RGB Led Strip Controller Increase Amps

Thread Starter

JustMe234

Joined Feb 25, 2017
51
Hello.
I have an 7 meters RGB led strip and it consumes around 14.4w/m. I use this controller shown in pic but it can't driver more than 72w.
I have some IRF44n mosfets and i want these mosfets to hold the current not the Controller.
Is it possible to make such i thing?
Thanks.RGBController.jpg
 

Thread Starter

JustMe234

Joined Feb 25, 2017
51
I don't want to use Arduino in this project. I want to make it simple because these leds will be used behind table and mostly will run in yellow color but why not to have all colors and include.
I just open the case and those FETs are really small i can't read what number are on top.
 

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dendad

Joined Feb 20, 2016
3,069
It looks like you could take the FETs off and put bigger one on quite easily.
The tracks may need to have wires soldered onto them for extra current.
 

djsfantasi

Joined Apr 11, 2010
5,683
Just be aware that they may not be MOSFETs. I read the number off the back of them (“2SH8”) and it is very similar to an IGBT series from Hitachi (but didn’t come up with an exact match). So perhaps they are IGBTs
 

Thread Starter

JustMe234

Joined Feb 25, 2017
51
I read the numbers carefully and they are definitely "A2SHB" which in the data sheet are MOSFETs. I'll try to swap one of them with a bigger one as denad said and see what happens.
 

oz93666

Joined Sep 7, 2010
672
mostly will run in yellow color but why not to have all colors and include.
I know the yellow/gold you mean , everybody likes it , many public buildings are illuminated with this colour .... Unfortunately RGB strips do not produce it at all well ... in theory they should produce any shade of any colour , but to get a good yellow/gold , you have to buy yellow strip ...

As for your question ,very rarely will you have all 3 colours full power , often just one full and another half etc ... this probably won't overload the controller ... if nervous put a resistor on the common line this will limit current slightly and you will never notice difference in light output and the strip will have a much longer life if not run at max.
 

Sensacell

Joined Jun 19, 2012
2,449
Before just swapping in a random FET, check what voltage level is being applied to the gates of the existing FETs.
Review the datasheet of the replacement part to determine if the gate voltage is sufficient to turn them on fully.
 

Thread Starter

JustMe234

Joined Feb 25, 2017
51
I know the yellow/gold you mean , everybody likes it , many public buildings are illuminated with this colour .... Unfortunately RGB strips do not produce it at all well ... in theory they should produce any shade of any colour , but to get a good yellow/gold , you have to buy yellow strip ...

As for your question ,very rarely will you have all 3 colours full power , often just one full and another half etc ... this probably won't overload the controller ... if nervous put a resistor on the common line this will limit current slightly and you will never notice difference in light output and the strip will have a much longer life if not run at max.
Its was a hard decision for me to choose Yellow leds or RGB. I go with RGB because i can play with colors sometimes.

You are right only on white color and full brightness those will make controller suffer. But i don't like to run them in full brightness mostly on very low brightness so as you said it will not be a problem.
Thanks for the tip
 

Thread Starter

JustMe234

Joined Feb 25, 2017
51
Before just swapping in a random FET, check what voltage level is being applied to the gates of the existing FETs.
Review the datasheet of the replacement part to determine if the gate voltage is sufficient to turn them on fully.
Good point. Here are details of Gate Threshold Voltage

The A2SHB that is installed has an Vgs = 0.4V min and 1.0V max
the IRLZ44 that i want to install has Vgs = 1.0V min and 2.0V max
 

Sensacell

Joined Jun 19, 2012
2,449
The threshold voltage is where the FET 'just' begins to conduct, a current level of 250 microamps- see datasheet.
The A2SHB has a very low threshold, best to measure that gate voltage!


You can measure the gate voltage with a DMM, set the PWM to 100% and probe the gate to source voltage with the meter.

The IRLZ44 will probably work, but note that the gate capacitance of your new FET is 10X the original, this could lead to slower switching and higher losses.
 

Thread Starter

JustMe234

Joined Feb 25, 2017
51
I connect the led strip to controller set the color to white and brightness to 100%.
With multimeter i connect one probe to Gate and other to Source of FETs i measure 2.62V.

I will try with just one color to swap FETs and see if its works.
 
Each LED color has a different efficiency. In 1964 the amounts of RGB colors for color TVs was 3:6:1. LEDs are completely different since a red LED is only 2V but modern blue and green LEDs are about 3V so produce more light with the same current.

On the internet they say that if two RGB LEDs have identical R and G but slightly different blue wavelengths then the percentages to make white are different.

Which white? Warm white has a pink or yellow look but cool white looks blueish.
 

dendad

Joined Feb 20, 2016
3,069
If you are going to play with electronics, a "Truth Meter" (oscilloscope) is almost a must have device. There are quite a few available now for quite reasonable prices, and many second hand on Ebay.
 
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