Thank you! I may make another revision sooner or later that brings the walls touching the LF antenna and the one next to the words “Field Extender” on your board just a wee bit higher, maybe by a mm or two. Just enough to provide ‘growing room’ for thicker styles of double sided tape.
Edit:
Just made a printables account. Published under GPL v2.0
Those are gorgeous!
I’m building an ultrasonic levitation device and need some help. My transducers don’t have their polarity marked on their pins. I’ve tried a number of different tests with my multimeter and different test circuits, and I weirdly get audio chirps regardless of which lead I designate as ground/v. Is my only real option to buy an oscilloscope? The 40khz output isn’t exactly audible to humans and my cats refuse to partner with me as test subjects.
Are they polarized? Does it matter?
Theoretically they should be polarized. I have to sequence them together (all gnd top layer/all 5v top layer —> out1/out2 on my motor driver, repeat for out3/4 on bottom layer). I may just do some trial and error. Found a small oscilloscope - I needed one anyway. That should help.
Yeap, otherwise some of the transducers will be out of phase by 180 degrees. And the idea here is controlling the constructive and destructive interference between them to control standing waves so having the math match reality is rather important.
Yeah they all have to pinpoint to create a standing wave which allows objects to float inside that pattern
Use a AA battery
Connect the leads to either end. One way will push the coil in. The other out.
Identify positive and negative this way.
Edit: looking at your picture it looks like they are identified. I’ve leg is longer and colored than the other. So I would make a standard. Long leg equals negative. Wire it with that mentality and you should be fine
IIRC, those are piezoelectric. However, I can’t recall if movement is visible when applying a DC voltage.
I colored those myself haha. Both legs are also completely equal. However, one leg DOES have a little black gasket on each one. Reviews on the transducers say, sadly, that this marking can’t be trusted. I have an oscilloscope coming tomorrow and I’ll try the battery test, too. Oddly enough, when I connect either leg in either order to my driver, I get a brief crackling sound. I’m assuming it’s just electronic “noise”, though. We’ll see!
Thank you!
These are: TCT40-16R/T 16mm Split Ultrasonic Sensor Ultrasonic Transceiver
Reviews also say 1. Don’t trust the markings to designate polarity and 2. Both the transmitter and receiver appear to function as transmitters…
ah yeah good point… so basically polarity doesn’t matter in terms of operational function of individual units, but as a group of synchronized transducers they all need to be connected in the same polarization… makes sense.
Houston we have liftoff!
Thank goodness for oscilloscopes. However, I realized these don’t appear to have a predetermined polarity. Basically, whichever sequence of transmitters I determined were positive vs negative (all wired together) seemed to work just fine!
wow yay!
what is being suspended? is that a plastic pellet like an airsoft pellet or is it heavier like a metal bb?
That’s a 3mm foam ball! Incredibly small. I’m going to test to see just how heavy/large of an object I can suspend.
Saw this today and I’m definitely going to make it after he posts an AliExpress BOM. If he takes to long I will just make the AliExpress list myself.
That might be THE thing to make the cylindrical PM3 antenna …
I decided to create an Etsy store because I needed to make a couple of shirts.
https://loveprideandcats.etsy.com/
Feel free to check me out 
This makes so much sense. Big (good) companies can’t properly pull profit from parts sales… it’s mostly a cost center… so doing this pushes off the cost to the customer and yet they seem super awesome for doing it.
I’ve worked for a few big companies and each has to make the choice to make their support and repair department a profit center or a cost center. Good companies make it a cost center and provide parts… bad ones make it a profit center… but most companies are in the middle ground of just not supplying repair parts what so ever.
