Dimming DC led strings

[eelm]

Hi to everyone,

sorry if this is a stupid question but got couple of lights strings that I bought before buying my controller that I would make use of this year if I could fix that issue.

Those light strings have a power converte from AC to DC. They work fine except that of course the fade effect doesn't work. It is either on or off.

Would anyone know if there is something I can do to be able to use the fade effect ?

 

Thanks

 

Seb

[eelm]

or do I have to buy one of those DC controller boards in addition to my actual controller to be able to use those lights as if I understand correctly the controller I have can't do it.

 

Tkx

[kiplorenzo]

Howdy,

 

You could buy a DMX board from Holiday coro... they are about 50 bucks and are a 27 channel controller, but you would need to add in a dongle (DMX King Entec Pro)

or you could look around the forum and see if anyone has a DC board for sale.

[eelm]

Thanks for your reply. I ll look this up

[flyinverted]

Or you could buy an RGB controller (CMB24D-RGB) from LOR. It's 24 channels for 109. It handles 60amps (30 per side) and no need to add DMX to your config.  Later when you upgrade to RGB strips, you'll be ready to go.

[eelm]

Indeed that seems the best option to go for taking into account that I am willing to start using RGB ribbons maybe next year if money and wife allows it.

However the main concern I have is that most of the light strings I have are 36v and this board can only go up to 30v while the DC one can go up to 60v.

It is a very difficult choice to make

What kind of power supplies would you recommend for those boards ? I am a bit confused.

 

Tkx

[rrho170]

If your using regular LED light strings you will likely need to terminate the string with a loading resistor or incandescent lamp. They sell plug in type that just plug into the open female at the end of the string.

 

The issue is the LED's dont load the controller enough to shut of the triacs.  The voltage that leaks is enough to light a string nearly full brightness.

[rrho170]

Those AC LED strings usually have a dropping resistor that take the voltage down to a usable level for the LED's. They do not  rectify, that is convert AC to DC, the LED's are simply flashing rapidly enough to appear on. Move the strings around quickly and you will see the flashes.

[rrho170]

BTW losing 6v is not going to be a big difference once your close to saturation of the LED.

[eelm]

Thanks rrho170 for your answer.

Tried that lamp trick but result is the same.

Been reading several posts regarding that issues and it really seems that I won't be able to use those strings with this controller. Seems that in Europe we have funky stuff not like you unfortunately.

I would then need to go for the DC board, remove the power adaptor and plug them straight on the channel to be able to fade them if I got everything right.

Now there is  also that CMB24D-RGB card that Flyinverted mentionned that would be a smart investment. However if I read correctly it is 30Vdc max and most of my leds strings are 36v so they won't work I think and I will be left with something that can't be used unless I purchase more stuff. And I already spent quite some money this year

I think I ll go for the CMB16D-QC. Just need to figure out the power supplies for it and eventually a case to put it in. I remember seeing a post about this. 2014 is going to be a busy year ))

 

Tkx

 

Seb

[rrho170]

You likely wont notice the 6v loss but finding a straight 30V powersupply may be harder than a 36V Some power supplies have adjustability that may let you drop a few volts OR you can wire in a dropping resistor on each string.

 

My first CMB24D just arrived today. Converting 16 10watt RGB floods for use on it.

 

I didn't notice your location. Differing electrical codes for lighting. Some nations specify no lethal voltages in display lights.