Something completely different.

6 Attachment(s)

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

Thanks tonyfoale! We've added your Linear Velocity Transducer to our Motorcycle category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-linear-velocity-transducer"> <img src="https://www.homemadetools.net/uploads/247767/homemade-linear-velocity-transducer.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-linear-velocity-transducer">Linear Velocity Transducer</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/dyno'>dyno</a>, <a href='https://www.homemadetools.net/tag/measurement'>measurement</a> </div> </div> </div> </div>

Quote:

Originally Posted by DIYer

Thanks tonyfoale! We've added your Linear Vertical Transducer

Linear VELOCITY Transducer.

Thanks, all fixed.

Very interesting Tony!

The only thing I can wonder about is your using an aluminium tube to house your magnets. Did you want to use only the ends of the magnets? Because aluminium and magnetic flux repel one another. The ends of your composite magnet will see the greatest flux concentration. It may be the method behind your madness. Because you have done quite a lot of research in the rest of this design.

Among other things I design loudspeakers for a living. Working as a consultant for a number of different companies. I do a lot of design work with various types of magnets for designing woofers, and tweeters of various sizes and shapes.

Quote:

Originally Posted by mwmkravchenko

Very interesting Tony!

The only thing I can wonder about is your using an aluminium tube to house your magnets. Did you want to use only the ends of the magnets? Because aluminium and magnetic flux repel one another. The ends of your composite magnet will see the greatest flux concentration. It may be the method behind your madness. Because you have done quite a lot of research in the rest of this design.

Aluminium is paramagnetic and relative movement of aluminium and a magnetic field will generate a repulsive force as you say but in this case there is no RELATIVE movement. The magnet and aluminium tube move together, I pointed this out in the video when talking about eddy currents.
Yes the ends of the magnet see the greatest flux concentration, that is what is required and I demonstrated that with my little screw driver test. If there were areas of concentration along its length a lack of linearity would ensue in the output signal, it would be position and velocity sensitive. I only want velocity sensitive.
There is no method in my madness, it just comes naturally.

Quote:

Originally Posted by tonyfoale

Aluminium is paramagnetic and relative movement of aluminium and a magnetic field will generate a repulsive force as you say but in this case there is no RELATIVE movement. The magnet and aluminium tube move together, I pointed this out in the video when talking about eddy currents.
Yes the ends of the magnet see the greatest flux concentration, that is what is required and I demonstrated that with my little screw driver test. If there were areas of concentration along its length a lack of linearity would ensue in the output signal, it would be position and velocity sensitive. I only want velocity sensitive.
There is no method in my madness, it just comes naturally.

This very same method of using a paramagnetic metal be it aluminium or better yet copper is used in a proper loudspeaker motor to control inductance rise in a voice coil. You know this I am sure. The voice coil is an analog to your single layer solenoid winding.

You could not have done a better job of an easy to make composite magnet with very focused end high flux density if you tried.

What I failed to type the first time is I am impressed with your engineering research and competency. A pleasure to watch your videos and learn from them.

Quote:

Originally Posted by mwmkravchenko

What I failed to type the first time is I am impressed with your engineering research and competency. A pleasure to watch your videos and learn from them.

I appreciate your kind words but they make me feel like a fraud. I do very research on anything.

Here is the link to the second part of the video, I hope that you like it as much.

https://youtu.be/NCvKRgbF1uA

Quote:

Originally Posted by tonyfoale

I appreciate your kind words but they make me feel like a fraud. I do very research on anything.

Here is the link to the second part of the video, I hope that you like it as much.

https://youtu.be/NCvKRgbF1uA

Watched. And the little research at present comes from a lot of research in the past. I'm not as old as you are Tony. But I don't have to look up everything that I put my hands to either. Some things we don't loose with time. Other areas of interest require a refreshing of what we once knew well.

Congratulations tonyfoale - your Linear Velocity Transducer is the Homemade Tool of the Week!

This unique build, which further develops your previous winning Shock Absorber Dynamometer, will be useful to people doing CNC machine building.

Some more nice builds from this week:

Mill Scale Removal Methods by Haslip Cycle Works
Mill Angle Plate by bouboulas
Welding Table by fox craft
Metalworking Table by Tuomas
Vise by orioncons36
Lathe Chuck Spacers by editor@glue-it.com
Disc Punch by editor@glue-it.com
Quorn Tool and Cutter Grinder Spindle Housing by ttmrj
Circle Cutting Jig by Workshopshed
Glass Cutter by Mr.DK DIY
Clothespins by Philip Davies
Knee Mill Head Lifter by LMMasterMariner
Drill Press Sanding Drum by HandmadeCreativeChannel
Downdraft Sanding Table by Didpoolhall
Floating Tap Holder by machining 4 all
Double Duty GPIO Pins by rgsparber
Rip Cut Jig by Didpoolhall

tonyfoale - we've added your tool entry to our All Homemade Tool of the Week winners post. And, you'll be receiving a $25 online gift card, in your choice of Amazon, PayPal, or bitcoin. Please PM me your current email address and gift card choice and I'll get it sent over right away.

This is your 13th Homemade Tool of the Week win! Here are all of your winning tools:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/home-made-horizontal-milling-machine-55333#post81620"> <img src="/uploads/162905/homemade-horizontal-milling-machine-2.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/home-made-horizontal-milling-machine-55333#post81620">Horizontal Milling Machine</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/mill'>mill</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/grinding-machine-drum-brakes-55587#post82147"> <img src="/uploads/162657/homemade-drum-brake-grinder.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/grinding-machine-drum-brakes-55587#post82147">Drum Brake Grinder</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/grinder'>grinder</a>, <a href='https://www.homemadetools.net/tag/brake-drums'>brake drums</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/shock-dyno-shock-absorber-dynamometer-56478#post83755"> <img src="/uploads/163993/homemade-shock-absorber-dynamometer.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/shock-dyno-shock-absorber-dynamometer-56478#post83755">Shock Absorber Dynamometer</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/suspension'>suspension</a>, <a href='https://www.homemadetools.net/tag/measurement'>measurement</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/valve-holding-measuring-collet-58294#post87183"> <img src="/uploads/166061/homemade-valve-holding-collet.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/valve-holding-measuring-collet-58294#post87183">Valve Holding Collet</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/valve'>valve</a>, <a href='https://www.homemadetools.net/tag/holder'>holder</a>, <a href='https://www.homemadetools.net/tag/collet'>collet</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-laser-aligner"> <img src="/uploads/168729/homemade-laser-aligner.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-laser-aligner">Laser Aligner</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/alignment'>alignment</a>, <a href='https://www.homemadetools.net/tag/laser'>laser</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/double-edged-fly-cutter-63995#post100445"> <img src="/uploads/205514/homemade-double-edge-fly-cutter.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/double-edged-fly-cutter-63995#post100445">Double Edge Fly Cutter</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/flange'>flange</a>, <a href='https://www.homemadetools.net/tag/fly-cutter'>fly cutter</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/homemade-vertical-bandsaw-66678#post108045"> <img src="/uploads/211089/homemade-vertical-bandsaw-5.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/homemade-vertical-bandsaw-66678#post108045">Vertical Bandsaw</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/bandsaw'>bandsaw</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/diy-surface-grinder-67127#post109600"> <img src="/uploads/212251/homemade-surface-grinder-11.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/diy-surface-grinder-67127#post109600">Surface Grinder</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/grinder'>grinder</a>, <a href='https://www.homemadetools.net/tag/surface'>surface</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/radius-gauge-reverse-engineering-70673#post123621"> <img src="/uploads/219843/homemade-radius-gauge-3.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/radius-gauge-reverse-engineering-70673#post123621">Radius Gauge</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/gauge'>gauge</a>, <a href='https://www.homemadetools.net/tag/radius'>radius</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/making-motorcycle-chassis-what-tools-75470#post142830"> <img src="/uploads/226725/homemade-motorcycle-frame-fabrication.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/making-motorcycle-chassis-what-tools-75470#post142830">Motorcycle Frame Fabrication</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/motorcycle'>motorcycle</a>, <a href='https://www.homemadetools.net/tag/frame'>frame</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/treadmill-motors-my-modifications-83472#post173733"> <img src="/uploads/242690/homemade-treadmill-motor-modifications.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/treadmill-motors-my-modifications-83472#post173733">Treadmill Motor Modifications</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/safety'>safety</a>, <a href='https://www.homemadetools.net/tag/modification'>modification</a>, <a href='https://www.homemadetools.net/tag/motor'>motor</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/lathe-cross-slide-conversion-ball-screw-83598#post174256"> <img src="/uploads/243474/homemade-cross-slide-screw-conversion.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/lathe-cross-slide-conversion-ball-screw-83598#post174256">Cross Slide Screw Conversion</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/lathe'>lathe</a>, <a href='https://www.homemadetools.net/tag/modification'>modification</a> </div> </div> </div> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/forum/something-completely-different-83989#post175969"> <img src="https://www.homemadetools.net/uploads/247767/homemade-linear-velocity-transducer.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/forum/something-completely-different-83989#post175969">Linear Velocity Transducer</a> <span> by <a href="https://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/dyno'>dyno</a>, <a href='https://www.homemadetools.net/tag/measurement'>measurement</a> </div> </div> </div> </div>

Oops, I just noticed that I made a mistake. In the initial post I mentioned DAC - Digital to Analog Conversion. That is WRONG. It should be ADC - Analog to Digital Conversion. I made the same stupid mistake in the 2nd video maybe the 1st but I have not checked.

I certainly did not expect "Tool of the week" with this. I thought that it was too far out of the main stream for that. Many thanks, it is very encouraging.

Here is a link to the original shock dyno post https://www.homemadetools.net/forum/...6478#post83755