Controlling multiple LEDs

Hi all of you! :) My name's Mario and I just registered here since the problem I'm currently facing with my Arduino is driving me totally crazy! I've probably been researching every corner on the internet for the last days trying to find a solution and since I haven't been successful on that task I thought I register myself here and ask the pros :)

Let me explain! I've got 6 bars of acrylic... each stuffed with 12 orange LEDs on a PCB. Now the hard part comes up! Since weeks I'm trying to get them all controlled by the Arduino but I simply cannot manage to do that :( I guess I overestimated myself when it comes to electronic skills... How do I manage to have enough power to get all of them illumiated? I know I have to use a MOSFET but I cannot figure out how to wire it up. Can you guys help me out of that? As far as I know one of the outputs delivers around 40mA. Do I need some kind of external power supply like 12V to hook up too or can I just use the voltage the Arduino provides.

For further explanation: I would like to have some kind of fading glow in every acrylic bar. I'm trying to fade those multiple LEDs on every bar, independently, and at different rates. Guess PWM is the way to go...

Just to give you guys some kind of imagination in what direction I want this project to go :)

Thanks so much in advance and for your time you took reading this! With the best regards from the rainy and stormy south of Austria! Mario

How are the LEDs in the bars wired?

Do you know the LED specifications?

Do you expect the individual LEDs in the bars to fade separately, or the whole bar to fade as one?

How do you want to control the fading patterns?

What else do you want the Arduino to do?

What power supply would you like to use?

Presumably you have an Arduino UNO?

If the Arduino needs to do nothing else, or whatever else it does is quite simple (or can be done while the LEDs are off), then all the PWM can be done easily in software (sketch).

Can we have a photo or two (in perfect focus and no more than 1024 by 768 resolution)?

Hi Paul!

Sorry for being so basic with my provided information :(

  • I connected every 4th of them so basically the LEDs 1,5,9 are one cluster", 2,6,10, etc... Those should be fading in the same way.

  • The only specification I found out are just the voltage which is 1,8V and the max. current is 20mA. Is this sufficient information?

  • Please see answer one :)

  • I would like to have a switch which just turns them off and on, I don't want to change anything by using switches, potentiometers and such...

  • I'd like to use a few 1,2V batteries or one 9V block. Maybe I could use akkupacks with those voltages and have them reloaded on a power supply.

  • I have, yes!

  • Ah, good to know that! Thanks a lot!

  • I will try to get a photo of it but since I haven't got any chance to get back home this weekend it's very unlikely I cannot provide it :( Hope that explanation of me is sufficient to get an imagination how the LEDs are wired up...

I'm off to bed but ...

You unfortunately have not really explained how your LEDs are connected - if you are using a circuit board, it sounds as if they are not able to be changed.

I think you are saying that each bar of 12 LEDs has four clusters, but you have not described just how these clusters are wired. Given three LEDs per cluster, are these three LEDs wired in series (voltage drop 5.4V, a regulated 5V supply would be insufficient)? So you presumably desire the four clusters in each bar to "ripple" in sequence along the bar.

If that is the case, what of the six bars? Should the pattern in each bar be identical or what?

Oh, you really will not need FETs, but if you can get logic level FETs, they would be fine. Ordinary dirt-cheap NPN general-purpose transistors will be entirely sufficient however. For each "channel", you need a resistor (4k7) to feed the base of the transistor from the Arduino, and a resistor in series with each LED cluster to control the LED current. The value of this resistor depends on how many LEDs in series and the supply voltage.

Paul, again I'm so sorry regarding my provided information. I get angry everytime I try to answer a question in a forum where not much information about the problem is posted and in this case I'm not any better... :(

I want to use a PCB to have my LEDs in a fixed position but I haven't designed it yet. Yeah you got it! All the LEDs in every cluster are hooked up parallel in order to have them illuminating at the same amount of brightness. And on top of this the LED-clusters within every full light bar is hooked up parallel too.

Again - YES! The pattern the LEDs should fade should be identical in every single of the bars. But I want to try to have the pattern at different delays on every full 12-LED-light bar. So the first one starts lets say at when the switch is turned on, the second one maybe half a second later and so on.

I'm so thankful for your information for the NPN! :)

You must have a seriese resistor for each LED you can not wire them directly in parallel they will not shair current.

To save on resistors you can wire two LEDs in seriese along with only one resistor. Then parallel up groups like this.

The Original poster also cross posted this to Gigs and collaborations offering to pay for help. I helped and wrote some software as he asked me to do then he shut down his Facebook account and refused to answer any further emails.

@supermaRiio, is @Bainesbunch telling the truth? Did you agree to pay him for work? Work he completed? Are you now reneging on that agreement?