In message , PHXSYS writes >Hi! > >I want to listen to a fluid when it begins to boil. I am looking at using a >small mic like the panasonic WM-62A and a frequency to voltage to converter >like a LM2917N-14 and an A/D converter. What do you think, am I on the right >track. Has anyone done something similar to this and would be willing to offer >comment? I don't think your approach will work; the sound emitted when the liquid begins to boil will be something like white noise, not a single frequency. How about amplifying and rectifying the mic. output, and using a comparator. Leon -- Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.