This instructable shows how to wire up one or more LEDs in a in a basic and clear way. Never done any work before with LEDs and don't know how to use them? Its ok, neither have I.
***If you have wired up LEDs before, this explanation might seem overly simplistic. Consider yourself warned.***
***If you have wired up LEDs before, this explanation might seem overly simplistic. Consider yourself warned.***
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Signing UpStep 1: Get some LEDs
So I wasn't completely honest - I have used LEDs once or twice before for simple applications, but I never really knew what I was doing, and since so many projects on instructables use LEDs, I thought I might as well teach myself and post about it too.
I know that there are many projects already posted that contain information about how to wire LEDs for simple projects - LED Throwies, LED Beginner Project: Part 2 and 9v LED flashlight - teh best evarrr!, but I think that there could still be some use for a detailed step by step explanation about the basics of LEDs for anyone who could use it.
The first step was to buy some supplies and figure out what I would need to experiment with. For this project I ended up going to Radioshack because its close and a lot of people have access to it - but be warned their prices are really high for this kind of stuff and there are all kinds of low cost places to buy LEDs online.
To light up an LED you need at the very minimum the LED itself and a power supply. From what I have read from other LED instructables wiring in a resistor is almost always a good idea.
If you want to learn about what these materials are check out these wikipedia entries:
LEDs
Power supply
Resistors
Materials:
LEDs - I basically just reached into the drawer at Radioshack and pulled out anything that wasn't more than $1 or $2 per LED. I got:
2760307 5mm Red LED 1.7 V
2760351 5MM Yellow LED 2.1 V
2760036 Flasher Red LED 5 V
2760041 2 Pack Red LED 2.6 V
2760086 Jumbo Red LED 2.4V
Power Supply - I really didn't know what I would need to power them so I bought some 9V batteries and some 1.5V AA's. I figured that would allow me to mix and match and make enough different voltage combinations to make something light up - or at least burn those little suckers out in a puff of smelly plastic smoke.
Resistors - Again, I wasn't too sure what I would need in terms of resistors here either. Since I got a whole bunch of different LEDs with various voltages I knew that I would need a couple different types of resistors, so I just bought a variety pack of 1/2 Watt Carbon Film Resistors (2710306).
I gathered up a soldering gun, solder, needle nose pliers, electrical pliers, some primary wire and electrical tape too since I thought they might be useful.
I know that there are many projects already posted that contain information about how to wire LEDs for simple projects - LED Throwies, LED Beginner Project: Part 2 and 9v LED flashlight - teh best evarrr!, but I think that there could still be some use for a detailed step by step explanation about the basics of LEDs for anyone who could use it.
The first step was to buy some supplies and figure out what I would need to experiment with. For this project I ended up going to Radioshack because its close and a lot of people have access to it - but be warned their prices are really high for this kind of stuff and there are all kinds of low cost places to buy LEDs online.
To light up an LED you need at the very minimum the LED itself and a power supply. From what I have read from other LED instructables wiring in a resistor is almost always a good idea.
If you want to learn about what these materials are check out these wikipedia entries:
LEDs
Power supply
Resistors
Materials:
LEDs - I basically just reached into the drawer at Radioshack and pulled out anything that wasn't more than $1 or $2 per LED. I got:
2760307 5mm Red LED 1.7 V
2760351 5MM Yellow LED 2.1 V
2760036 Flasher Red LED 5 V
2760041 2 Pack Red LED 2.6 V
2760086 Jumbo Red LED 2.4V
Power Supply - I really didn't know what I would need to power them so I bought some 9V batteries and some 1.5V AA's. I figured that would allow me to mix and match and make enough different voltage combinations to make something light up - or at least burn those little suckers out in a puff of smelly plastic smoke.
Resistors - Again, I wasn't too sure what I would need in terms of resistors here either. Since I got a whole bunch of different LEDs with various voltages I knew that I would need a couple different types of resistors, so I just bought a variety pack of 1/2 Watt Carbon Film Resistors (2710306).
I gathered up a soldering gun, solder, needle nose pliers, electrical pliers, some primary wire and electrical tape too since I thought they might be useful.
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https://www.sparkfun.com/products/9547
as are clips that fit onto 9V batteries.
http://www.radioshack.com/product/index.jsp?productId=2062218
For the novice: a "battery holder" is just a plastic box with metal springs inside that push up against the battery terminals, and wires sticking out of the box that you can connect to your electronics project. It's safe to solder to the wires. You can get them in many different sizes (e.g. 2xAA, 4xAA, 8xAA, same for AAA, they make coin cell battery holders...you get the idea) and some have built-in on/off switches which are convenient. The number of batteries you need will depend on your project, but in general battery holders connect the batteries in series, so the voltages of the individual batteries add up. A typical AA or AAA battery you get at a store is 1.5V - so two of them will give you 3V, four will give you 6V, etc.
i had connected 50 leds parallel to 6 volt battery its working without any problem for 5 hours, i didnt use resisters is there any problems
> You should put a resistor in series with each LED as any vdrop differences will result in uneven sharing of the current. (especially as the LEDs age).
However, you can do this anyway. Check the voltage that the LED is rated for. Divide the driving voltage (6V) by the LED rated voltage. Put that many (and perhaps another to ensure that it doesn't over drive the LEDs) in series and that will allow you to have the LEDs light without a resistor. Putting more LEDs will cause them all to dim. The more you put, the dimmer they get.
Thank you very much it has really enabled progress.
Well Done****
I attempted to light up two High power LEDs which connected in series. here are the specs:
. each LED: 2.2 volt 350mA
. power supply: 4.2 volt 500mA
when connected, I see an extreme current drop from 350mA to 60mA!!
COULD YOU PLEASE HELP ME TO IDENTIFY THE CAUSE?
Much regards,
It may have been stated in one one or the comments but it is worth repeating. It is a good idea to check your results after you make your circuit to be sure that you do not exceed 20 milliamps in the circuit. You do this by measuring the voltage across the resistor by the resistor value (ohms).
Thanks,
Lux
how would i power this up?
i tried simply by attaching it to the end of a 12v plugpack but nnothing happened!
PART NO. Chip
Material Emitted Color
Lens Color
AL-B103LRD-004 AlGaAs S/B Red Red Diffused
â Absolute Maximum Ratings at Ta=25â
Parameter Symbol Rating Unit
Forward Current IF 25 mA
Operating Temperature Topr 0 to +70 â
Storage Temperature Tstg -20 to +85 â
Soldering Temperature Tsol 260±5 â
Operating Voltage (Max.) 12 V
Storage Voltage (Max.) 0.5 V
Electrostatic Discharge ESD 1000 V
Reverse Voltage VR 5 V
Just thinking of improvising, using an existing setup, bicycle leds, already in groups of 5, to string a few together, (typically power is via 4 1.2 - 1.5 v batteries) and the chip connection would be cut (no need for flashing function) not sure if smt resistor/s exist in the globule. LEDs look like superbrights possibly 3.2-3.4V at 20 mA. Using 6v source. Would one use one resistor per set or unsolder and include one per led.?
Cheers
I assume from your knowledge that these are five LEDs in series with each other, providing the same ganged 3.2-3.4V drop but five times the light for five times the current - about 100mA total.
In this case, if there are already five in parallel, then they were carefully chosen to have the same (or very close to the same) forward voltage drop, and thus will distribute the current nearly equally. If you were building your own board, the best would be to give each LED a resistor, but if they are already ganged and the LEDs are matched, just figure the single resistor:
E
R = -------
I
R = 3.4V / .1 A
R = 34 ohms (33 ohms is the 5% value)
If there's some other configuration I didn't "get", please let me know.
Thanks in anticipation
Prewired 12V LEDs
High quality LED, soldered to a resistor for 12V (including 12V automotive) use. Strong connections are neatly wrapped with heat shrink and attached to colour coded wire terminating in stripped tinned connections.
Technical Spec
High Power 3mm LEDs - 7000mcd
12V DC
Presoldered Resistor
20 mA
20 cm Wire Length
High Intensity - Low Power 0.36W
Simple to Use
Long Life and Energy Saving
You can do it like this:
+12 ------------------------------------------------------------------
| |
R R
| | o o o as many as you like
led led
| |
gnd ------------------------------------------------------------------
Concerns:
- multiply the current per LED (shown on the specs for each LED, above you say it is .020A) times the number you want (100?) = 2A. Therefore get a power supply that can provide 12V for at least 2A (more is ok). Repeat this formula if the current is different to determine the max ps current needed.
- I wouldn't group a big pile of these RIGHT TOGETHER of in a confined space. Each dissipates .36W (almost all in the resistor), so three or four tightly together (or out of air flow) will be a watt of power, and will start getting a little hot. For this issue, a much better solution would be to create your own LED 'cluster' of series LEDs and a single resistor setting the voltage. If you created 33 sets of three LEDs on the same line with a single custom resistor value to limit to 20mA, then your power dissipation would go way down. This is because the power would go toward light instead of being boiled away in the resistor - resistors just waste!
So this:
12V+ ------- led ------- led ------- led ------- resistor ------- gnd
3.2V 3.2V 3.2V 12v-9.6=2.4V
2.4V /.020A = 120ohms
2.4V x .020A = .048W
Note this dissipates lots less in the resistor. and there are only 33 resistors instead of 100. it uses the voltage much better.
But if you can easily get air to these guys, you'll be fine.
So: in your example above you have a 5V supply, and an LED that uses 20mA at 3V, then the voltage 'left over' across the resistor on any one leg is 2V. 2V/100ohms = .020A (20mA). Thus each leg would correctly function with a 100ohm resistor.
Each leg draws the 20mA as a separate subsystem, as it's own circuit. You should see it as if the + point in the drawing above were two independent batteries. The only limitation would be the maximum current available at the + point... remember that mA are thousandths of Amps, so a power supply rated 1A @ 5V would provide enough power for 50 LEDs... 50 x .020A (20mA) = 1A... batteries can do much better than 1A without much voltage reduction.
I hope this helps you think about this in a way that allows you work with LEDs and resistors in the future. Please reply with any questions or comments.
Sorry I wasn't clear. I was referring to step 8 where he used the 9V and wired the two LEDs in parallel.
R = (9V - 1.7V) / .04A
R = 182.5 Ohms
So in that case it would be a 200ohm resistor for each correct?