Re: Accelerometers for >1000g measurements

On 05/09/2024 15:07, john larkin wrote:

On Thu, 05 Sep 2024 06:22:04 GMT, Jan Panteltje <alien@comet.invalid>
wrote:
 

On a sunny day (Wed, 04 Sep 2024 19:57:04 -0700) it happened john larkin
<jlarkin_highland_tech> wrote in <md7idj1plqodnthuqpcemaphbrtotlqveh@4ax.com>:
>

On Wed, 4 Sep 2024 18:30:46 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:
>

So for this customer gig I need to measure the actual acceleration of a
parallel-rod transmission line that's being pounded into the ground with
a built-in slide hammer.  (It's for measuring soil moisture and salinity
by TDR.)
>
We're thinking about putting the TDR pulser and sampler in the part that
gets pounded (in a potted module obviously), so knowing how bad the
acceleration gets is going to be important.  I expect that it'll be
several hundred g in volcanic soil, so a full-scale range of 1000-2000 g
would be about right.
>
None of the MEMS IC accelerometers go anywhere near that high.
Measurement Specialties makes them, but they're $160 in onesies, e.g.

>
>
If you can make it emit some ultrasonic sound you can measure the received frequency shift from far away?
Same for RF likely...
?

 No, just measure the voltage or the charge that it generates under
acceleration. It's a polarized, piezoelectric ceramic thing for 30
cents.
 https://www.mouser.com/c/?q=ceramic%20resonator
 One might also measure its resonant frequency vs acceleration.
 I wonder how one would test it. At 2000 g's.
 Even ceramic caps are notoriously microphonic. Maybe just look at your
own power supply rail.
 The guys who make expensive crystal oscillators go to great lengths to
make them G-insensitive. I suspect that the folks who make cheap
oscillators don't.
 You could lay out a strain gauge on the PCB too.
 During WWII, we fired proximity fuze shells out of rifled cannons at
20,000 Gs and 20,000 RPM. With tubes.
 

They were very special small tubes and the whole circuit was encapsulated in wax.
John