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