Whistle from motherboard when programming through LPT!

Case of my PC is open and I hear weak whistles when programming EEPROMs using LPT. The application is mine, driver is not. What can produce the sound?

Reply to
Valentin Tihomirov
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The little filter caps on the LPT port might be slightly piezoelectric ? :)

-A

Reply to
Andre

This can be caused by two simple phenomena. The first is power supply droop. I have had this happen on electronic devices before and it was cured by slightly larger filter capacitors. The second is that some devices undergo constriction effects in rapidly changing electrical or magnetic fields. The whine from a television or monitor is due to magnetostrictive effect in the transformer, and some ceramic capacitors are also known to do this, due to voltage induced dimension changes. In other words, something similar to piezoelectric effects.

Cheers!

Chip Shults My robotics, space and CGI web page -

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Reply to
Sir Charles W. Shults III

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