Hi there, I have a problem obtaining more than 130dB at 1m, with a PZT device at high frequency ( same as used in ultrasonic dog chaser, 20...25Khz ). Usual these PZT devices have 10 to 50 nF and maximum peak voltage less than 70V. Do you know a good design for the acoustical resonator and/or high eficiency PZT driver ? Thanks, Vasile -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu