Hello,
I started a project in which I control an 24v LED strip.
My problem is that after a while when I turn the strip to it's maximum, it flickers slightly and irregularly. I can"t seem to find why it's happening.
I have a 24V 5A power supply, the strip consumes 4A maximum.
Here's the schematic.
Hope you can help me.
You should always include a large capacitor, about 1,000 uF across the power and ground of the strip physically on the strip or as close as possible.
Is this an RGB strip, if so do you have three FETs or just the one?
It's a white only strip.
Ok for the capacitor.
I have a module from amazon with IRF520 and I don't have this problem, also without capacitor.
Does my voltage divider in input of A2 can damage my arduino (I don't think because It's 5V a the input) ?
Thank you
What are S+/S- for?
Does my voltage divider in input of A2 can damage my arduino
I can’t see any voltage divider or A2 on that schematic.
Grumpy_Mike:
I can’t see any voltage divider or A2 on that schematic.
Can you see R5 and R6?
Yes it's in the bottom right corner.
S+ and S- is a security, like a switch. The LEDs can turn on only when A0 is low.
oh sh...t for R5 and R6, you're right...
So add a large capacitor, invert R5 and R6, add a 220R resistor between Arduino and transistor
Thank you a lot.
Grumpy_Mike:
You should always include a large capacitor, about 1,000 uF across the power and ground of the strip physically on the strip or as close as possible.
No, it is not an "addressable" strip and you should absolutely not put a capacitor across it as you are trying to PWM it.
The pull-down resistor on the FET is unnecessarily low. It should be 10k or even 47k. Its only purpose is to hold the FET off until the Arduino starts its program. A 220 Ohm resistor between the Arduino output pin - which where you connect the 10k or so - and the FET gate is a good idea.
Ok thank you, I add this to my schematic. I put 1k resistor because it's like that on the Chinese amazon one, but ok for 10k or 47k if it's better.
Hello, I tried to put my transistor on the Chinese module. It's the same problem, LEDs are not at maximum brightness, and flicker. My transistor is an IRF520N and the one used on the Chinese module an IRF520, from what I understand mine is an N channel and not the other. So I have to connect R1 to 5V and not to GND?
I don't know about the flicker, but you say the LED strip requires 4 Amps. The IRF520 is not a logic level device and will not actually turn on to any useful degree at 5 Volts. The FET will be getting very hot if you are attempting to use it.
You need one of these modules.
Thank you for your answer. I am trying to create my own pcb (discouraged considering the price of these modules). I cannot find these MOSFETs on my website (RS-online).
What would be the most suitable MOSFET knowing that the strip is on only for 1seconds every 30 seconds?
Any logic level N-channel FET that has a logic level input. You find out if it is a logic level input by looking at the data sheet. Ignore the gate threshold voltage you want to look at the source drain resistance. Beside that figure will be a test condition. If that shows 10 V it is not a logic level input. It should show 5V or under for it to be a logic level FET.
knowing that the strip is on only for 1seconds every 30 seconds?
Not very relevant but you say it is flickering, can you see the flickering at only one second?
TheGrandWizard:
Thank you for your answer. I am trying to create my own PCB (discouraged considering the price of these modules).
The modules I cited would be significantly cheaper than making your own PCB and finding the matching parts, so I am not sure what you are saying here.
Sorry, what I wanted to say is that your module is so cheap than it's discouraging to do ours.
@Grumpy_Mike No matter how long the LEDs run, they flicker and are at around 60% of their maximum power.
What I don't understand is that the Chinese module is working fine. Here is a photo of the module's MOSFET and the one I am using.
What I don't understand is that the Chinese module is working fine. Here is a photo of the module's MOSFET and the one I am using.
According to the data sheet that FET will not work properly.
The fact that you have a Chinese module with that FET on it and it works in a different way to the data sheet suggests to me that it is using a fake IRF520. You never know what is inside these fake chips and it might just be that there is some logic level designed silicon they put into many devices. I doubt it will be the same specification as a real IRF520.
It is just that you have a faulty design and the fake IRF520 is compensating. You might consider this to be lucky but as you can see with your attempts to recreate this module without understanding it maybe you are unlucky.
Ok thank you for these explanations. I will look for a compatible MOSFET. I will ask you for confirmation
So I found a MOSFET that's rated for logic input (RFP50N06 Datasheet → These transistors can be operated directly from integrated circuits) :
I also found this, but I'm not sure if it's logic input compatible (cheaper) :
