ANOTHER tornado machine :D

[Things]

From basically a couple days before I started this thread, and I'm still going on it

Mostly waiting on stuff from China. I ordered some more ultrasonic foggers which seem to have gone missing in the post, so they've had to resend them, so it's gonna be sitting around waiting for another couple of weeks. Also had to order a higher current 12V SMPS as the computer power supply I was using has a problem with the protection circuitry and keeps cutting out

 

[Things]

So the electronics for this project has ended up being much more of a nightmare than I anticipated

Those familiar with the Arduino will be aware that it's stock PWM frequencies are 490Hz and 970Hz. Running the fans off PWM directly turned out to be extremely noisy, basically to the point where you'd have to raise your voice to have a conversation in the same room. The only other clock prescalers gave ~32Khz and ~62Khz PWM frequencies, which probably due to the motor's inductance, didn't do anything at all.

I decided to build up a couple of beefy RC filters to try and smooth out the PWM - they worked, but because of the resistors they did waste a bit of power, but most of all, they were extremely hard on the power supply (and the caps in the filter itself too). The only thing limiting inrush to the cap was the overall resistance of the wires/FET's etc, and the RC filter resistors. I calculated something like 50A peaks into the caps. One of the caps later decided to vent. Now the screeching noise had moved from the fans to the power supply.. which can't be good for them.

I decided to scrap the RC filters and attempt some LC filters instead. Essentially I was creating a crude PWM-based buck converter. I ripped a few random inductors out of a computer power supply, along with a few fast recovery diodes. In order to get away with a smaller inductor though, I also had to up the PWM frequency to ~32Khz, so I did this for one of the non-critical timers. Surprisingly, without any calculations or anything, it worked The fans were now quiet, and the PSU too.

However, I now had an EMI-spewing mess, which would constantly reset and crash the microcontroller - bah! I knew at this point a complete rebuild of the controller would be necessary, as the previous design was a total fail from an EMI standpoint.

I decided I'll put all the high current, high speed switching stuff and LC filters in a separate metal box, instead of trying to put it all in the same box as the Arduino.

Also after having to remove the controller from the machine countless times to work on it/program it, I decided to use pluggable screw terminals this time.

I think it came out pretty well, and best of all, it works perfectly, with very minimal heating of the inductors and kickback diode, easily taken care of by a small fan. The FET's now run totally cool

I think it came out pretty well.

The switch/LC filter box:

New controller + driver box connected for a test:

Basically now I'm just waiting on a larger SMPS to install permanently, then I can mount all the electronic and wire it up neatly.

It also turns out shining lasers through it is the most awesome looking thing ever .. it looks so much better IRL than I could get a pic of.

 

[Things]

So the electronics for this project has ended up being much more of a nightmare than I anticipated

Those familiar with the Arduino will be aware that it's stock PWM frequencies are 490Hz and 970Hz. Running the fans off PWM directly turned out to be extremely noisy, basically to the point where you'd have to raise your voice to have a conversation in the same room. The only other clock prescalers gave ~32Khz and ~62Khz PWM frequencies, which probably due to the motor's inductance, didn't do anything at all.

I decided to build up a couple of beefy RC filters to try and smooth out the PWM - they worked, but because of the resistors they did waste a bit of power, but most of all, they were extremely hard on the power supply (and the caps in the filter itself too). The only thing limiting inrush to the cap was the overall resistance of the wires/FET's etc, and the RC filter resistors. I calculated something like 50A peaks into the caps. One of the caps later decided to vent. Now the screeching noise had moved from the fans to the power supply.. which can't be good for them.

I decided to scrap the RC filters and attempt some LC filters instead. Essentially I was creating a crude PWM-based buck converter. I ripped a few random inductors out of a computer power supply, along with a few fast recovery diodes. In order to get away with a smaller inductor though, I also had to up the PWM frequency to ~32Khz, so I did this for one of the non-critical timers. Surprisingly, without any calculations or anything, it worked The fans were now quiet, and the PSU too.

However, I now had an EMI-spewing mess, which would constantly reset and crash the microcontroller - bah! I knew at this point a complete rebuild of the controller would be necessary, as the previous design was a total fail from an EMI standpoint.

I decided I'll put all the high current, high speed switching stuff and LC filters in a separate metal box, instead of trying to put it all in the same box as the Arduino.

Also after having to remove the controller from the machine countless times to work on it/program it, I decided to use pluggable screw terminals this time.

I think it came out pretty well, and best of all, it works perfectly, with very minimal heating of the inductors and kickback diode, easily taken care of by a small fan. The FET's now run totally cool

I think it came out pretty well.

The switch/LC filter box:

New controller + driver box connected for a test:

Basically now I'm just waiting on a larger SMPS to install permanently, then I can mount all the electronic and wire it up neatly.

It also turns out shining lasers through it is the most awesome looking thing ever .. it looks so much better IRL than I could get a pic of.

 

[3Pig]

:drool: That is too freaking cool! Looks like layered galaxies, I'd kill to see that in person

 

[Trevor]

Your pictures remind me of actual radar scans of tornadoes.

It's hard to see exactly where the radar slices are, but this is a 3D model I made of the 2013 Moore tornado constructed from radar sweeps.

Trevor

 

[Things]

That's epic!

The cross section looks basically identical to satellite/radar images of cyclones/hurricanes, too.

 

[Things]

:drool: That is too freaking cool! Looks like layered galaxies, I'd kill to see that in person

Let me know if you're ever in Townsville

 

[Things]

A few more pics, and a vid:

 

[MarioMaster]

The laser lines look crazy good through the vortex - it's like a flat time tunnel type effect.

From the pictures imo white looks the best, would you say the same to your eye as well?

 

[Things]

The laser lines look crazy good through the vortex - it's like a flat time tunnel type effect.

From the pictures imo white looks the best, would you say the same to your eye as well?

Yeah, seems to give the best contrast. I'll be using a 520nm laser in it permanently as green is better than red and 445 though.

 

[Things]

Done a bit more work on this, it's pretty close to completion

Mounted the electronics on their panel:

"Interface" is simply a RGB LED to indicate things like when the reservoir is empty/full etc, a RJ45 jack for the remote, and a power input.

I had originally just glued all the edges of the base together, though even after a short time so far most of the edges had split. I decided to just use screws instead. As a result, the "top" panel of the base no longer fit in. I had to trim down a couple of edges - which also chipped the paint off them The fog holes were also beginning to swell up already - so I decided if I was gonna bother re-painting it, I'll just go for the acrylic option.

Had a nice large circle made up in 3mm black acrylic, and drilled a bunch of holes in it (in a cool pattern, too )

Works and looks awesome

Also means I can get easy access inside the base for cleaning when it eventually needs it. I also decided to run the wires to the lights/fans at the top through one of the pipes, so there's no wires running down any sides

I also purchased a couple if Philips 7W LED downlights - rated for 4000K at 36° beam angle - luckily it seems they will run on 12VDC fine, however they don't like PWM at all, so they're just stuck on full brightness for now. I like the slightly cooler colour than the halogens, and it seems to have less "splash" around the outside also, pretty pleased

Lights look a bit warmer in the pic than they actually are.

Just need to touch up the paint and it's basically done

 

[Sigurthr]

Looks really awesome.

I wonder though, if you used cooled vapor (so it sinks), could you invert the system and have the wide end of the funnel at the top?

 

[Things]

The vapour is just water vapour (not steam), so it does sink already

And yes, you could. However it'd be a lot more work to make it .. functional, I guess. The fog condenses on almost anything it touches, so you'd have water dripping from the top you'd have to contain, and also the fan at the bottom, which said water would drip into, and also fingers could go into as well

However seeing as the "updraft" would actually be at the bottom, it wouldn't be as fun putting objects into it.

I'm curious if you could somehow prevent the fog being sucked straight into the fan, whether just the fact the funnel is low pressure would drag the fog down to the base by itself.

I've definitely considered doing that though .. something fun and unique to try one day.

 

[Things]

New vid!

 

[Things]

Redid the fogger water container yesterday, originally I had planed to use a gravity feed to keep it topped up, so the water inlet was at the level I wanted the water to stay at. Since I switched to a reservoir and pump, filling the reservoir past the fogger tank water level meant it'd just siphon straight into it! So had to redo the container and move the water inlet higher so it wouldn't siphon.

I think I'll have to switch to using distilled water though, the amount of gunk that had collected in the fogger tank was insane, and the fogger disks look like they're already partially ruined. Couple more pics:

 

[ped]

Could you turn that thing upside down so the wider part of the funnel is at the top?