On Wed, 3 Dec 1997, I wrote:

> I'm getting a range of 10 feet using a single comparator from an LM339.
> The output of the LM339 is digital.  I'm not good at analog, so I
> converted to digital as simply as I could.

> I'll post the schematic and more notes at http://www.hamjudo.com/sonar

The schematic of the input circuit is on the web page now.  My apologies
to the 14 people who it the webpage before there was anything usefull.
Hit reload if you were one of the early ones.

I made the schematic with xpaint on my Linux box.  Are there any real
packages for doing schematics that will run on Linux?  How about under
DOSEMU and/or WINE?  My email address is paulh@hamjudo.com, no need to
involve the whole list on Linux trivia.  I'll put the answers on my
website, unless requested not to.

Note: I get the digest, so I won't see any posts to the list until
tomorrow morning.

--
paulh@hamjudo.com  http://www.hamjudo.com
The April 97 WebSight magazine describes me as "(presumably) normal".