wrote in message
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On Friday, April 7, 2017 at 4:01:09 PM UTC-4, Jim Wilkins wrote:
wrote in message
...
On Friday, April 7, 2017 at 3:13:24 PM UTC-4, Jon Elson wrote:
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:
There definitely are electronic stethoscopes on the market. You
can
buy
them at auto parts stores. They have some sort of vibration mike
on
the end
of a long rod, so you can poke the rod down into the works where
engine
accessory bearings are.

Jon

Yeah, I've seen those, but I thought the active filters would make
them a lot more useful in something noisy, like an IC engine. I
made
some audio filters for use in ham radio a couple of decades ago,
and
they were great when I was playing with direct-conversion
receivers,
which let a lot of noise through.

--
Ed Huntress
KC2NZT

============
How about a "waterfall" or spectrogram display on a smart phone,
showing both frequency peaks and repeating pulses and how they
relate
to engine RPM?
http://www.epanorama.net/newepa/2013...gnal-analyzer/

Er...ah...well, yeah, I guess. Then you have to teach users how to
read the displays. g

--
Ed Huntress

Users already have to learn how to interpret the sounds. This could
show if the sound is related to the speed of the crankshaft, or of the
camshaft, alternator, etc.

The upper and lower filters could isolate individual sounds which they
both see and hear. Without the display they don't know what the
filters are doing.
-jsw