Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

How to stop PWM noise?

Status
Not open for further replies.

tompson

Newbie level 5
Newbie level 5
Joined
Mar 20, 2006
Messages
9
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,380
pwm noise

Hey there guys,

So I have a new water cooled computer with three very big 12" fans. I want these to be temperature controlled, so I figgured the best way was off the motherboard fan header (since this can be set of the CPU temp).

The problem is that the output off the motherboard is PWM (pulse width modulated) and these big slow RPM (but very high air flow) fans make a huge amount of PWM noise at slow fan speeds. You can hear the 60Hz switching noise, which makes the fans louder at slow speeds then they otherwise are at medium speeds.

Does anyone know a really nice trick to take PWM signals and turn them back into analog voltage modulated signals.... Besides just using an active low pass filter?

Thanks, much appreciated,
Jonno
 

Hi, Put a large inductor in series with your FAN +Line. and a diode needs to be placed from the +line to ground before the inductor. Like a step-down SMPS.

regards,

Paul.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top