Expanded polystyren as a muffler

Thread Starter


Joined Jan 6, 2004
I was asked to help in finding a simple/cheap way to muffle the whine coming from four small (really small) inverters driving electroluminiscent panels used in PC "moding".

Snooping with a scope found that output frequency goes from 400 to 2000 Hz depending the units.

Since they are commercial (sealed) units the only mean that came to my mind was to pack them in expanded polystyrene (the one used for protective packaging).

My capability to hear high pitches was lost years ago so I can not judge by myself and have to relay on what younger people says.

The power involved is minimal. Temperature of the inverters doesn't change when in use.

My questions:

a) is this a valid means whitout using a bulky packaging of polystyrene? There is little space available.

b)may I be sure that I am not creating another unexpected problem? Not being hygroscopic, my last concern is electrical isolation or ...?

Suggestions will be appreciated.


Joined Jan 28, 2005
One thing to keep in mind is that polystyrene is a thermal insulator. If your module produces any heat the module will be subjected to potentially damaging temperatures. This could degrade the reliability of the module.

You should do some temperature testing of the insulated module at the intended maximum ambient operating temperature to make sure that the module will withstand the elevated temperature.

Good Luck,