-
We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.
Is it possible for high-frequency circuits to make audible noise?
- Thread starter CTho9305
- Start date
zephyrprime
Diamond Member
Yeah sure. But it wouldn't be the high freq that does it. It'd be the low frequencies. The freqs within human hearing. An inductor coil can produce a magnetic field that causes a nearby metal sheet or something like that to vibrate. This is what causes some fluorescent lights to hum.
Hayabusa Rider
Admin Emeritus & Elite Member
I had a bad cap on a power supply do that.
davesaudio
Senior member
two frequencies that are very close can beat against each other and produce a third new low frequency
ethebubbeth
Golden Member
heh, my cable modem and wired router both make extremely annoying high pitched whines =/
Yes and no. They can make frequencies audible to human hearing (Low-mid), and no, it's not generally harmfull, and mostly a nuisance. The PCMs on my two cars do it, and have done so for nine years with no incidents. I also had caps in my home power amplifiers do it at power-down, and drove me nuts.
PowerMacG5
Diamond Member
My former one did that too. I'm sensitive to noise, so it bothered me until the batteries were literally dead and the mouse not functioning anymore. I returned it and got a replacement. It seemed they fixed the problem in the newer ones because when I replaced it a few months ago it never made the noise again. I have now moved onto the Bluetooth desktop and it never makes a noise (I can still hear it though when I put my head near the mouse).
Well, the gradient coils do move (albeit very slightly) because of the enormous forces generated by the interaction of the static and dynamic fields - it's difficult to hold the wires still, as there could potentially be several hundred lbs of force. It's this movement that generates the noise. Simply altering the magnetic field doesn't produce the noise - it's the forces on the wires.
The same thing explains the noise that switching power supplies make - the ripple current in the magnetic components constantly varies, resulting in oscillating magnetic forces in the inductors, which can cause loosly wound coils to vibrate. In the case of PC VRMs, an audible vibration is likely to come from a subharmonic oscillation (maybe mechanical) as the operating frequency is typically in the MHz range.
The same thing explains the noise that switching power supplies make - the ripple current in the magnetic components constantly varies, resulting in oscillating magnetic forces in the inductors, which can cause loosly wound coils to vibrate. In the case of PC VRMs, an audible vibration is likely to come from a subharmonic oscillation (maybe mechanical) as the operating frequency is typically in the MHz range.