LED Array Help

I need some help with setting up an LED array. It has 440 or 480 lLEDs, I can't remember which, that operate at 2 volts and 35 mA. I want them in 11 or 12 rows of 40. How would I go about soldering them, what power source should I use, what resistance should I use, and is there a way to easily charlieplex that many LEDs? Thank you.

Topic by Ora 11 years ago  |  last reply 10 years ago


Laser detector array?

Hi ladies and gentlemen! I am looking to build a proof of concept, then a prototype on a laser detector array. I need a setup that will pick up a laser beam directed at it from up to 200M away. My idea was to use an array of photovoltaic cells hooked up in pattern. When a laser hit one or more of the cells the current would trip a relay that passed the current to a buzzer or alarm. My concern was that sunlight and ambient refection will cause false signals and trip the alarm. I am sure there is a way to set the system up so that the alarm only went off when there was a voltage spike in a single sensor, or put a variable resistor on it so that only light levels above ambient would set it off. The system will be deployed facing down towards the ground so direct sunlight should never hit the array. I would like to start off with a single photovoltaic cell to prove that the system works and then integrate the others to form the array. Thanks for the help!

Question by KTFlory 7 years ago  |  last reply 7 years ago


is this led array right?

+18V + -|>|- -|>|- -|>|- -|>|- -|>|- -/\/\/\- + R = 22 ohms + -|>|- -|>|- -|>|- -|>|- -|>|- -/\/\/\- + R = 22 ohms + -|>|- -|>|- -|>|- -|>|- -|>|- -/\/\/\- + R = 22 ohms + -|>|- -|>|- -|>|- -|>|- -|>|- -/\/\/\- + R = 22 ohms + -|>|- -|>|- -|>|- -|>|- -|>|- -/\/\/\- + R = 22 ohms this lay out has the resistor on the negative side is this right many thanks for helping karl

Question by kturner6 5 years ago  |  last reply 5 years ago


The leds are getting hot. Help.? Answered

I made this led array as a temporary solution to electricity outage but the leds get quite hot. Is that normal? Is there any better way to make such an array? I have attached pictures. The resistor is 100ohm.

Question by Shariq92 7 years ago  |  last reply 7 years ago


how to make a Pulsed diode array: 810 nm?

I would like to make a Pulsed diode array: 810 nm for my own use, but have not been able to find any schematics on how to do so. Can any one help me in building this unit?

Question by 10 years ago  |  last reply 10 years ago


how can i make a javascript cookie array?

Hello, i am currently programming a shopping cart for my website, which can at the moment go one of two ways 1. everytime an item is added tot he cart, it adds the following variables " " image page url / Name " quantity  Price  + /N " to a variable which is written to the body of the shopping cart  page using document.write, like this example "image" lighter (as url) , 2 , $12 --newline-- this means however users cannot edit shopping cart items once added to cart, nor can they change quantity 2. everything is placed in a cookie array, and is printed like this var cookies +1 set array new item [ cookies] ; name ; quantity ; value and thats that, however i do not know how to make such a long array , or how to make a string printed like that which's values can be read like that, made into a cookie. please help!

Question by oldmanbeefjerky 7 years ago  |  last reply 7 years ago


Rgb matrix, looking for some advice/guidance.?

Hi, its been quite some time since Ive been here. And I still have the same two projects in mind. However, the project im more focused on, is a 32x16 RGB led matrix. Made up of four sections. Im following the project by the two guys over at solderlab.se. They arent very active and speak a different language so their english explanations arent as thorough as Im looking for so I figure id ask the people here :) So, the main questions I have: 1. What kind of material can I use to put the leds on? its like they use thick cardboard or wood. they drill all four holes per led so the legs go through. I want one big board instead of two.  2. What spacing would be good to make it look uniform, yet give enough space to solder?  3. How can I make the 4 controller boards to run it? - They sell them, but they arent cheap. And they dont deliver or sell to the US. So Ill have to make them somehow. I can provide images/part list of what they used.  4. What type of solder/soldering iron would I need? Obviously various temp. But what temps would be safe?  5. What power supply can I use? Ok so, any other info: -They used common anode LED's  -They connect the boards together via ethernet cable.  -They connect the led's together in four sections of 8x16, The anode is connected on each of the 8 rows. And the anodes on all the led's are connected on the 16 rows. If that doesnt make sense, the anodes are connected vertically, and all the cathodes are connected horizontally. -They connect the 48 cathode wires to ribbon cable, that goes to the controller board, same with the anode wires.   -They connect the boards to a Usb to UART connector -Lastly, Part list of one controller board:  HEXFET IRF7314 x4 TLC5940NT x 3 28 Pin IC-Socket 300mil x 4 Resistor SMD 0,25W 1% 10K x 10 Resistor SMD 0,25W 1% 2K2 x 8 Resistor SMD 0,25W 1% 2K x 3 Resistor SMD 0,25W 1% 220R x 2 Resisitor SMD 0,25W 1% 1K x 3 AtMega 328P x 1 74HC138 SMD x 1 Ceramic Capacitor 22pF, 20% x 2 Oscillator 16,0 MHz x 1 Pinheader 2x8 Pitch 2.54mm x 4 Jumper x 3 Pinheader 1x2 Pitch 2,54mm x 7 Modular Jack x 2 Ceramic Capacitor 100N, 20% x 5 Electrolytic Capacitor 680uF x 1 LED 5mm blue x 1 LED 5mm green x 1 Screw terminal 5.08mm x 1 If theres ANY more info required please ask. It said to be as detailed as possible.

Question by 'earl 6 years ago  |  last reply 6 years ago


( Reverse and Array ) .. in Assembly language ? Answered

Hi everyone ! I just started studying the assembly language .. I have this question in my assignment but I'm not sure if my answer is correct I'm afraid that I didn't get the question very well -_- so please help me guys this is the question Use a loop with indirect or indexed addressing to reverse " the elements of an integer array. Do not copy the elements to another array. Use the SIZEOF, TYPE and LENGTHOF operators to make the program. and this is my answer TITLE " question 3 - revese and array" .686 .model flat, stdcall .stack INCLUDE irvine32.inc .DATA                                    array  dword  1, 2, 3, 4 .CODE main PROC mov ecx, 2 mov esi, 3 mov edi, 0 L1:      mov eax, array[esi * type array ]      xchg eax, array[edi]      mov array[esi * lengthof array ], eax       mov edi, type array       mov esi, 2 loop L1 call dumpregs ; check mov eax, array mov ebx, array[4] mov ecx, array[8] mov edx, array[12] call dumpregs exit main ENDP END main waiting for your help  thank you  dreams,,

Question by CSE251 7 years ago  |  last reply 7 years ago


Capacitive Sensor Array Switch

I'm looking to build a on/off switch using an array of capacitive sensors.  To turn the switch on requires a finger swipe in one direction, and off in the opposite.  I will be using an Arduino with capsense as the controller.   How can I detect which direction a finger is moving across the array?  I understand what needs to happen and would research it myself if i knew the terminology behind it.  

Question by buckchuck27 6 years ago  |  last reply 3 years ago


Help wiring an LED array

I'd like to buy some LEDs off ebay and build some LED arrays but I'm confused as to how to wire it. For example, lets say I have 100 watts of LEDs (aka 1 watt x 100 LEDs or 10 watts x 10 LEDs) as an extreme example and each LED has a max voltage of 12 volts. Then lets say I have a power supply that provides 100 watts at 12 volts. How would I wire it? I'm worried that if I hook it up, lots of LEDs will just burn out. Just help me understand what I need to watch out for here. I'm obviously a super novice. Have pity.

Topic by WillE2 4 years ago  |  last reply 4 years ago


Led array proximity switch?

 Hello! im looking for some help, im trying to make one thing similar to this http://4.bp.blogspot.com/_vaK6awHadds/SuTTV4yyT1I/AAAAAAAABV4/sQfemmMEbMA/s400/to_ca_wood_clock_01.jpg But instead of a clock it will say "somewhere only we know", i do not need help with the making per se, but in the electronic part..i hope you can help me My idea is to put some LEDs on the inside so when they light up the words appear magically , and i was wondering if it would be possible to activate/turn on the leds, with a simple touch, using some kind of low pressure button , like the one on the PS3 or in some cellphones..or , to have a proximity switch so that if you were to turn it on , you just had to pass your hand over it...if so, does anyone have any idea how can i accomplish something like this?? thank you in advance =)

Question by esg.827 6 years ago  |  last reply 6 years ago


Individually Addressable Speaker Array

Hey! I had an idea for an array of many small speakers, each capable of playing different sounds so I could dynamically re-arrange which speaker is playing what. This would be paired with some LEDs and some water to make (what I hope will be) a fantastic visual effect. But of course all this is a bit over my head, so I'd like some feedback on my idea! After a bit of research, here's how I think I'll do it: General Concept Essentially what I'm trying to do is make a waveform generator with lots and lots of separate channels. I would hook up my microcontroller to several, multi-channel Digital to Analog Converters (DACs). The microcontroller would feed these DACs signals to generate the wave forms that I want for each individual speaker. The waveforms that the DACs output would each go through an extremely simple amplifier. The amplified signal would go to my speakers. I've attached a diagram that should give you a better idea of what I'm doing. Specifics The microcontrollers I'm looking at are the ChipKIT series from Digilent because I have access to a bunch of these. I'm currently planning on using the uC32, but I actually have access to pretty much all their other boards. The uC32 runs at 80MHz. The DAC I'm looking at is the AD5628 from Analog Devices. That's used in Digilent's PmodDA4, which I also have access to. Alternatively I might just order a bunch. They have 8 analogue outputs, and the SPI communication can run at 50MHz clock speed. I'm planning to have eight of these (for 8^2 total outputs). I haven't figured out what amplifier I'm going to use yet. It'll need to be simple and cheap, as I'm expecting to have 8^2 of them, but I'd also like one that can operate over a large band of frequencies. I've also attached two pictures of the speakers I'm planning to use. I kinda randomly acquired a lot of these, so I'd rather not switch to a different speaker type. According to Wikipedia, the highest note on a piano keyboard is a little over 4kHz. If I split the sinusoidal wave into 16 segments, that means an update frequency of 76kHz. This is way below my max operating speed of 50MHz so I think I can get away with it. Questions What am I doing wrong? I'm hardly an expert on any of this, so I'm certain there's a much simpler way. Are there ICs that do what I want? Maybe something that takes in a digital signal and outputs waveforms? This would be similar to how a servo controller would output different PWM signals, only changing the frequency rather than the duty cycle. What sort of amplifiers should I be looking at? This is my first time on the forum so please let me know if I'm doing anything wrong (or could do anything better).

Topic by JayWeeks 3 years ago  |  last reply 3 years ago


Can anyone suggest a way to make an array of lenses (say 5mm dia - 100 x 100 pieces) on a flat sheet of acrylic? Answered

I have made a simple version - using an acrylic sheet, heating, then pushing down a perforated metal sheet on top to create the 'bumps' Can anyone think of another way?

Question by sParekh 10 years ago  |  last reply 8 years ago


im looking for some help building an ir led array i have 150 10mm IR leds to power, must be from batteries

So which batteries to use? how many leds to connect ? series/parralel? additional resistors?thanks in advence guysmy leds claim to have the following spec:RADIANT INTENSITY 6mW/Sr If=20m/aRADIANT INTENSITY 30 mW/Sr If=100m/aFORWARD VOLTAGE 1.4—1.45vREVERSE CURRENT 10u/a

Question by donnybronson 10 years ago  |  last reply 10 years ago


LED Scrolling Marquee

I am looking for help setting up an LED scrolling Marquee. It has 8 rows and 96 columns. all leds are one color. The only microcontroller I have available is the 8051. any ideas would be great

Topic by Yanks8480 8 years ago  |  last reply 8 years ago


Can I power a LED array with LiPo?

I want to power an led array of 10W LEDs connected in parallel with a LiPo. They are rated 12V and 1050A. So thought of connecting them to 5200mAh LiPo battery so that they all will get 12V and each will get less than 1050A. Can I do like this? Please suggest a cheap method to do this. Thanks Edit1: Thanks for all the answers. 1) The link for LED: http://www.ebay.in/itm/5-PCS-ACTUAL-10W-WHITE-LIGHT-LED-SMD-BEAD-CHIPS-BULB-LIGHT-LAMP-DC-9-12V-/281779856264?_trksid=p2054897.l4275 2)The battery is actually 11.2V not 12V, my bad. 3) I know I have to use individual drivers for all of them but I'm just trying out to find out a cheap alternative. 4) I want to make an array of 10 10W LEDs so thought maybe they will divide the current by themselves.

Question by AlekhK 3 years ago  |  last reply 3 years ago


In PHP 5, is there a limit to the number of keys a single-dimensional array can have? Answered

If so, can this be circumvented by a multi-dimensional array, or does it have the same limit as a single-dimensional?

Question by Padlock 8 years ago  |  last reply 8 years ago


Powering LED array with 12V AC/DC converter?

Hi! Long time lurker here! I have a project in mind that involves the construction of an array of 121 LEDs in an 11x11 configuration. I want to power the LEDs off a 12V AC/DC adapter, but I'm a little unsure about how current works in this case. The adapter is a regulated 12V 1A adapter. The LED array, however, needs only 820 mA. I know the maximum DC current is 30 mA so if the full amp is spread across the 41 parallel series it should be passing ~24 mA through the LEDs. Will this cause any major problems? Is there a way to limit the current to the suggest 20mA? Furthermore, if anyone has any good ideas as to how to mount 121 LEDs in a square grid of inch spacing, I'm all ears. I considered using pegboard, but I can't seem to find any, and veroboard large enough is also proving difficult to source. I don't really have the resources necessary to make my own PCB. Maybe I could drill some pegboard of my own and attach some thin conductive strips for the 12V and 0V rails. Thanks for any help! I've taken a practical electronics course at university and done some soldering (just op-amps and the like), but this is the first real electronics project I've taken on, so any help is greatly appreciated.

Topic by headphoned 10 years ago  |  last reply 8 years ago


I have an array of LED clusters for a big VU meter. How can I distribute power evenly? Answered

Each cluster consists of 6 LED's, and is controlled individualy by an arduino (through a transistor). If I start with normal power, when more LED's light up, they all dim. If I start with extra power, the first few LED clusters blow. I don't want to have a separate power source for each cluster (there are 15)

Question by Stuffses 7 years ago  |  last reply 7 years ago


Arduino programming question: How to multiplex a 16x16 LED matrix array with a Duemilanove?

I have an Arduino Duemilanove and a 16x16 led matrix with no driver IC.  I think I understand the basic hardware principles of multiplexing an array. It should be theoretically possible as long as I use an external system to controll half of the pins. So far I have the hardware about half done. I have some chips set up to sweep through the positive end of the rows of LEDs. I've made this by daisy chaining two 4017s together with two AND gates. This gives me a series of pins that light up by turns up to 16 with some skipped steps at 10 and 16. I got the info from here: http://www.circuitdb.com/circuits/id/154 THE QUESTION IS: Where do I go from here? I'm trying to learn how to program by doing this project. Can I adapt a persistence of vision program to run a matrix? They seem quite similar.

Question by snotty 9 years ago  |  last reply 8 years ago


Arduino and a RFID lock? Answered

I am trying to get the arduino to know when a certain RFID tag has been read.(so it can be used in a lock application) I tried taking the code array variable and seeing if it was equal to the the what showed up in the serial monitor window with the program on the arduino playground page.  But it came up with the error "exponent has no digits" .  So what would I have to use so that the arduino can interpret the "code" array and see if it is equal to a certain tag? I know that there are already door lock programs out there, but I like to know how programs work so I can learn from them and apply that to future projects. Thanks in Advance! AI

Question by JaredsProjects 9 years ago  |  last reply 9 years ago


Resistors on each led? Answered

 I am designing a led array consisting of 17 leds in parallel using 4.5 volt power supply.The led calculator is telling me to use 62 ohm resistor on each - leg of the LEDscould I just use one 62 ohm resistor right after the power supply? Or maybe like 1 or 2 100 ohm resistors? I'm using blue leds 3.3 max voltage 20 Ma

Question by the_burrito_master 8 years ago  |  last reply 8 years ago


How to Wire 12v LED strips to a 12v supply

Can i wire two 12v led strips to a single 12v power supply? I"m attaching a image, since i'm not very good at explaining my self. Thank you

Question by JustXtreme 9 years ago  |  last reply 4 years ago


LED matrix array sink and source? Answered

Looking at  matth3w instructable https://www.instructables.com/id/LED-Umbrella-with-Arduino/ , as a rough guide line for hardware setup, He is just sourcing the rows with MIC2981 driver but has nothing to sink the current except the arduino. Should I also use something to sink the current like a ULN2803 or HEF4794 to protect the arduino if all the LEDs in a column are on?

Question by belliedroot 8 years ago  |  last reply 8 years ago


220v led bulb array delay

I made a makeup mirror with 15 holes for lights, now iwouldlike to have a slight ON delay from one to the other. I was thinking maybe a capacitor after each bulb or just a relay? ( figured the relay kind of has a 0.1 second delay)

Question by turbiny 1 year ago  |  last reply 1 year ago


How to charge a series parallel array?

Hi, we are building an ice cream cart with a 36v sound system and a 12v led dance floor. We desire to do a series-parallel with six 7.2Ah SLA batteries, for the 36v amplifier. And run two 7.2Ah SLA batteries in parallel for the lights.  I would love to brainstorm on how I can charge all these sla batteries. Can people help? We already own a cheap car charger 2 and 6 amp setting.  I am leaning toward throwing a switch or a few switches to go between 36 and 12 for the amps batteries. HELP!!! Thanks, Tor

Question by torclausen 6 years ago  |  last reply 6 years ago


sound-only area and cancellation

I'm looking for advice. (now this is difficult to explain but I'll try my best) I am trying to design a way to have a dance floor in an open area that will have an area where you can hear the music but away from the area it can't be heard. I'm attempting to do this using an array of speakers around the dance floor that will cancel out the music past the dance floor. Each speaker will face away from the area and be equipped with a microphone (directed torwards the main speaker) that then goes through and amplifier and then to the speaker (wired up so that it will emmit an opposing sound wave). This would essentially create a sound barier. I have attatched a picture as a visual aid.

Topic by Sun Gear 6 years ago


diy 110v AC screw-in LED lightbulb?

I'm sort of an electronics newbie, but I'm wondering if anyone knows of any designs to make a 110v AC LED screw-in bulb? It seems all you would need is a full wave bridge rectifier, a resistor(?) to lower the voltage, some LEDs, and some variation on a screw-in base to make a home-made LED bulb. Am I wrong, or shouldn't that be relatively simple to build? Any thoughts? Thanks, Matt

Topic by matthew6 11 years ago  |  last reply 5 years ago


I need help seuencing 6 LED's with Potentiometer on Arduino to have lights move to end of line then return to the start?

OK - I have an arduino duemilanove. I am a novice trying to learn new tricks. I have connected up  a 6 LED chaser with a potentiometer controlling its speed. I don't want the light to go back and forth accross the line of LEDs knightrider style - I have tried this and it works no problem. No instead I want it to go to the end, then return to first LED. Can anyone help me with the code? I have the ASK Manual code which I want to alter for it? this is the ASK manual code that makes the LED chaser move back and forth - what do I need to change / add?  // Create array for LED pins byte ledPin[] = {8, 9, 10, 11, 12, 13}; int ledDelay; // delay between changes int direction = 1; int currentLED = 0; unsigned long changeTime; int potPin = 2;    // select the input pin for the potentiometer void setup() {   // set all pins to output   for (int x=0; x<6; x++) {     pinMode(ledPin[x], OUTPUT); }     changeTime = millis(); } void loop() { // read the value from the pot ledDelay = analogRead(potPin);      // if it has been ledDelay ms since last change   if ((millis() - changeTime) > ledDelay) {     changeLED();     changeTime = millis();   } } void changeLED() {   // turn off all LED's   for (int x=0; x<6; x++) {     digitalWrite(ledPin[x], LOW);   }   // turn on the current LED   digitalWrite(ledPin[currentLED], HIGH);   // increment by the direction value   currentLED += direction;   // change direction if we reach the end   if (currentLED == 5) {direction = -1;}   if (currentLED == 0) {direction = 1;} }

Question by furnacehead 9 years ago  |  last reply 4 years ago


Wiring high power LEDs and need some direction.

Hello all, I am currently trying to design a product, we'll simply call it a light, that requires 6, maybe 7 extremely bright LEDs. I'd like to keep it running off a 3v battery. The LEDs I would like to use are made by Cree (XP-E2) or something similar. The specs can be found on this page:  http://www.cree.com/led-components-and-modules/products/xlamp/discrete-directional/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXPE2.pdf My question is, will I even be able  to fully power 6 of these things off 3V or even 6V(I'd rather keep it to 3V)? If so, how long can I expect the battery life to be? I've never had any experience with these high power LEDs before, but all of the other SMD LEDS only light to ~40 lumens. I'd really like to make this work, or find a similar alternative. Thanks in advance.

Question by bodezia 5 years ago  |  last reply 5 years ago


How to connect several LED arrays together?

I came across a selection of identical LED torches in my house and was wondering if it would be possible to connect them together to make some form of DIY bike light? I was hoping to connect two or four of them together. One of the torches was completely duff so i dismantled it to have a closer look at its innards. They run off 3 AAA batteries, so that's 4.5V each. There are nine LEDs on each array but I can't see any resistors. I think the negative terminal battery pack is connected to the casing of the light as there are solder points on the array that aren't directly connected to any of the LEDs. On the highlighted picture: Red - Positive LED terminal Blue - Negative LED terminal Yellow - Where I believe the +ive LED terminal to conect to the -ive terminal of the battery pack through the casing. If more information is needed, just let me know and I'll see what I can do. Any help you guys and gals could give me will be greatly appreciated, cheers.

Question by atedioussheep 7 years ago  |  last reply 4 years ago


How do I create one array or variable after another in a loop in javascript?

I am currently designing a calculator (https://www.khanacademy.org/cs/calculator/5724205359824896) and I need to create a new array every time an operator (+, - *, /, ^, etc) is pressed. I want the naming to be: var array1[]; var array2[]; var array3[]; var array4[]... etc; and more will be created as I add up the values inside. 

Question by -max- 4 years ago  |  last reply 4 years ago


arrays base address is 1000?.array is a[5][4]..then wat is the correct address of a[4][3]? ?

It's a question on C programming.  Please explain the answer.

Question by sanlee1990 7 years ago  |  last reply 7 years ago


Using Edge-lit LCD's LED array

Hi everyone! Recently, a friend of mine managed to crack the LCD of his laptop. While he got a replacement, I took his old LCD screen apart and salvaged the LED array which edge-lit the screen. Now my question is, is there a way I can power this on? There's no information printed on the LED array about its power requirements and I'm looking for any hints / clues I can get. I've attached a few closeups of the LED array, hope to get a lead on this. Thanks in advance!

Topic by jagtesh 8 years ago  |  last reply 8 years ago


Article: Driving LEDs in Series-Parallel arrays

Found an amazing article on written about the difficulties associated with running LEDs in Series vs. Parallel and Arrays. This answered a few questions I had and I hope it will help you guys out http://www.edn.com/contents/images/6615611.pdf

Topic by John Culbertson 8 years ago


What kind of power supply for this LED array?

Hi, My grow light failed on me recently. It's a series circuit of perhaps 3W diodes.  LED array pic: http://i.imgur.com/YQfJSrZ.jpg There are 18 diodes, and the colors are:  10 x 660nm (red), 3 x 630nm (red), 1 x 610nm (orange), 1 x 520nm (green), 1 x 430nm(blue), 2 x 450nm (blue), Total: 18 pieces Driver: http://i.imgur.com/Fpt2x4q.jpg I'm not really that knowledgeable about electronics, so what specs should I look for when buying a replacement driver? Is it as simple as getting something that is 8-12W like in the image, or is there more to it than that? Thanks.     

Topic by horsebones 2 years ago  |  last reply 2 years ago


Linking 5 battery powered LED arrays?

Let me preface by saying I can do a lot of things myself but have no training in electronics.  If someone can give me a diagram and values for the components I can construct it. I have 5 LED lights which each run off of 3 AAA batteries (3.6 volts).  I would like to take the LED arrays out of all of these and make them into one big light that I could run off the 18 volt batteries from my power tools.  Can I just wire all the lights in series or would I need some regulator circuit to prevent them from burning out?

Question by etcmn 5 years ago  |  last reply 5 years ago


Most Reliable way to wire Led Arrays

I am working on one of my first Led projects. Its a set of tail lights for my Jeep. I have been doing a lot of reading and I am having a very hard time trying to lock down weather I should run them in parallel or in series. Im under the inpression that in series is the most reliable way. Yes? Any help you could give would be great. Jeremy

Topic by returnforservice 8 years ago  |  last reply 8 years ago


How do resistors react in an LED-Array? Answered

Hey guys. I've been reading myself through a lot of articles on websites about how resistors and LED's work, but what I still don't understand is why, when calculating the required resistors for an LED-Array, this website ( http://led.linear1.org/led.wiz ) takes maximum 4 LED's for each resistor at 9V and a diode forward voltage of 2.0 - is it to prevent it become unstable or something like that? And frankly, I think that I miss understand resistors, although I've read a lot of articles about it. So, what I think resistors do is this: Since resistors are used in a simple 1-LED-circuits that has more voltage than the diode forward voltage, it simply lowers the voltage to  the desired forward voltage ( 2.0 for a Red-LED as far as I remember ) - so my point is, when it always is lowered, why would you need more resistors when the voltage is lowered from the first LED on? Perhaps I am very bad at explaining my logical problem here, but I hope that someone actually understands something out of this mess. xS

Question by Zrodo 6 years ago  |  last reply 2 years ago


Simple 5X5 LED array not working. Flickering and high voltage problems, pictures included?

Hello Instructables! I want to make a 5X5 5mm LED array/display looking like this: http://oi44.tinypic.com/wuh3f4.jpg. The information is the following: Source voltage: 12 LED forward voltage: 3.5 LED forward current: 20 (mA)  Total LED's: 25. Resistor value: 270 ohm (closest to needed value) Calculated resistance needed for each vertical row: 20 (mA) x 5 LEDs = 100 (mA) => 100 (mA). Using Ohms law, I found optimal resistance at 120 Ohms. ---------------------------------------------------------------------------- I tried to transfer this circuit onto a stripboard and theres a number of problems: 1: I have to use 24 volts (from a wall charger) for all the LED's to light up. ( Is it possible to make it work with 12 volts? ) 2: The resistors get hot, which I find strange. They are 150 Ohms above recommended level, so it seems strange. 3: The LED's got hot, and burned out even with the above. 4: The LEDs "flickers/flashes" extremely fast, almost not being visible to the eye. This shouldn't happen. ----------------------------------------------------------------------------  What am I doing wrong? Why is this happening? I have tried troubleshooting this for 3 hours and I am giving up.  Thank you in advance, Ardavan. (Ignore the CAP in the real photo. Added as a desperate action after everything self destructed)

Question by ArdavanAbtahi 5 years ago  |  last reply 5 years ago


How can I run a CPU fan from a solar array? How big of an array do I need? This is to move air into a compost bid? Answered

I need to move air through a Compost bin using PVC pipe via a CPU fan powered by a solar array  Thinking 2 " pvc pipe

Question by uthyr 9 years ago  |  last reply 9 years ago


Which cell &amp; how many do I need??

I'm new to this whole electrical engineering thing. Thx to instructables, I got a crash course in LEDs & wiring them up. I need to make a prototype LED array. How do I determine the right size & qty of cells (9v, AA, etc.) needed to run an array for a decent amount of time for an end consumer? What's the equation for figuring this out? Will the Ohm's Law equation (which I'm new to) work for me here? Anyone's help would be greatly appreciated!

Topic by firesurfer 10 years ago  |  last reply 10 years ago


Can the LP3943 source current as well, or only sink it? Answered

The link to the data sheet is here. All it talks about is sinking current, so my guess is yes.  I really wanted to use two of these to get a huge multiplexed array of LEDs, but one of them would need to be able to source the current, can it with the pins set high?  If not, are there other ICs like this that can do so? Thanks!

Question by mojofilta 7 years ago  |  last reply 7 years ago


Does this circuit work in reality?

I have a project (designed in CircuitMaker2000), i wanted to see if it works in real... (track the OUTPUT routes to the 3-inptut gate)

Question by ~CableGuy 6 years ago  |  last reply 6 years ago


Theory, execution and actual construction of a 'Bullet-Shot Location' like system Answered

 How could it be done? I have revised a version using only two microphones that once one of the microphones 'hear'  the sound, a timer will start and will stop once the next microphone 'hears' it.  This would essentially enable you to draw a line straight down the middle of the gun. It would also allow for tracking the location in real-time. How could you physically build it for a cheap set-up. I'll upload a couple of diagrams some time.

Question by Lance Mt. 9 years ago  |  last reply 9 years ago


Need some help with a parts list for a RGB array.?

Im saving up money to build a wall of 512 RGB LED's from a site called solderlab, and they provide real good documentation, and pics, but im still confused on what I need EXACTLY for the PCB boards. There will be 8 with shift registers, and one for power. I will link pictures to the schematics, renders of the boards. And Ive got some, I think. Also where I can get the custom PCB's made, and or, how much they will be! :D  Heres the Power board:  http://www.solderlab.de/images/led-projects/modular-plasma-wall/Mainboard_PCB.png Render of the Power board:  http://www.solderlab.de/images/led-projects/modular-plasma-wall/Mainbord_Top_1.png One of the 8 Shift register boards: http://www.solderlab.de/images/led-projects/modular-plasma-wall/Segment_PCB.png And lastly, The render of The shift register boards: http://www.solderlab.de/images/led-projects/modular-plasma-wall/595_8x8_Top_1.png And as far as I can tell, I need: 36 RJ45 Jacks 32 Shift register 74HC595's base resistors 10k Conrad Electronics 64 npn-transitors BD139 Conrad Electronics 64 34 pin ribbon cable connector 3- 22p ceramic caps And they say ( but im not sure what or where to get them) Pull-Up / Pull-Down resistors 10k     x5 4 x pin header quarz 16MHz (Im assuming this is just a 16 mhz crystal. And two Electr. Caps 100 µF So what am I missing? and how do I make/get those little wire bridges? Thanks! :D Im excited.

Question by 'earl 6 years ago  |  last reply 6 years ago


Mixing different colored LEDs in series-parallel arrays

I've been doing lots of research, both on other internet sites and the LED projects posted here, but can't find out how to mix colours in LED displays. My plan is to build better Christmas displays from LEDs than the rope light ones you can buy. I've found out how to drive LEDs from a power supply both in series and parallel, with a current limiting resistor. What no one seems to discuss though is driving sets of LEDs off the one power supply where they use different coloured LEDs of different voltages. If I want to wire up lots of red LEDs (2.0V drop) in series and some green LEDs (3.3V drop) in series for example, can I just wire the two sets in parallel to each other (assuming both sets of LEDs in series don't require more voltage than the power supply? Thanks!!!

Topic by FutureCow 10 years ago  |  last reply 10 years ago


How should I modify these code to send sensor reading to another Arduino?

Idea is to make a weather station using two Arduinos. They would communicate using RF transmitter and receiver. I tried to use VirtualWire library and its examples (named transmitter and receiver). I can send and print characters but I can't do the same with number(positive and negative). It's going to send temperature (both positive and negative) and barometer readings. In my opinion I should send them in an array (int).  How can make this work? Is there a better option for wireless communication? Thanks

Question by DavidC1165 1 year ago  |  last reply 1 year ago


How do I power a 9v LED array with a Miller Solar Engine?

Hi there! I'm a complete electronics newbie. I'd like to know if it is possible to power a 9v LED Array by way of a Miller Solar Engine that uses a 6.7v Solar Cell. I'm attempting a similar project to this... https://www.instructables.com/id/Give-the-gift-of-Robot-Invasion/ With the main difference being that I'm going to have two little robots, one holding the solar cell and one holding an LED array! The idea is that the solar cell would charge a capacitor that would then occasionally power the LED array. I dont even know if this is possible, i'd appreciate your help! Thanks.

Question by garywright87 9 years ago  |  last reply 9 years ago


I need help with a LED array Plan. help out?

I want to make a 512 LED array, controlled by a arduino.  Basicly, Im going for a 32 bank audio spectrum analyzer.  The bottom up, will be blue. The first thirty rows. Then the top two rows will be red.  I have NO idea how to make that work. Or what I'd need besides led's.  I was hoping to make the input just come from a ipod. so I could plug in a two way splitter into the ipod and plug the array in, and the other into a speaker. so you can hear the music of course.  I got the inspiration from this youtube video. thats what I wanna make, But with a arduino telling it what to do.  http://www.youtube.com/watch?v=LIOUXr9v2RI&feature;=related Thats where Im at so far. So any help would be greatly appreciated :D

Question by 'earl 7 years ago  |  last reply 7 years ago