Re: Inductor arrangement for boosting low-voltage piezo drive

Robert Baer wrote:
There are piezo sounders that only need a voltage across them to make a lowd sound. Is there a reason to re-invent that wheel? 

I can't find one at a low price that will make a loud sound at 3V,
is all. The self-drive and internal-circuit type don't use any
voltage booster AFAIK, so aren't louder than my direct push-pull
drive. I don't need 80dbA, as the person is only 2' away. I don't
want to scare them witless - but there must be no mistake about what
they've heard despite noise and poor hearing. Push-pull gives 6V P-P
and is almost passable, I just figure that the boost inductors might
give me 12V P-P. Guess I'll have to try it.

Boris Mohar wrote:
> Drive an RS232 chip...

I've done that with 40KHz sonar, but I'm worried that the quiescent
current will get me. The device must last for the shelf life of the
2 AA batteries, as it's sealed and will likely be replaced when the
batteries fail. I was actually going to go with a CR2430 or similar
lithium battery, before it was pointed out that it needs an LED to
back up the beeper. What's the lowest quiescent current you can get
in a 3V RS232 driver chip?

Rich Grise wrote:
I vote for a Sonalert. :-) 

The only Sonalert that will produce 80db at 3V (the SC307N) is $19,
more than my entire BOM cost :-).

Roger Lascelles wrote:
> If it is a bare brass plate...

It's a little ABS resonator case with the brass plate inside.

Clifford Heath.
.