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Found amazing cheap RGB led boards, need help changing out 3 individual LEDS for a single RGB LED? Answered

I have been looking for a cheap board to control normal 4 pin RGB LEDS, and I finally found one! However, this board has 3 individual LEDS a red, green, and blue LED and I need to change them to have a single RGB LED. This board has 7 colors, red, green, blue, yellow, aqua, purple, and white. The problem I am having is, when I hook up the single RGB led the blended colors do not work anymore. Even though it's on aqua it still only looks blue, or if it's on yellow it only appears red. I only get the 3 main colors Red, green and blue when I hook up the single RGB led vs the separate 3 LEDS that comes standard on this board. Hoping someone can help me figure out why the blended colors aren't working when I switch to the single RGB led.

I uploaded a photo of the board, and the single RGB led on the bottom left I am trying to replace the 3 LEDS


Most RGB LED's I had use a common negative line - your circuit uses 3 negative lines for 3 LED's.
Also it seems ou totally bridged the resistors for the LED's - you should never run a LED without a suitable resistor.
If your LED is common ground and not common positive it won't work as planned.
You would have to replace the existing LED's with transistors to switch your RGB one.

My single RGB LED is common positive. And I bridged the resistors so I could hopefully run more then one RGB led off this board. I'd like to run between 5-10 LEDS. The resistors will be in line to each led in stead of the board.

Ok, your LED matches the the circuit, that is a good thing.
Still the resistors are required to limit the current to the LED.
So you need to know what voltage comes out of the circuit and selece the resistor according to this and the nominial voltage of the LED.
You can only run more LED's if the circuit can actually handle it, those chips are not really designed for a lot of power.
Assuming the original LED are low current and you add 5 instead of 1 the chip has to provide at least 5 times the power it was designed for.
You don't store a 600kg engine on a shelf rated for a max of 300kg, do you? ;)

Do you know what kind of circuit this would be called? I would even pay for someone to make custom boards like these that can handle a little more power. All I want is to be able to have 7 colors that are controlled by a momentary button, which is what this circuit does. This is the only board I have found (Under $5) which I could even get to work at all with the simple 4 pins LEDS I want to use.

I have used that controller a lot for LED strips. But those wont work for my needs, I need a very compact size board that can run off a single 3.7-4.2v. That's why I am trying to make the boards I have work.


3 years ago

So, are there more available for me to buy ?

I don't get them from a public website, I got these from a manufacturer who use them in toys. But if you want any I could sell you some. Assuming it's not against the rules here.

Since you have gotten the RGB to light then we don't need to cover how to hook it up. The problem your having has to do with the colors and intensity of the onboard LEDs versus your RGB. The PWM signal being used is set for the LEDs on the board. Your RGB will require the signal to be slightly different to give accurate colors beyond that of the native red, blue, and green. Best thing you can do is compare the intensity of the red, green, and blue of your RGB. If one seems to be brighter then the others add a resistor. try to get all 3 balanced out. If that doesn't help then there is nothing else you can do. The board was speced with certain LEDs in mind.

Just be sure to desolder the existing LEDs before trying anything. If you where testing the RGB with the original LEDs still in place this was messing with your results.