Whistle from motherboard when programming through LPT!

[Valentin Tihomirov]

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?

 

[Andre]

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?

The little filter caps on the LPT port might be slightly piezoelectric ?

-A

 

[Sir Charles W. Shults III]

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 - http://home.cfl.rr.com/aichip