Plastic Beach - Water Wave Machine

[hydrophyte]

I got the FOC driver in the mail and soldered the pins in place. I hope I can get this to work with a brushless motor for the ripple tank concept.



As mentioned previously, I have my eye on the Ultum Nature System 60S aquarium. This tank has a cool broad + shallow (23.62" X 14.17" X 7.09") shape and I think it might work well with either the ripple tank or the vortex aquarium idea. I also have a concept in mind for a concrete stand and made a quick CAD sketch. This would require a very simple concrete mold with just some pieces of plywood comprising a box within a somewhat larger box and the concrete mix poured into the space between them to make this open concrete box shape.

 

[hydrophyte]

I did it! I got this cheap L298N brushless driver to work! I had a frustrating time because I really couldn't get it to run with the motor at all, but in another venue where I asked for help a respondent pointed out that the red power indicator LED (visible in photo) was out. So the first board I tried was just a dud. I ordered a second one and it works fine. There are better brushless drivers, but this one is good enough for experimentation. Just guesstimating it looks like the max speed I can get with this mini gimbal motor is about 300rpm.

I think I'll re-prioritize the ripple tank idea again and see if I can get this to work with an updated mechanism design.

 

[hydrophyte]

Took forever and I don't know if it will work yet, but I got the ripple tank mechanism almost all assembled. It still needs the electronic signal + power connections and a second piece of aluminum extrusion attached at a right angle for positioning on the wall to suspend over the tank water...



This is intended to work in a manner similar to a telegraph sounder or doorbell mechanism, with a controllable electromagnet pulling and releasing a piece of steel to create the up-and-down paddle motion. The large white bead at the end of the arm will serve as the ripple-generating paddle. Here's a better view showing the electromagnet, thick steel collar, bearings and return spring...



Reviews for this economy electromagnet described it as "weak", "loud" and "hot". But it already has its own circuit board, so it should be easy to connect for a test. If it runs at all and if I need better performance, I'll look for an upgrade or build my own later.

I'll try to get it installed this weekend to see how it goes.

 

[hydrophyte]

Well it was rather fussy work and took quite a while to complete, but I got the ripple mechanism updated and installed with one of my shallow 24" X 24" tanks. It still needs substrate and an aquascape, but the ripple generation seems pretty good. I might add a few nano fish eventually, or just leave the setup as kinetic water sculpture with a sparse planting. The center of the square space will remain as bare sand for the best view of the water ripples....





There is 16" of space on the 80-20 aluminum extrusion above the mechanism and I intend to build an enclosure for the micro controller to position there.

I like how some the finish details turned out ...





The spring (an RC car shock) at the rear is stiff in comparison to the electromagnet pulling strength, but the elastic band provides opposing force. Both are adjustable for fine tuning...



I also uploaded a quick Instagram video clip you should be able to view if you have a login...

 

[Dogtemple]

That’s awesome, such a cool idea and nicely executed.

Are the ripples in your video that fast in person or is it sped up on Instagram? It was hard to tell. When reading through it I imagined the ripples to be more like a drop of water and the ripples would sort of fade or decay and then another new drop of water would come along and start the process again every few seconds.

 

[hydrophyte]

That’s awesome, such a cool idea and nicely executed.

Are the ripples in your video that fast in person or is it sped up on Instagram? It was hard to tell. When reading through it I imagined the ripples to be more like a drop of water and the ripples would sort of fade or decay and then another new drop of water would come along and start the process again every few seconds.

The ripple rate is controllable with Arduino. That clip shows something like 2 ripples/second, but I can edit the code to make single ripples with long pauses or a good deal faster.

 

[hydrophyte]

Really interesting reduction mechanism, the capstan drive, I recently encountered in YouTube suggestions:



With cordage/rope transferring power instead of metal gears, this option could be especially useful for wet environments. It's also practically silent and it looks cool, so it might be an idea to explore for paddle motion with an aquarium wave machine. Although you would still have to resolve the motor linkage and bearings.