I created a mobile phone controlled home automation system that includes input modules, relay switches, and dimmers.
I used an Arduino nano connected to one of those cheap IRF520N modules from aliexpress (fig.1) to control a 12V mini led amplifier (fig.2) that dims a 12V led strip which worked perfectly.
When I've finished the breadboard prototype and created my own pcbs so i can install it in my house and panel board I decided to use IRL540N with 150ohm resistor between the gate and the Arduino pin and 10Kohm between the gate and the source. (fig3&4) (Please neglect the 4AA batteries the photo is from the web , the source is 12VDC) .
The dimmer works perfectly the only problem is using this setup I hear an audible noise when the PWM is different from 255 and 0.
I didn't have this problem before with the IRF520N module, can you please help me.
It is a minor point, but the 10k resistor should not be between gate and source. Its only purpose is to define the Arduino output during initialisation, so it should be between the Arduino pin and ground. The "fault" it corrects belongs to the Arduino, not the FET.
It is rather peculiar to suggest you were using the IRF520 module to control in turn a "LED amplifier" module which contains the FET with the necessary drive capability. Never mind, you have apparently bypassed that. (I must get some of those "LED amplifier"s to play with. )
You will just have to live with the noise or figure out which part to soundproof, You are using audio PWM to control significant currents, electromagnetic effects in inductors or even loose wiring will translate this into vibration.
Hello and thank you for your replies ...
After further investigations I noticed that the sound is coming from the power supply itself, could it be that some component got loose in the power supply?
No, it is simply that the power supply is seeing the PWM current switching on and off, causing slight movement due to the magnetic fields in some component. The component does not need to be loose as such, it will simply bend ever so slightly.
Put a capacitor - 1 mF - across the power connections to your FET module. The capacitor will see the fluctuating current more than your power supply.
Hello Paul
Thank you for your reply.
Sorry for the delay, please note that I tried to drive those amplifier modules from Arduino with no luck, thus the voltage range 5-24V that's why I used the IRL540N.
As for the noise, I reduced the frequency to 125hz its sounds much better now, and I will try to glue the capacitors and the coils in the power supply to the PCB.
Could you please specify where the connect the capacitor to the fet ? between the VCC and ground of the power supply?
Please note also that I noticed something weird when I close or open my rolling shutters the led strip flashes when the motor starts operating or stopping.
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