"RST Engineering" wrote in message
...
Understood. What I started out to do (and still plan on doing) is to have
a device that will stay permanently mounted to the engine that can be
calibrated (adjusted, signed, pick a verb) when the engine is known to be
good and light a "your engine is about to come apart" lamp at the
appropriate time.

What this group seems to be leaning toward is a lab quality device that
will allow for sophisticated diagnostics. That ain't the thrust of my
Kitplanes columns. KISS and BURP.

Jim


As is tradition, we tend to get off topic ;-)
I think you can accomplish this using the methods discussed.
Mount 2 proximity probes 90 degrees apart.
Calibrate the readings for normal low vibrations (be sure to account for any
nonlinearities in the probe).
Design the circuit to trip the buzzer/lamp when the vibration exceeds the
normal level.
You may need some analog circuitry to help (gain, etc).
But you don't need to get much fancier than that.

Adam