Electrical buzzing noise from AC-DC 24V10A 240W Switch Power Supply

Hello all!

In an attempt at trying to make my own CNC machine, I've taken the first step and ordered all that I believe I need at this point. One of the items I've ordered and received was the power supply for the stepper motors. I've got it wired up and plugged in and when I adjust its output to its maximum voltage (24), everything is fine. I can go as low as 15V. I'm a little concerned though because when I get to about 20V and below, It makes an audible electrical buzzing noise. Is this normal?!? It's not real loud but definitely noticeable.



Hi, the buzzing is the supply trying to get your output down to 20V or below.
Switch mode supplies use high frequency PWM to regulate the output, if the supply is designed for 24V then that is what it is optimized for, not 20V or below.
What you are asking the supply to do when you adjust below 24V, is provide a very low duty cycle which is not optimal for the output filtering.
So please treat your SMPS with respect and leave it at 24V, the output it was designed for.
The spec for the SMPS will probably tell you what output you can safely adjust to.

Tom...... :slight_smile:

24V is rather low for a CNC machine. Most stepper drivers are good for 48V or more
and you get faster rapids from a higher supply voltage.

You can try to buy a power strip but the noise is definitely because of the coil squeal, technically its okay to hear some squealing noise when its on and near full power usage but you claim when its off its making that noise leads me to believe you have defective caps. If it does stop buzzing when you unplug the power cord from it then the fault is with the power supply.