On Wed, 10 Oct 2007 18:05:36 GMT, Winston
wrote:



Here's your tweeter, a buck cheaper, for multiple units around those
larger woodpiles:
http://docs.bgmicro.com/pdf/page22.pdf (Middle of page near the bottom.)
Is that really 96 db for only two watts? Shazam!



I didn't see a bandpass diagram for that tweeter but I wonder what the
upper frequency limit is. I would like to accomodate smaller critters.
(Ants come to mind for some reason).

They vary. Some of the silver ones shaped like that from Radio Shack
would go up to 40 KHz. They had a spectrum plot printed on the box.
About any of them will do 27 KHz or so.

Some technical specs he

http://www.adelcom.net/MOTOROLA_ksn1005b.htm

Using watts is misleading because these piezo devices look
electrically like an 0.13 uF capacitor. The electrical load that they
present varies with frequency. The 50W rating they refer to is
probably referred to 8 ohms, or 20 VRMS. I drove mine at about that
level. At 30 KHz the Z is about j40 ohms, which would be about 0.5 amp
RMS, which does indeed compute to 2 watts. They ran slightly warm. I
reckon they were putting out considerably more than 96 dB. The 96 dB
@ 1 meter is measured with 2.83 volts RMS applied.

Note that the rectangular KSN1016A goes to 40 KHz.