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Thread: High Voltage RGB LED COB Using MOFSETS??

  1. #1
    Join Date
    Nov 2018
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    Question High Voltage RGB LED COB Using MOFSETS??

    Im unsure of how to wire between the Arduino and the LED Chips as well as unsure as to which MOFSETS I would need. I know I need a 3 MOFSETS for each LED (One for Red, One for Blue, One for Green) but don't know what model MOFSETS I need. And if they should be P-Channel or N-Channel. First I thought N-Channel but since the RGB LED's have a common Cathode, then I would need P-Channel, right? And if P-Channel, are there any that can handle the higher voltage (24v and 35v) while using the low PWM voltage coming from the Arduino?

    If someone can send me a Fritzing diagram and also let me know what MOFSET I should use and or what resistors I need, it would be greatly appreciated. The Fritzing diagrams are preferred as I am still learning how to read/fully understand electronic schematics.


    The plan is as follows:
    -The 12v power supply would be connected to 2 DC boosters (One that boosts the 12v to 24v for the Red channel and the other that boosts the 12v to 35V for the Green and Blue channels).
    -The higher voltages would then be connected to the source pin on the respective MOFSETs.
    -Then I would have the Arduino PWM pins send the PWM signal to the MOFSET Gate allowing the desired voltage to flow to each color pin on the LED COB.
    -There will be a total of 3 100w RGB LED COBs controlled by the Arduino and the 12v power source.


    So the questions are:
    1. Does this sound correct?
    2. Which MOFSET do I need? (Part number would be awesome!)
    3. Fritzing diagram of wiring. (including wiring of ground wires) and placement of resistors if needed.


    Here are the links to what I have:

    RGB LED COBS: LINK

    12v Power Supply: LINK

    150W Step Up Converter: LINK

  2. #2
    Join Date
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    Default Re: High Voltage RGB LED COB Using MOFSETS??

    Just copy the design of the DC SSR you can find described on the WiKi. There are also a few vendors that sell the QUAD DC SSR. It may have an extra channel but the ease of use (just grab the SSR and go) may be worth it.


    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  3. #3
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    Nov 2018
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    Default Re: High Voltage RGB LED COB Using MOFSETS??

    Been a while since I posted on this project but I still cant seem to get this part working. I have ten 100w COB RGB LED's. I am using 3 Arduino Megas with Vixen to control these along with other lights and relays. I got all of the others working but I cant seem to figure out the 100w RGB's. The RBG's are common cathode so I cut and divided the anode tab into 3 so now each color has its own.

    I have 30 N-Level Mofsets (3 per LED).
    I have four 12v 360 watt power supplies. Each power supply powers three RGB's each.
    The power supplies are connected to Buck Boosters. One bumps the 12v to 24v for (Red) and the other bumps the 12v to 34v (for Green & Blue).
    If you look at the attached picture, this is the wiring pattern I went with for each of the RGB colors. (the buck boosters are not shown in the picture but they would be to the left supplying the voltage to the positive terminals to the LED Chip.) Also the picture shows an Arduino Uno but I am using a Mega and connecting to the 15 different PWM pins available.

    Attachment 41486

    When I run the Vixen sequence, nothing happens. All of the other relays controlling the other lights are working fine but no action on the RGB COBs. Im pretty confident that my code is fine as I had it working on small scale LED diodes so I am leaning towards the problem being with the wiring. Any help would be greatly appreciated. I need to have this working for the 4th of July so I am running out of time.

  4. #4
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    Default Re: High Voltage RGB LED COB Using MOFSETS??

    I must be losing my mind. I figured it out. I had all the COB's wired backwards (cathode/anode). All fixed and now working. I have to run a couple more tests but am pretty sure that all is working now. :-)

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