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DIY LED Molefay


fliggygeek

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Hi all,

 

I have endeavoured to start a project to build LED molefays. I am using 30w LED modules, and will have a separate power supply for each of them. My basic design is a 4 way square/line, and I figure that because I am using separate power supplies, I will be able to make these more or less modular. My only issue there is controlling the power output. I am (obviously) going to use DMX as the external control. My main question is: Does each device on DMX trim out the data that pertains to its set of addresses? To expand on that, lets say I have a 12 channel dimmer on a DMX line. it uses channels 1 thru 12. When I connect to the DMX output of the dimmer (Daisy Chain Style) will I be able to see the DMX values for 1-12 (and potentially have two sets of dimmers on identical addresses)? Also if you have any ideas spring to mind please comment, I want to hear what you have to say.

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DMX is 512 bytes in a row no matter where you see it on the cable, whether its after 30 fixtures or coming straight out of the desk. A fixture is a passive device, and the DMX in and DMX out connectors are connected together directly inside. If the fixture is off, then everything else down the line will still work. If you reorder the fixtures on the DMX line but keep the addresses, then it'll still work.

 

As you mention, this will let you have two or more fixtures using the same address. Useful if your desk can't support enough channels, and you need to hard patch the devices to the same addresses.

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You mentioned dimmers in your post : I hope you realise that you won't be able to use a normal dimmer to control your leds? You're going to need some form of PWM dimming to control them.

 

If you are handy with a soldering iron, you could always use my PWM LED source code and schematics which I posted ages ago. You'd only need one PWM channel to control your LEDs, and the MOSFETs would need a heatsink to handle that much curent.

 

Or an easier option would be to use one of Milford Instruments 4-channel LED driver boards.

 

Hope this helps

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Really want current drivers rather than voltage drive, then use PWM to control the buck switch mode.

 

Running large arrays in voltage drive isn`t very stable and is liable to result in short LED life.

 

The system I am making will be Current controlled, I have some constant current power supplies in mind, and will be makign a variable current system that communicates with some sort of serial data stream. The way I look at it is that I can make a DMX to simple serial converter and just feed that stream to the set of LED modules, that way I can have up to 512 of them on a single DMX chain without having to conform to the max of 32 devices per chain. I can then make a small control unit that can set the starting channel and then converts the DMX to serial or some sort of CAN bus. This way I will be able to use as many modules or as few modules as I want, leaving the DMX out to feed any other devices on the chain.

 

You mentioned dimmers in your post : I hope you realise that you won't be able to use a normal dimmer to control your leds? You're going to need some form of PWM dimming to control them.

 

I do realise this, and yes its a trap for young players. I intend to use current control on the circuit, as to how that works I have yet to work out. I was considering using the Milford led driver, but its issue is that I need to control 16-18 volts at about 0-2000mA and wish to be able to make my own dimming curve to normalise the LED response to conform to the rough intensity/power of a standard Molefay.

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im trying to make samething and found this card ,http://www.aliexpress.com/fm-store/701799/209915969-378111925/Easy-DMX-LED-controller-DMX-decoder-driver.html its 9 pixel rgb card or you can use it as 27 single outputs, outputs are max 1A for each but if you can find someone to modify the outputs it can handle much more, and you dont need several power supplys , you should think the weight also, and its constant current output...
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Ok, so for an update/clarification. These devices will be using a similar size LED array to this one:

http://www.ledwt.com/images/LED%2030W.jpg

 

in the interests of long lamp life, I will be using a separate constant current for each LED. Not only does this mean I can perfectly regulate the power in each LED unit, it also means I can make the power supply and LED into a module, get 4 such modules, arrange them how you will and add a controller and you have a standalone highly flexible light system. Add coloured modules and you have even better options. So, to make this happen, I will be making for a start, 4 LED + Power Supply units and one DMX controller. I will experiment with them and see what happens. I can buy the power supplies for about AUD$13 and the LEDs for about AUD$24 (White) so with a heatsink system, possibly a fan based one, and a frame and DMX controller, each module will be <$300 with Controller. Hopefully.

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