> Here's the answer from another thread: > > "It's not normal, but it means they used cheap capacitors. This is known > as the acoustic noise issue. It's related to PCB vibration as a result > of the piezo electric effect on the caps. What is the timer tick > frequency? ... The 1ms gives a nice 1kHz tone. It's related to the > voltage change of C4 exit." Well, that still doesn't explain why the noise is only there when I insert thermal.o. Also, the noise seems to be higher than 1 kHz (I'd guess 5-10 kHz). Jean-Marc -- Jean-Marc Valin, M.Sc.A., ing. jr. LABORIUS (http://www.gel.usherb.ca/laborius) Université de Sherbrooke, Québec, Canada