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mini 3ch RGB controllers

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by sjim, Jan 27, 2013.

  1. sjim

    sjim New Elf

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    <blockquote>They have these mini 3 channel RGB controllers with the premade program modes for the LED strips, capable up to 12amp (3*4a per ch). Should I be able to use these with 3w RGB modules (350ma)? so, it's non-dmx controller, but, must use pwm for programmed modes. </blockquote>
     
  2. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    If the modules are dumb modules just like the strip then yes. Some links to what your talking about will confirm this.
     
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    sjim

    sjim New Elf

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    yes, they are dumb... no DMX, so really, it's just a matter of not overloading the controller. The 3w RGB are max of .350a per ch, so little over 1a with all on. With the controller handling 12a, I figure I can wire 10 of the RGB modules together with a single controller be ok. The controllers are only $2 bucks plus on ebay that's super price, basically, has all the functionality as the 24 key IR remote 3ch controllers you see.
     
  4. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    If you are running an LED by itself then YES & NO, thats why i asked for the link as waht you have described is not very clear and a link to what you are wanting to use will help.

    If just single 3 watt LEDs you are wanting to use then you need to design a circuit with a current limiting resistor to use that controller. You can design the correct circuit and resistance value by going here

    BUT, this is not the best method for controlling high current LEDs, what you need is a constant current driver as this is the best method for controlling LEDs because LEDs are current driven devices, so controlling current is the most important factor. This will ensure you have the correct current at all times unless the voltage drops below the value that the constant current driver can maintain that current and will ensure your LEDs will run reliably.
     
  5. OP
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    sjim

    sjim New Elf

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  6. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    That controller wont do unless you make up an LED circuit that matches the voltage and has a resistor that will match the current needed to drive that LED circuit.
     
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    sjim

    sjim New Elf

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    darnit, ok...be ignorant here, so, the RGB's in the led strips are different than say single 3w RGBs..etc. So each RGB would need it's own board and resistors?
     
  8. David_AVD

    David_AVD Bite my shiny metal ass!

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    I agree with Eddy. Those 3W bare LEDs will need a constant current driver. You can't just hang them on the output of a standard DC controller.

    Using series resistors with high power LEDs is not really practical either. You want a constant current driver.

    As an aside, I'd be surprised if that controller can really handle 4 Amps per channel. 12 Amps on the input cable and the output common pin seems rather unlikely.
     
  9. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    How do you plan on using these LEDs, are you planning on using them for flood lighting and do you plan to use more than one per controller? This will give us an idea on what may be the best suiting controller to drive these LEDs
     
  10. OP
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    sjim

    sjim New Elf

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    Ah, ... I'm starting to understand I think. The mini 3 channel dmx controller I found is with (mainly) for the LED strip lighing like 5050 SMD's something like the 150/300 chip strips, which case are really dumb strips and just run preprogramed modes. So, these SMD's leds are very different from say the star 3w RGB's ? I was thinking they were similiar, just brighter using more current and why couldn't this mini controller and reasons why it couldn't work with the 3 watt stars (really just 3*1watt RGBs) . In reviewing, am I failing to understand the difference between 2 types of LEDs? In looking over the mini-controller, doesn't it appear to have limiting current abilities since it can control daisy chained LED RGB strips. I know I'm probably mis-understanding but that's what DIYer is about (lol). (I believe the 3 ch mini RGB controllers use PWM to run the program modes)

    part 2: I'd like to build an wash flood bar with 6 starts per fixture that's non-dmx but could use the 3 channel
    mini controllers that the LED SMD strips use (is this possible) and what components are needed. There has to be some kinda of standardized procedure/process I could do to do this pretty straight forward.

    part 3: Then I was thinking, if I wanted to convert them to DMX addressible fixtures I could use holidaycoro's 3 channel dmx controller rated at 6amps see link here, believe folks are using these with the 10w RGB floods that Ray Wu is selling.

    http://www.holidaycoro.com/3-Channel-DMX-RGB-Controller-p/26.htm
     
  11. David_AVD

    David_AVD Bite my shiny metal ass!

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    Lower power bare LEDs can use a simple series resistor. High power bare LEDs require either a big resistor (of critical value) or a constant current driver. Driving high power bare LEDs (such as the "star" type you mention) incorrectly will see them them die quickly due to voltage and (LED) temperature variations.

    You can buy DMX controlled high power RGB LED bars for quite reasonable money these days. They have all the constant current electronics built in. It's not really viable to make your own unless you have very specific size and shape requirements.

    If you're still keen to use your own LEDs, maybe buy some DMX controllers with constant current outputs. I'm fairly sure Ray Wu has these too.

    I have a few of the 10W RGB floods from Ray Wu. They are the DMX variety so all you need is 12V and a DMX signal.
     
  12. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    So the basic rule with LED circuits

    Series LEDs = voltage is added together

    Parrallel LEDs = current is added together
    So by having 3 LEDs in series you would then add the voltages together, 3.5v + 3.5v + 3.5v = 10.5v so you would have to drop the voltage by 1.5 volts for the circuit


    So the LED you are looking at will have some specifications, these are important for correct circuit design. The below specs are for the 3 Watt RGB LED you linked to

    3 Watt RGB LED
    DC forward Current = 350mA
    DC forward Voltage = RED - 2.5v, GREEN & BLUE - 3.6volts

    So each colour is 350mA but they require slightly different voltages to run correctly. You plan to use 6 LEDs per fitting and I believe you also plan to use 12vdc.

    So lets take a look at the LED circuit you would require to design to run 6 x 3watt RGB LEDs at 12VDC
    GREEN & BLUE

    So by having 3 GREEN or BLUE LEDs in series you would then add the voltages together, 3.6v + 3.6v + 3.6v = 10.8v so you would have to drop the voltage by 1.2 volts for the circuit

    [attachimg=1]

    As you can see GREEN & BLUE colour you may be able to get away with it but when using the RED colour its a bit different

    So by having 3 RED LEDs in series you would then add the voltages together, 2.5v + 2.5v + 2.5v = 7.5v so you would have to drop the voltage by 4.5 volts for the circuit

    [attachimg=2]

    As you can see trying to achieve the RED colour will be difficult as you will need a decent resistor due for the amount of voltage you need to drop to make the RED circuit. This will also build up lots of heat within your enclosure as you are disappating around 3.5 watts just through the resistors.

    So with high current/wattage LEDs if you dont use the constant current method then your design will not have a long life and i would expect that the red colour would be first to go. Remember that resistors have a tolerance value and the actual value of the resistor can vary which in turn can cause issue when running high current LEDs. The higher the current the more critical the resistor value.

    Now with constant current the current is maintained to drive the LEDs and as already suggested is the best way to drive these LEDs, you can try and do it the other way to save a buck but in the end you will be paying more because of the expected failures you will get. These days its a cheaper outcome to just buy some floods already made instead of trying to build your own.
     

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  13. OP
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    sjim

    sjim New Elf

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    Thankyou, ok, SMD strips = series leds, 3w Star = parallel leds. So the mini 3ch controller is simply not made to manage current but rather voltage more less on the strip leds. But, if I manage the dissipation it's possible I could use either controller or holidaycoro's dmx driver. I really appreciate your help, it makes sense now. Could I just use a single constant current driver on the RED only? and then resistors on the others... this would be fast cheap way I'd think. Yeah, I know the prices are very reasonable now, but, I already ordered 20 of the 3w RGBs, so, probably see if I can make 4 fixtures using 5 RGBs per. I suppose to using larger heatsinks would help the situation.
     
  14. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    The same theory applies to both strips and 3 watt leds, the difference is in the current required, As the drawings below show is 3 x 3 watt LEDs in series.
    Example is the difference between a dumb RGB strip and an intelligent RGB strip, both use the exact same LEDs but dumb RGB is powered by voltage control as there is a current limiting resistor, so for 12vdc strip you have 3 LEDs in series, now the same thing applied with 12vdc intelligent strip , still the same LEDs and still 3 LEDs in series but most intelligent pixel chips are current controlled so they instead control the LED by current control. Remember LEDs are current devices and by using a voltage control you are controlling voltage to maintain the current as this is all part of Ohms law and current, voltage and resistance have a direct relationship so voltage drop, different values or resistance, voltage spikes and other variables will have an effect on the outcome. So by controlling current instead of voltage then these variables are mainly eliminated as long as the voltage is high enough then the current will always be maintained. The higher the wattage LED the more pronounced any of these variables will become when using voltage control.
     
  15. OP
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    sjim

    sjim New Elf

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    Re: 3w RGB star / RGB controllers

    how many constant current drivers would I need for a 6 star RGB bar? one for each RGB led, then 6. Any recommendations for drivers.... would it need to be 350a or 1050a
     

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