Step 6: Test the LEDS

Connect you chosen power source and test that every thing is working. LEDs are directional so if it is not working try switching the leads.
just finished mine last night. doesnt look as good as yours (just used various paper i had laying around so it doesnt all match....and some of the shapes got cut off on the edge of the full page print, so i had to improvise), but i used 8 LEDs, so it's brighter.<br><br>used a 9v, a 9v cap and a little switch i had.<br><br>made it for the wife, so she can see her jewelry on her dresser. it's a dark side of the room where there are no outlets.<br><br>thanks again!<br>
i used this calculator which had me use 4 150 ohm resistors (9v, 3.2 fwd, 20 mA, 8 leds)<br>http://led.linear1.org/led.wiz<br><br>this one said to use 39 ohm<br>http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator<br><br>???
what is the purpose of the smaller piece?
The smaller piece is for extra support, so the lamp wont sag in the middle.
oh ok thanks. i thought so, but wasnt sure. just finished mine last night. doesnt look as good as yours (just used various paper i had laying around so it doesnt all match....and some of the shapes got cut off on the edge of the full page print, so i had to improvise), but i used 8 LEDs, so it's brighter.<br>
what is the purpose of the smaller piece?<br>why is it in all sideways?<br>you say to glue it in after the switch is in place, but there is no switch in this picture.<br>just a little confused on this step
The smaller piece is for extra support, so the lamp wont sag in the middle.
this is the best project and simple too.
how do you get usable light from a white LED through 33kohm at 3V? Or is this supposed to be some kind of microlumen night light?
Brilliant maby combine it with a joule-thief and a solar pannel then rename it the Green Lamp Also try sellin it as a kit
Brilliant! I love the idea, and your designs. You can bet I'll be making more than one of these.
Now that's a <em>really great</em> instructable! Well, at least it seems so... I have started building lamp1 as a reality test, I am already cutting for an hour, and now I cannot find any glue. Have to go shopping. Grmbl...<br/><br/>Anyway. There is also another option for power supply. With only one additional electronic element you can connect the lamp to the powerline! The following explanation is to also give the electrically innocent reader some insight. If you already know about it or if you think: &quot;I want a lamp and not a Ph.D.,&quot; then simply look at the schematic below.<br/><br/>Now for the math. We need some 20 mA for an LED. Each LED takes between 1.5 V and 4 V. You can look up the exact voltage in the datasheet - but for our lamp we only need to know that they consume at most a few volts.<br/><br/>Let's assume 3.3 V for a bright white LED. Two of them in series consume 6.6 V. From an AC power outlet we get some 115 V / 230 V (North America / rest of world). That's too much for our poor LED! It would simply explode in desperation from the current blowing through it if directly connected. We have to take care that it works as intended.<br/><br/>An LED conducts only in one direction. That's meant by 'directional' in step 6. We have AC. This means that an LED would only light up as the voltage is in matching polarity. But we connect half of them the other way round. This enlightens them alternatingly - at 60 or 50 times per second. Two fast to notice their short dark times.<br/><br/>Our LED limits voltage to 3.3V. We have four in total, connect half of them the other way round. Each group of two LEDs will be connected in series. Why not parallel? Well, no LED is like the other one. There are parasitic differences that might make one LED much brighter than the other one or even destroy it if we get the idea to use LEDs of different color or different brightness. In the instructable each LED has its own resistor which takes care of these differences as a side effect.<br/><br/>And to reduce voltage and current to an appropriate value we put a resistor in series:<br/>o (115 V - 6.6 V) / 20 mA = 5,420 Ohm <br/>o (230 V - 6,.6 V) / 20 mA = 11,700 Ohm<br/>Yes, I could have rounded to 5,500 / 12,000. Input values are not that exact. We only have to take care that no critical value will be reached.<br/><br/>However, if we simply take a resistor with the appropriate value, then our lamp would consume 2.3 W / 4.6 W. What a giant appetite for such a small, dim light!<br/><br/>Let's take a capacitor instead! A capacitor has an imaginary impedance called <em>reactance</em> depending on its size and the frequency: R' = 1 / (2*pi*f*C). f is at 60 Hz / 50 Hz.. R' - well, see above. Now solve the formula: C = 1/(2*pi*f*R'). This leads us to capacitor values of 470nF / 270 nF. Oh, here I've rounded. They are not produced on demand. They are not offered having arbitrary values. It's as if you want to by trousers. Go to the shop and ask them: &quot;Hi! I need four bright white LEDs and one capacitor of 489,406344071018867677994352314 nF / 272,05973178101766798099788610686 nF.&quot; They would probably answer: &quot;4 LEDs? Yes. But for the capacitor we can only offer 470 nF / 270 nF.&quot; <br/><br/>Ah, one final point! Each capacitor has a maximum voltage. Usually it is has even two values: one for AC, one for DC. The AC voltages you know are average values but in DC terms it has to withstand the peak values. At 163 V / 326 V they are much higher. Simply tell the shop you need them for a powerline application.<br/><br/>So. That's it. Quite some text. I'm exhausted. Be shopping now.<br/>--<br/>Airspace V - international hangar flying!<br/><a rel="nofollow" href="http://www.airspace-v.com/ggadgets">http://www.airspace-v.com/ggadgets</a> for tools &amp; toys<br/>
AAAaaahhh!!! I forgot one important point!<br/><br/>You have to insulate all wires used in this circuit in a way that nobody can touch them! Touching any electric wire in this device is <em>dangerous!</em> Touching this circuit can lead to death! You should even take care for cases the paperwork breaks while the lamp is plugged in.<br/><br/>Use shrinkwrap to cover all wires or insulating tape. This is important!<br/><br/>Maybe you should also add a resistor of 1 MOhn in parrallel to the whole circuit - i.e. from one plug contact to the other. The capacitor can hold a charge when you unplug the lamp. If you touch both contacts now you will feel that! Not dangerous, but tickling. If you bridge the plug with some metal after unplugging your lamp will flash.<br/>--<br/>Airspace V - international hangar flying!<br/><a rel="nofollow" href="http://www.airspace-v.com/ggadgets">http://www.airspace-v.com/ggadgets</a> for tools &amp; toys<br/>
<strong>Please forget my recent schematic!</strong> I blew a few LEDs with it. Not really sure how. Anyway, I found another circuit on the net: <a rel="nofollow" href="http://electronics4everyone.blogspot.com/2008/01/mains-led.html">http://electronics4everyone.blogspot.com/2008/01/mains-led.html</a><br/><br/>Watch the voltages! The author talks about 230 V. For American 115 V you have to double the caps. Recalculate to be sure.<br/><br/>Hmm... my circuit could work if we put a resistor in series... Have to think about it. Maybe I'll try.<br/>--<br/>Airspace V - international hangar flying!<br/><a rel="nofollow" href="http://www.airspace-v.com/ggadgets">http://www.airspace-v.com/ggadgets</a> for tools &amp; toys<br/>
Hooray for ASCII art!
you may be saved by the cap, but you will learn that LEDs although actually a diode, do not like to be used as a rectifier. over time they seem to get dimmer and dimmer. DC is by far better for them. pins 1 and 4 of a usb port give you 5.1 VDC. at 3.4vdc forward voltage for a white, blue, green or UV an 85 ohm resistor or the next higher fixed resistor should work very well. you can easily run 5 or 6 in parallel(each w its own resistor) without straining anything in the power supply; also, you don't have to throw away about 110 VAC as you do on 117 VAC mains power. with a slightly reduced current limiting resistor 3 1.5VDC cells can be used for a 4.5 VDC supply in the base of the lamp. one schmatic for a 117 VAC bulb uses a .5 mfd series resistor to limit current to 30 ma. next comes the bridge rectifierand a 200mfd filter cap. cross that w h high value bleeder resistor, and add a string of 33 identical LEDs and the appropriate current limiting resistor (270 ohms) and you have a 117 volt light bulb. it will consume about the same power as the rig above yet be about 20 times brighter. white LEDs in the 13,000 mcd to 15,000 mcd range are used for this. (why then do they cost $44 each???) please understand that i am in no way critterizing this author. the more people we have playing with these things the sooner we can be weaned from foreign oil. we are just now scratching the surface of that which is possible. keep up the good work. Less power to ya(in fact all of us.) Uncle Cy.
MAJOR MISTAKE: second paragraph .5 mfd CAP not resistor as i said above. sorry for not proofing better. this should be non polar and of 250 to 300 volt rating. twice what you will be using. 163 to 178 VAC peak to peak. 117 VAC average. i omitted the current limiter resistor above for the 4.5 battery circuit . it is 55 ohms(calculated). use the next higher fixed resistor. thanks fr listening. sorry fr being human and screwing up. Uncle Cy.
in which paper u printed
Nice .. I like. Perhaps it could be combined with the <a rel="nofollow" href="http://www.instructables.com/id/Make-a-Joule-Thief/">joule-thief</a>.<br/>
Good idea! You could run it on one of those huge 6V lantern batteries and it would last... um... I guess I don't really know how to figure for a joule thief... A LONG TIME!
True .. even with more LEDs I would dare to bet that the batteries would outlast the lamp.
100,000 hrs. = over 11 years. Somehow I doubt it would last <em>that</em> long...<br/>
Lol :D Perhaps not a practical solution after all.
And the LEDs won't get hot enough to light the paper on fire, not even close. Although the fire inspector would probably have no clue. "If it emits light, it gets HOT!!" he says.
I love this i can have my students do this as an electrical and paper craft!!! I really only have one thing to say <strong>BRILLIANT!!!!</strong><br/>
hah the brilliant thinggy reminded me of those guinnes beer commercials that used to be on the air not to long ago, my dad is the one that helps come up with that stuff lol
Very nice. You could double-stick-tape some tinfoil to the inside to make a reflector, or maybe use some of that "muffler tape" they sell at auto supply stores. It's basically just thick foil with adhesive on the back. Although I suppose with LEDs being relatively directional, maybe a reflector isn't needed...
Duuude! Paper craft + LEDs = win.<br/>This reminds me of the lamp I tried to make a few months ago. The parts are kind of just sitting on my desk waiting for me. And I'm... sitting here... on Instructables, not working on it. &gt;.&lt;<br/>
Gosh - I'll be passing this one on to our school's Technology department.
your school has a technology department?! I wish I was there.
Every UK middle and high school has a technology department...
ours has a furnace - nobody ever uses it though :(
ahh. the plight of the American schoolchild.
This is great. I'm making one this weekend! Just a thought, though...I was thinking if the LEDs were aimed upward and the interior of the shade was lined with foil the spread on the light would be softer and possibly brighter. I just don't know how much the interior part of the base takes up. So, I may experiment with that this weekend. Great project!
i've got paperkraft crazy as of late (surprisingly relaxing for it's complexity)....i may have to shell out the cash for pepakura
nice :)

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