LedWiz Fuses burns

[dreamkey56]

Hi.

In my cab I installed a Ledwiz. Works good to control my Siemens contactors. Now I added 5 CREE 3Watt RGB LEDs. In every Output of the LEDWiz I connected 400mA Fuses.

So, every single cable going to my CREE LEDs is protected by a Fuse.

The common 12 V cable for my LEDs is also Fused. But exatctly this single FUSE burns on some tables.

For example at the blackrose table: At game start, the flasher boards flashes every CREE, but after a short while the FUSE in the 12V burns.

Also a 500mA Fuse burns.

At other tables, like Freddy Nightmare, Bad Cats, Attack From Mars,... they are working very well, over hours. No burnt Fuse.

Did I something wrong? Shouldnt I fuse the 12V? Only the (by the LEDWIZ) switched GND cables maybe?

Or what can be the reason?

My LEDWIZ supply Blocks are connected following: 1 Block with 24V for my contactors, the other 3 Blocks with 12V for the CREE LEDs and (later) other stuff.

Please help!

Thanks!!

[zebulon]

Your 12v fuse is blowing because you are supplying all of the leds with the one 12v line. That means that if all 3 colours were lit at the same time, you would be drawing 3W x 5 = 15w Total. 15W at 12v = 1.25A when you take into account the limiting resistors, that load goes up to 5.25A.

Either way, you should just get rid of the fuse on the 12v. Keep the fuses on the ledwiz outputs and keep them at 500ma or less (400ma should be good for 350ma leds).

[dreamkey56]

Hello Zebulon,

thanks a lot for your answer. Glad, that you help me, as I know, you are THE guy for electronics

Yes, tonight I thought about this Fuse, and I also felt ashamed, because on the 12V wire the single current consumptions will be simple added, because the power supply has to deliver this added consumptions. Know, this was a stupid question, but a simple solution.

Zeb, I posted the Problem with my broken board also. I putted away the (stupid) Fuse in the 12V line, and putted an amperemeter in.

While playing a while, the current consumption seemed to be very low for a few minutes.

But than, jumped to 1,2A, and with my finger I feeled, that one of the 4 Chips on the ledwiz got hot. I pulled cable, but was too late, as it seems.

That means, it brokes, because I have no Output anymore at this chip.

I ordered new Chips, and will Change them. Hopefully, there is no other part also damaged..?

But why did this happen? Was the load too high for the chip? How can I solve this problem?

There is your Booster board - can this solve the Problem?

But it isn´available in Europe, I am afraid?

When the chip was running hot, I only have seen, that one CREE was lighted red, and one green. But I am not sure, if there were any others also lit.

That is not much, I think. Not too much for the ledwiz.

every single output of the LEDwiz was below 400mA, because I putted in every output a 400mA Fuse in. And they are still ok, not burnt.

I am really confused, and dont know, what to do

I think I will use a relay card, to drive the CREEs. So the LEDWiz only has to power the Relais. But I am afraid, that the Relais make the activation of the flasher slow, because of their reaction-time?

And a lot of cabling has to be done

What is also possible maybe:

At the first LEDWiz bank I connected my 24Volt contactors.

What, if a script has a wrong line, that tells the LEDWiz not to Switch the Output at the first bank,

so it Switches the Output to a CREE bank?

So, 24Volts are connected to the CREE by mistake?

In that case, the LEDWiz would be damaged? Or not?

Because: The LEDWiz can handle the 24V, and in the Outputs are the 400mA Fuses. So, they will burn, but the LEDWiz should be still ok, or not?

Please, Zeb, give me a hint:

Any idea, how I should go further, to find the Problem?

Thanks a lot!!

HP

[zebulon]

You don't have to worry about the 24v accidentally getting passed to the 12v bank. Those voltage banks on the ledwiz are only there for completing the path for the clamping diodes built into the uln2803a chips that are on the board, nothing more.

The outputs of the ledwiz sink the circuit to common (or ground if you like) so you'll never have to worry about having too much voltage on the output.

If you are using fuses, are they fast blow, slow blow or normal? This can make a difference with how much amperage they allow past before they pop. When your output is 500ma max and your fuse is rated for 400ma but it is a slo blow, it is possible that the output will blow before the fuse does.

In your case, you are exceeding the maximum power output per chip somehow and that is why the drivers are blowing.

The actual total power output per chip is only 2 Watts total, not 2 Amps.

If you have 8 outputs and each output is running 400ma @12v you are running a total output of way more than 2Watts.

P=E x I where P is power in watts, E is electromotive force in volts an I is current in amps.

In your case:

P= 12v x .4A

P= 4.8W

In the age of the internet it is much easier to use something like this:

http://www.sengpielaudio.com/calculator-ohm.htm

That is the power rating that you are allowing through EACH output of the ledwiz with a 400ma fuse. It's actually a little more complicated than that as you also have resistance involved but the basic gist of it is that at 400ma using 12v you have the potential to draw 2.4 times the total power output of the chip through one output. Multiply that by 8 outputs per driver and it becomes very easy to see why the chips are frying.

My guess is that the specs you are using for the chinese leds are way off from the actual specs of the Cree leds that you are using.

So how do you fix this?

Obviously the specs that you are using for the leds are not the right ones BUT they are working without blowing up so you can leave your resistance values alone (although to be honest, I've yet to come across a RGB led that uses 3 resistors of the same value, usually the value for the red diode is 2x the value of the green and blue).

What you need to do is increase the power handling on the output.

Mechanical relays are not the best solution for this. They don't switch fast enough and if they did, they are mechanical and would wear out rather quickly. The boards I make do take care of this problem, and they are available to Europe (I have shipped to France, Belgium, Germany, Italy, The Netherlands, etc) but the shipping is slightly expensive.

Alternately, you can use constant current drivers that are available on ebay. If you want to get really expensive, you can use solid state relays, also available on ebay.

Increasing the resistance and lowering the current to the leds is an option. This will dim the brightness of the leds, but will lower the demands on the output driver. You could also lower the voltage that you are supplying to the circuit, switch from 12v to 9v and you are lowering the power consumption. Your leds are only using between 2-3v per colour and the rest of the power is being disappated through heat.

The last suggestion would be to edit the settings in the Black Rose file to eliminate the point where the draw exceeds what the output can provide, somewhere in there there is probably a switch that is lighting up the leds at once to make a white light.

[dreamkey56]

Hi Zeb,

thank you for all the Infos.

I wrote a reply, but didnt work, as it seems?

OK, try it again:

I understand, seems the Problem is the high power consumption when more LEDs are flashing together, especially White, where all3 LEDs are flashing at one CREE flasher.

I thought about using mechanical Relais, but not the best idea.

Your Booster board would be the best solution, as it seems. Is it the bare bones Booster board in your shop? Can you guess shipping costs to Austria? Should be the same as to Germany, I think.

Solid state Relais are too expensive.

Constant current supply sounds good to me. So I Keep the resistors like they are now, and put in a current supply in every LED wire? 15 PCs in my case?

Something like this: http://www.ebay.de/itm/121220202740?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

?

Here is the link for the Chinese seller for the LEDs. Maybe I made a mistake, but colour red has different values now..?

I putted 33 Ohm resistors for all LEDS in. Very bad?

http://www.ebay.de/itm/5pcs-3W-RGB-High-Power-LED-Star-3-Watt-Lamp-Light-/181233776079?pt=LH_DefaultDomain_0&hash=item2a325ff5cf

EDIT: Or maybe 15pcs of them? http://www.ebay.de/itm/Elektronisches-Solid-State-Relais-Halbleiterrelais-Weis-/400567989681?pt=Elektromechanische_Bauelemente&hash=item5d43b675b1

Thank you,

HP

[zebulon]

At 12V you should be using 33Ohm 5w resistors for the red diodes and 27ohm 5w resistors for the green and blue.

I could ship you a barebones booster for $65.00CAN including standard airmail shipping (no tracking info, 6-10 day delivery).

The SSRs in your link are for 24-300vac, I wouldn't recommend them. The constant current drivers would work as well.

[dreamkey56]

Hello Zeb,

I am using 33 Ohm 10 Watt Resistors at all colours. So, not correct at the green and blue ones, as it seems..

I will change to 27 Ohms, ok.

Your offer for the board sounds very good to me, thank you.

The board will be connected directly to the LEDwiz outputs?

Is a connection diagram included? Or do you have a link for me?

Do I need anything else to connect it?

Do you accept paypal?

Thanks again,

HP

[zebulon]

Hi HP,

The 10w resistors are an even better choice.....

There are 2 options for connecting to the ledwiz. You can use the included ribbon cable and strip the wires and tighten them down, or you can get the ledwiz adapter for $15 (http://www.zebsboards.com/index.php/feedback-control-devices/ledwiz-adapter-detail) and connect to the booster by a ribbon cable (included with the adapter).

Best way to order is through my site and yes I accept Paypal.

[dreamkey56]

Hi Zeb,

thank you for Infos. In that case, I will order the Adapter too. The easier, the better.

Zeb, I found a mistake I made: I connected some of the CREE Leds to a wrong LEDWiz bank. To the 24V.

What happens in that case?

Very happy today with my cab. Received knocker and Relais, works very well at 24V. BBAAAAM, BBAAAM, really loud. Like it

HP

[dreamkey56]

Hello again. Tryed to order over your shop. But cheapest shipping cost is 20$, and shipping time 1-3 months? Cant choose the offer you made (65 incl. shipping for board). How can I choose it?

THX

[zebulon]

With both pieces the shipping is $19.00CAN for Standard Airmail

I changed the package dimensions in the store so that Standard Airmail should show as an option now (package size was too small).

Don't worry about being connected to the 24v bank, nothing bad happens from that as the connection is internally blocked by the diode in the driver. That circuit only goes live on feedback from an inductive load and leds aren't an inductive load. I would change it over to the correct voltage when you get the chance though.

[dreamkey56]

Hello Zeb.

Isnt working still.

Seems, as your shop doesn't like me

First I putted both articles in my cart,

and then I wanted to choose shipping options. Couldn't see "standard airmal 19 CAN, so I tried to choose the second one (23CAN). But always get an error message "We are sorry, no payment method matches the characteristics of your order".

Now wanted to do again, but now I only see the booster board in may cart. When I want to add the LedWiz Adapter, it jumps automatically to the Cart site, and I can see again only the Booster board in there.

Strange...

will try it again later. At another computer..

HP

[dreamkey56]

Hello again.

Isnt working for me, I am sorry

Woule it be possible, you send me paypal data over pn, so I can do it that way?

Thx

[zebulon]

Hey no problem. I'm not sure what the problem is but no worries. I'll pm you.