On Saturday, April 8, 2017 at 11:45:46 AM UTC-4, Tim Wescott wrote:
On Fri, 07 Apr 2017 08:51:21 -0700, edhuntress2 wrote:

Yo Jim -- and anyone else who may be interested.

I spend an hour last night tracking down some noises in my furnace
blower, using my usual piece of aquarium hose stuck in my ear g, and I
wondered if there might be a market for an advanced kind of mechanic's
stethoscope -- something that ought to be a piece of cake for someone
like you.

Maybe something like this is on the market. If so, forget it. If not,
consider this:

I had two noises, from different sources, and the interference between
them made it all but impossible to find the origins of the noises. One
was some mechanical interference between the centrifugal fan and its
housing, at one end of the armature shaft; the other was vibration
resulting from stickiness in the centrifugal throw-out switch (a
fail-safe switch that prevents the gas valve from opening), at the other
end of the shaft. I finally took the whole thing apart and found both
problems, but it wasn't easy to find them when the motor wasn't running.

So, I wondered about the idea of making a small, cheap, battery-powered
amplifier, with a mike and a headphone jack, that contained a couple of
active, adjustable audio filters, one high-pass and another low-pass.
Made a notching filter or bandpass filter to make it slick.

I don't play with engines much these days, but I can recall times when
such a device would have made quick work of tracking down engine noises.

There it is. If you make it and sell it, the idea is yours. Watch out
for patents.

I'm crappy at product marketing, sales, and financing, but good at
"techie" stuff like making this gizmo for cheap in an attractive housing.

So if you want to do the half that's hard for me, give me a call and I'll
do the easy part.

Should be able to do the signal processing digitally, so the hard part
will be making a user interface that allows the pro users to get the most
out of it while making it easy enough for the ordinary guy so it doesn't
just get thrown through the wall.

--
Tim Wescott
Control systems, embedded software and circuit design
I'm looking for work! See my website if you're interested
http://www.wescottdesign.com

That's a tempting thought, but look at it from a marketing perspective: This is a low-tech, analog device, and as Jim and Clare showed, there are slick, digital solutions on the market that even turn a cell phone into an audio spectrum analyzer.

I happen to like these simpler solutions, but I don't think a lot of people would go for it. The market would be really small. So I don't think it's viable except as a hobby thing that one might do for his own use and satisfaction.

I think we should pass on this one.

--
Ed Huntress