Oscope & Piezo Electric to capture Airgun Barrel Vibration ?

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jayTechStuff

Joined May 29, 2022
7
You'll want an analog output from the accelerometer for sure ( as opposed to digital like I2C to be read by a microcontroller). I would look for the greatest acceleration (g) range possible, as I expect the g level could be fairly high.

An o'scope will give you a time waveform – I'm not sure how much you'll learn from that. An FFT ( which better scopes can do) will shown you the frequencies that make up that waveform.... which may also not tell you much. It would tell you the harmonic frequencies of the barrel, but I suspect this won't tell you much. The natural frequencies (i.e., harmonics) of the barrel are controlled by the geometry and materials of the barrel, but there may be slight shifts in frequency related to pressure in the barrel.

Keep in mind that something long in one domain is sharp in the other. For example, a sine wave continues forever (is broad) in the time domain, but sharp – a single peak –:in the frequency domain. We use this fact to excite natural frequencies of an object. A bump or impact generates broad band vibration that will excite the natural frequencies of the object. An extreme example of this is an anchor drop test on a ship. The anchor and chain are paid out quickly as possible, then snubbed before it reaches the bottom. The resulting impulse will excite the natural frequencies of the hull.

The impulse when the gun is fired will do the same to the barrel, but you'll need to see the frequency domain to make sense of it.
Irving, where did you find those chips at ? I been looking at amazon but probably much better places that are very specific to these needs ?
 

Irving

Joined Jan 30, 2016
3,845
Irving, where did you find those chips at ? I been looking at amazon but probably much better places that are very specific to these needs ?

analog.com, but the raw chips aren't much use to you, you need properly laid out PCBs. The low end chips are the ones you'll find for hobby use and therefore useable boards because they are cheap... the higher spec stuff needs more specialist purposes and attract a high premium hence you generally won't find an off-the-shelf solution.
 
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strantor

Joined Oct 3, 2010
6,782
Here is ADXL1005 on eval board for $44.80.
ADXL1005 has 14X bandwidth of ADXL335 (without caps)
ADXL1005 has 460X bandwidth of ADXL335 (with caps installed as delivered on board)
ADXL1005 eval board cost 2.75X of ADXL335 board on Amazon but only measures in 1 axis while ADXL335 measures in 3 axes.

If you want, you can get 3X ADXL1005 board for $135 to have a super fast equivalent of ADXL335, but I echo @Irving 's suggestion to go with ADXL335 first, probably remove the installed capacitors, and see if that leaves you wanting more.
 

Irving

Joined Jan 30, 2016
3,845
Here is ADXL1005 on eval board for $44.80.
ADXL1005 has 14X bandwidth of ADXL335 (without caps)
ADXL1005 has 460X bandwidth of ADXL335 (with caps installed as delivered on board)
ADXL1005 eval board cost 2.75X of ADXL335 board on Amazon but only measures in 1 axis while ADXL335 measures in 3 axes.

If you want, you can get 3X ADXL1005 board for $135 to have a super fast equivalent of ADXL335, but I echo @Irving 's suggestion to go with ADXL335 first, probably remove the installed capacitors, and see if that leaves you wanting more.
Thats a good deal on the ADXL1005, 30% off the 1000up price of the raw chip...
 

strantor

Joined Oct 3, 2010
6,782
Thats a good deal on the ADXL1005, 30% off the 1000up price of the raw chip...
Yes it is. I just ordered 3 myself, as I have a project on the back burner very similar to @jayTechStuff 's project and I want to compare ADXL335 to ADXL1005.

I tried to order 4 but Mouser poo-poo'd my request. Apparently these are endangered species just like rifle primers and Raspberry Pis.

EDIT:
Just ordered a 4th ADXL1005 board from Digikey along with an ADXL373 board with SPI and I2C interface to compare the performance of the analog Vs. serial output sensors.
 
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