Joe, I think what you looking for is called a "Peak-Hold Amplifier" circuit. Google on that for some examples. They are pretty easy to make with an op-amp and a few discrete parts. It will automatically acquire the peak, which you can digitize at your leisure and reset after the A/D is done. As a niggle...The piezo element will most likely be detecting acceleration, rather than velocity. Edward Gisske, P.E. Gisske Engineering 608-523-1900 gisske@offex.com ----- Original Message ----- From: "Joe Jansen/TECH/HQ/KEMET/US" To: Sent: Tuesday, March 30, 2004 10:27 AM Subject: [EE]: Analog peak capture > Hey everyone! > > I have been unsuccessful googling, and was hoping someone here would > either have an answer, a web link, or even recommended reading for me. I > am trying to build an electronic drum set similar to the overpriced models > I see at the music store. My thought is to use a piezo element embedded > in a rubber pad, through an op-amp, and feed the signal to an A/D > converter to do the velocity detection. This would then go to a PIC, > which would convert the velocity info into a MIDI signal and feed it to > the keyboard for wave generation and playback. Not too terribly fancy, > but should be functional. > > My question is: How do I insure that I am running my A/D conversion on > the highest point of the piezo elements output? the spike that is > generated will be proportional to the strength of the impact, but I want > to make sure that I run my conversion on the highest point of the output. > Is there a way to capture the peak output and then run the A/D conversion > on that? Any other suggestions? I definitely want the velocity info to > control the volume of the playback, or the whole thing becomes a gimmick. > > Thanks for any suggestions!!!!! > > --Joe Jansen > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body