40W RGB DMX Reciever Controller.. PLEASE HELP A NEWBIE !

[mrfunk]

Hi, Newbie Here.. PLEASE be gentle !

Been asked to commision some very specialist lights, connected to a unique fountain system.. This really is going to be stunning!

Basicall a 3/4 colour 40W rgb LED connected to fibre then to a fountain.

I need to drive the LED via a STANDARD lighting desk running normal DMX.

The leds work at say approx 10V at 10W per colour chip.

So I guess Im looking at a 4 channel controller..

What do you guys suggest?

Im probably will be doing quite a few of these and quite happy with PCB design.

Not to keen on programming.

Is there an off the shelf KIT.. Im UK based, but dont mind importing.

Cost and simplicity are KEY

Appreciate any help in the right direction.

David.

PS I tried the search but get an error, so please dont add the traditional remarks that people tend to attack newbies with.. thanks

[Entropy]

Search is indeed broken - we tend not to be too big on the "use search" flames here.

However, the current requirements for such high-power LEDs makes things... Interesting. Do the LED modules include a constant current driver, or are these bare chips?

If you want to drive bare chips, you'll probably need a good constant current switching regulator like the National Semiconductor LM3404HV.

That regulator does have a PWM dimming input, which could probably be driven by one of many DMX projects here.

Do keep in mind that, at least the way you described it, this is a commercial project and people who solicit information here to drive a commercial product without feeding things back (e.g. PCB designs of the product and such) are frowned upon.

[DynamoBen]

Are you looking for something you can buy "off-the-shelf", or build yourself?

[mrfunk]

OK many thanks for your replis.

Basically this fountain system will be hired out with an operator for special events.. It wont be sold, as the idea and application are unique, and its best to kep it thiss way.

any info on this project WILL be shared so please be rest assured..

OK Im looking to use this LED http://gb.mouser.com/ProductDetail/LedEngin/LZC-A0MA40/?qs=sGAEpiMZZMsgllGlynFdfsYY1VIASIDnp5239iG2ViA%3d

I like the idea of the LM3404.... would like to know where to start looking to drive the PDM input from DMX. As this is key. So hence we should be able to get some blocks together


If it was a low price we would look to buy a solution.. but like the DIY route, as we have done with our fountain design.


Really appreciate your help with this project, and IM sure you will be impressed with the application, once constructed.
many thanks

David

[Entropy]

OK, I've seen those modules. Yes, they will need a good constant current driver, probably the LM3404.

As to going from DMX to PWM - A critical question here is what the max PWM frequency into the LM3404 is. (I don't have time at the moment to look this up.)

If it is compatible with the PWM outputs from a PCA9635, then you can use a PCA9635 for the PWM, and drive it with an AVR acting as a DMX-to-I2C bridge, see https://github.com/Entropy512/DMX_PCA9635

If the PCA9635's output PWM is too high frequency, you can probably do software PWM within an AVR. My github page above has the two most critical parts of this (a softpwm implementation, and a DMX receiver implementation), but they are in two different projects. "gluing" those two software components together shouldn't be too hard.

[pmscientist]

Looks like the 3404 can do 1MHz, and possibly higher frequencies. That should work with most, and maybe all, of the common DIY platforms.

The good news regarding platform is you have lots of DIY options.

Since you're not looking to do much programming, it may be possible to base your project off something like a Renard64 running the DMX firmware and using modified DC SSRs (http://doityourselfchristmas.com/wiki/index.php?title=4_Channel_DCSSR_Assembly_Instructi ons). It seems possible to essentially replace the MOSFET from the DC SSR with the 3404. Since that part of the circuit you'd have to design yourself regardless of platform, that would let you focus on hardware design and not worry about software.

The PropController project discussed elsewhere here might be a also be a good platform, and uses the same SSRs as Renard. It's still in development, but dev boards are available. If customization becomes a need, it's probably easier to modify the software for that than for the Renard, but it is a somewhat new project, and thus isn't as well documented yet. There are both RS485 and ethernet/E1.31 versions though, so if ethernet based DMX is of interest, that would be a good platform.

Depending on how many channels you need, AVR does 8 bit/256 level PWM in hardware. The ATmega168 and siblings have 6 or 8 channels, depending on the package. The Atmega2560 and siblings have 14 channels. Software PWM is also doable with an AVR, ATmel actually has example code for doing so.

If you decide you want or need software that's more customized, the Arduino platform Entropy is using is a good way to go, and can be sourced from the EU, there's probably a UK distributor. Here are a couple more links to AVR/Arduino based DMX info/projects. Between the various Arduino projects, you should be able to minimize the amount of coding to a good degree.

The base Arduino project is here: http://www.arduino.cc/playground/DMX/DMXShield
Another DMX library is here: http://code.google.com/p/tinkerit/wiki/DmxSimple
A basic example project is here: http://www.tasankokaiku.com/jarse/?p=268

[aussiephil]

OK many thanks for your replis.

Basically this fountain system will be hired out with an operator for special events.. It wont be sold, as the idea and application are unique, and its best to kep it thiss way.

any info on this project WILL be shared so please be rest assured..

OK Im looking to use this LED http://gb.mouser.com/ProductDetail/LedEngin/LZC-A0MA40/?qs=sGAEpiMZZMsgllGlynFdfsYY1VIASIDnp5239iG2ViA%3d

I like the idea of the LM3404.... would like to know where to start looking to drive the PDM input from DMX. As this is key. So hence we should be able to get some blocks together


If it was a low price we would look to buy a solution.. but like the DIY route, as we have done with our fountain design.


Really appreciate your help with this project, and IM sure you will be impressed with the application, once constructed.
many thanks

David

David

The LM3404 is just one option and not a bad one at that but will require some very careful reading of the datasheet to ensure that you get the PCB layout and component selection spot on with the different colours requiring different components around the lm3404.
Switch Mode constant current design need careful layouts.

From the Datasheet
Dimming frequency,
fDIM, and duty cycle, DDIM, are limited by the LED current rise time and fall time and the delay from activation of the DIM pin to the response of the internal power MOSFET. In general, fDIM should be at least one order of magnitude lower than the steady state switching frequency in order to prevent aliasing.
----------
In english even though the 3404 supports steady state freq up to 1Mhz for efficiency reason you may chose a lower value. being conservative and setting fDim at 10% of switching frequency then for 1Mhz you can have fDim up to 100khz, inside all the current DIY projects, however at lower frequencies you may run into issues with projects that use 97khz LED controller chips.

Cheers
Aussiephil