Instructables

Step 2: Grind The LEDs

Use the pliers to clamp the LEDs by the wires and grind down the lens part of the LED. Keep grinding it down until the side profile of the LED is square shaped - about as tall as it is wide.

The reasons for grinding the LEDs is both to make them lower profile, and also to frost the top surface so that the light output is diffused.

After grinding bend all the wires 90 degrees at the base of the LEDs. Bend all the wires the same way - polarity matters on LEDs. This will allow all the LEDs to be soldered together into one chain.

Step 3: Solder The LEDs Together

Simply solder the ends of the pins from one LED to the base of the next LED, and repeat until you have one straight chain using all the LEDs. Typically, 12 or 16 are enough for each shelf or cabinet. Make sure all the LEDs have the same polarity (longer pin on one side, shorter on the other.)

After soldering, check if the chain is straight - resolder the crooked links until the LEDs form a straight line.

Test the string with some button cell batteries or with the 3 AA/AAA battery pack.

Step 4: Add The Switch And Power Supply

Find a convenient place where you will be placing the power supply, power switch and the LEDs themselves within your cabinet and measure the amount of wire you will be needing.

Solder the wires to the LEDs. Solder the negative wire straight to the battery pack or power supply and solder the positive wires to the power switch.
 
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mu0p7 years ago
Excuse my poor knowledge in electronics, im just starting out.. but, to my understandment now, each LED is about 3.5volts and you used 16 LEDS which would be about 56 volts and for you power supply you used 3 1.5volt AAA batteries which is exactly 4.5 Volts in power. which is no where near 56.. So my question how did you power 16 leds with just 4.5volts of power? ive been wanting to wire my leds in a line like this forever, but just couldnt figure out the volts/power thing if anyone can help that would be great!! thnx in advance!
sockmaster (author)  mu0p7 years ago
If all the LEDs are wired in series (the positive pin of LED1 is wired to the negative pin of LED2, the positive pin of LED2 wired to negative of LED3, etc....) then, yes, it would require 56 or so volts. If all the LEDs are wired in parallel (all the negative pins wired together, and all the positive pins together) it requires 3.6 volts - same as using just one LED.
just want to add to this that in series connection there is a voltage drop on each component while in parallel connection there is a current drop that the longer you put a component the current supplied to it will be lessen.
Im new to this too, hence the mind blown picture i use. Im learning new things every day on this website and you my friend have just taught me something else :) thank you
In this project are the LEDs connected in series or parallel?
sockmaster (author)  uuili7 years ago
These are connected in parallel
how long does it last on those batteries?
mu0p sockmaster7 years ago
thnx for the reply!! but one last thing, if say using 4.5 volts to power 16 leds in a parrellel... do they all recieve equal amount of good power, or are they dimmer then they should be since sharing so little power
Bob7k mu0p7 years ago
dimmer, but it works. i think this is a good idea, i wonder whare i can put something like this... did you think of using surface mount LEDs?
Eugene20096 years ago
LED's are non-linear devices. As you apply more voltage the current increases more than 1 to 1. LED's are specified at a particular forward voltage and current. a typical white or blue LED may be spec'd at 3.3V @ 20mA. If you apply a regulated 3.3V across a white LED the draw will be 20mA typical. You can get by not using a resitor to limit current. If you put 2 matched LED's in parallel the total draw will be 40mA. This equals a power of 0.132W. If you put these LED's in series and apply 6.6V the total draw is 20mA. This still equals 0.132W (TANSTAAFL). If you apply 5V to a typical 3.3V LED the current will go up to hundreds of mA and exceed the max power rating very quickly and burn out (remember non-linear). In this case you want put a resistor in series. The correct value would be the voltage drop (5V-3.3V=1.7V) divided by the current (0.02A or 20mA) which is 85 ohms. Different LED colors have different voltage ratings at 20mA. Red is 1.8V, green, amber and yellow is 2.1 to 2.5V and white and blue are 3.3V. If you test a batch of LED's with a constant current source (20mA) you would find some variation in voltage (3.0 to 3.5V)so if you apply a constant voltage (3.3V) across this same batch you will see some variation in brightness because brightness depends on current. To run LED's off of AC source you must rectify the AC(117Vrms*1.414=165.4Vpeak)and series wire 50 white LED's (165.4/3.3). If you use fewer LED's you have to calculate the proper resitor (don't forget to use the right power rating P=V*I). Rectified AC may cause a flicker that some people will notice. Using full wave rectification and a high voltage (300V) filter capacitor will help minimize this.
This is the best explanation of LED behavior I have come across in a long time. Keep up the good work.
ouss763 years ago
Hi
as i know, it isn't nice to drive a led without a resistor...
Mmmmm Goldschlager... Anyway, wouldn't it be nice to add a diffusing panel across the strip, so the lighting isn't so localized?
wiloland8 years ago
Hello, How long does the battery last?
baki22 wiloland7 years ago
hai every one , can used cell phone battery for the power this Led it 3.6v thanks,but need charging port for charge again Thanks
Hey, thats a great idea! Just mount it and drill a hole to where you can just pop in a charger. Thanks!
quanta6 years ago
You can't just connect the LEDs to the power source directly. You have to use the combination "LED+resistor" in order to manage the current. Well, if you have a power source giving exactly 30 mA (which these types of LEDs need), then that's OK. In this connection, both the LEDs (life of an LED is 100000 hours) and the batteries will die soon. Now, the LEDs need the current somewhere around (16*30) = 480 mA. As i see in these pictures, the batteries are just plain types. To conclude, the won't last long. (excuse me about my grammer, if i make mistakes; english isn't my native lang)
Darkshot quanta6 years ago
hmm i see your point, but wouldnt the LED's give out less light?
montiet7 years ago
correct me if I am wrong, but if I used 10mm leds with a volatage rating of 3-3.6 and used a 3 AA battery pack which uses a series configuration it would put out 4.5 volts which would fry the led?
interesting. How then would I go about installing a strip of these powered by a 12v battery? I'm looking to install something similar in my boat.
A good way to do this is by wiring 3 LEDs in series with a resisitor to create a cell, then connect addition cells in parallel. Calculations for resistor need to be made depending on the specification of the LED. Typically it is not recommended to wire LEDs in series, if one LED shorts or goes open, then all the LEDs in that cell go out. Personally, in practise, I have never seen it, but it is still possible.
schimmi TLLCUK6 years ago
what if you don't know the voltage of your LED;s because you raped them from some christmas light string?
I live compeltely offgrid and am constantly looking for ways to conserve electricity. I'd love to know exactly how you end up converting this to 12 V
TLLCUK GEris7 years ago
We have a 30cm led strip which use either surface mount or 5mm leds. Both types operate from 12vdc and come in all standard colours. Alternativley they can be made DIY, all you will only need is, LED, resistor, stripboard (veroboard), connectors and wire. Calculations can be made to select correct type of resistor depending on the LED spec and the input voltage (in case you want to run it from 6v, 24v etc. Circuit can be modified to run from the mains or even to drive high power LEDs such as Cree or LumiLEDs. In fact, the circuit can be further extended to run RGB, either single colours of 3 in 1 packages.
I use a little web calculator to figure out what value of resistor to use for LEDs. It works for just one LED or for a number of them wired in series.

LED resistor calculator

As a side note, it is indeed wise to use a series-parallel circuit rather than wire a whole bunch of LEDs in series. It would work fine for a while, but the lifespan of the LEDs would probably be reduced. Make series-wired clusters of just a few LEDs, each cluster with its own appropriate resistor, and then wire those clusters to your power source in a parallel circuit.
sockmaster (author)  tinkertodd7 years ago
You might either try using resistors to drop the voltage to 3.5 volts (not sure what value you'd need to use), or wire multiple sets of LEDs in series to divide the voltage (eg: 12 volts divided into 4 sets of LEDs means each set gets 3 volts.)
Thanks! I'll give it a try. Happy Hoildays!
sockmaster (author)  montiet7 years ago
4.5 volts is a little high and some LEDs might not like that, but it seemed fine when I first installed it. I switched to rechargeable batteries, which are 1.2V after I took the pictures and 3x1.2V = 3.6V, perfect for 3.6V LEDs.
sockmaster (author)  montiet7 years ago
Possibly. It would depend on the voltage drop caused by the resistance in the painted conductive traces. But if you plan on using 3 AA batteries, you might try using rechargeables which are 1.2 volts instead of 1.5 volts, which would make the power source a safer 3.6 volts.
sockmaster (author)  sockmaster7 years ago
Sorry! I was thinking of my other instructable when I answered the above! Ignore that part about the conductive paint :) ...but 1.2 volt rechargeable batteries are still preferred because it'll keep the output within your LED's 3 to 3.6 volt range.
uuili7 years ago
Im brand spanking new to electronics so i have a few questions here. If you use say 20 LEDs in series, can you still power them with regular batteries as in this instructable? I would like to use the mains to power the LEDs. What changes will I have to make to the configuration and will I need extra components? Really want to make one of these!!
downgrade uuili7 years ago
if you follow this instructables, more LEDs just takes more amps which means it eats through power faster, doesn't need more... to use it from the mains is a bit much considering LEDs like DC, and instead of 120v they prefer something between 2 and 3 volts. so what you might want to do is find a properly powered wall charger for some lost electronic device and use its wiring. So if you can find a wall charger that puts out very close to what the LEDs you have wants to use, there you go, quick solve to a big question
uuili7 years ago
I am totally new to electronics, here goes: You can use 20 LEDs in series and power it with 2 or 3 1.5V batteries? Also how would you go about using the mains to power these LEDs? Safely of course :)
thegreatguu7 years ago
I just did somethin llike that ...really great: cold light, just enough to see the keayboard without light blinding you :D Would anyone have a link or something to explain how to power this with usb?
wargo08137 years ago
super sweet idea
Neat idea. Would be really cool if you just added a small lip on the front/top of the shelf, and hid the LEDs behind that. This would make for a great little keyboard light for those of us with slide out keyboard drawers.
where is a good place to get bluk LEDs for a good price
There are several LED companies from Hong Kong doing business on Ebay. You can get some great deals on packages of 100 LED's for about $20, and they include resistors. You may not need the resistors, because you should run the LED's in series to avoid wasting power. You should only use a resistor to fill in that last few volts. I plan to do an Instructable on LED voltage and current calculations.
montiet7 years ago
Anyone know how to run power from a wall socket to this? what would you need to do this?
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