Hi!

The Original Piezo diaphragm was a standard 2" in a 3"
Element,........

I tried a standard 4/28 (12Vdc) Piezo Horn alarm/siren at a store
(Ralph's...) to test, and I got about what would sound like 2--3 volts
going through it,...... not loud, hardly audible for an alarm.

I tried a 4/28 (12Vdc) Metal Buzzer Alarm at home with 40ohm
resistance, and the Alarm Board emitted 40VAConly, and the Alarm was not
audible. The VOMs are a factor in the alarm. The more ohms the more VAC
output.

Do you think 12volt transducer using VOMs at a "4 volt VDC
capacity" would sound loud since it would drop from Ultrasonic 40Khz to
Sonic 5Khz...?

Thanx

Bob