i'll throw in random resistors until i find one that works.
wow, trial and error sure is a difficult way to learn, eh? - TheFunnyDigger, on 10/12/2007, -10/+2Yeah. digg me more.
- huiezer, on 10/12/2007, -11/+1i dont want to mess with that lead stuff cuz you can get poisoned
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