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From: John R Walliker <jrwalliker@gmail.com>
Newsgroups: sci.electronics.design
Subject: Re: Accelerometers for >1000g measurements
Date: Thu, 5 Sep 2024 11:02:41 +0100
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On 05/09/2024 07:22, Jan Panteltje 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...

Attach an adhesive label printed with a black and white wedge to
the rod.  Illuminate with uniform light and view with a photodiode
lens slit combination.  Capture the velocity waveform on 'scope.
Calibrate at low speed.
I expect the acceleration peak might only last a few microseconds
but could be many thousands of g.

John