6 Attachment(s)
Something completely different.
How I made an LVT for my shock dyno.
That is a Linear Velocity Transducer. As motion is involved I have made a movie.
An LVT measures linear velocity over a limited range depending on the construction details. I wanted a transducer that had a range of 100 mm. with a maximum velocity of 1 m/s.
Attachment 38588 Click for full size
Here are the ingredients. It could not get much simpler.
Attachment 38589
In the making.
Attachment 38590 Attachment 38591
What is inside and mounted.
Until I made this device I got the velocity information in the usual way of measuring displacement with a potentiometer and differentiating that signal. The process of numerical differentiation leads to noise in the velocity signal. The noise level depends on the resolution of the DAC (Digital Analog Conversion). I used a 12 bit LabJack U3 to convert the data, if I had used a 10 bit Arduino the noise level would have been 4 times more.
This pic shows the difference between getting the velocity direct from the LVT and indirectly from the potentiometer.
Attachment 38592
I still want displacement information, but I now get that by integrating the velocity signal which reduces noise. I get a slightly better displacement signal from the velocity than directly. This is often termed a "win-win".
Attachment 38593
The movie is in two parts, the first shows the making and the results. As of writing this the second part is not ready but will describe the simple electronic bits and discuss resolution and range considerations. I'll add the link when ready.
https://youtu.be/s0aUpGoeBIA