DIY Gas Burst Agitation for 1 gallon vertical tanks

[Jbb]

I'm lucky enough to have a film processing sink & I've been looking at doing this for a while but got hung up on the interval timer, I've found many suitable solutions but they're all a bit messy.
Your solution looks great though, would you mind sharing some more info on it mainly the internals as I have some Arduino coding knowledge!

[Tin Can]

I use 2 timers in series. The most common perhaps 511.

Next time I get out of bed I will show my spares

I have a BAD KNEE this weekend
I

I'm lucky enough to have a film processing sink & I've been looking at doing this for a while but got hung up on the interval timer, I've found many suitable solutions but they're all a bit messy.
Your solution looks great though, would you mind sharing some more info on it mainly the internals as I have some Arduino coding knowledge!

[Tin Can]

Here is what I now use https://www.amazon.com/Comidox-Autom...ps%2C93&sr=8-4

Here is my upgrade I have as spares https://www.amazon.com/Automotive-Di...ps%2C93&sr=8-3

I use 12 VDC inside my box with a wall wart way away from any water

The Timers will actuate small 12 VDC air solenoid https://www.amazon.com/4inch-Normall...ps%2C82&sr=8-3

I have water separator/filters downstream

Use brass fittings with careful application of thread tape

[j.e.simmons]

I have a plenum from an old camera store setup for the 3.5 gallon tank. The downward tube ends in a T fitting and the gas tubing in the tank is a continuous, though zig-saggy loop, not a dead end tube as yours is. This way the gas feeds to both sides at once which should help equalize pressure.

[John Layton]

Ha! True story from my misspent youth...at U. of Rochester, freshman year, me and my buddies had the brilliant idea that we would forge a letter (using U. of R. letterhead) to the local gas supply company for a large tank of Nitrous...detailing how we were running an experiment in the phsyc. lab involving two mice (our second mistake). Long story short...we proceeded to party with the tank, and returned to the gas company for a refill...two days after we'd picked up the first! You shoulda seen the looks on their (gas co. folks) faces! "two mice....TWO MICE?!! Hey, do I look that stupid? Now get the hell out of here before I call the cops!"

[Sam L]

John, you're right -- the dead-end tube didn't end up working well so I replaced it with a Tee version (picture in my second post).

[Sam L]

JBB, happy to share the code, though I think you should do something much simpler. PM me and I'll send you a link.

My solution ended up being clean but is way overkill. If I were to do it again, I'd probably still use an arduino, but:

- No display, only dim red LEDs for "running" and "gas on"
- A simple 3-way toggle switch for run - off - continuous
- No adjustable timing, just 1s on 10s off

That would dramatically simplify it and it would do everything you need.

- I use the same solenoid as Tin Can and common 5V one-channel relays from Amazon driven directly by the arduino. One gotcha is that you have to add a shunting diode for the solenoid or you will fry your Arduino. Mine was rebooting after the solenoid was released until I added the diode.

- I suggest using a toggle switch with a rubber boot for splash resistance.

- The tiny arduino pro micro is nice, though any would work. The pro micro fits really well into small enclosures.

- I fit everything (arduino, display, solenoid, etc) into an aluminum Hammond 1590BB enclosure like they use for guitar stomp boxes and put rubber feet on it keep it above any water sitting on the counter.

- 12V wall wart with a 5V regulator in the box

- 5/16 (8mm) poly tubing (https://www.amazon.com/gp/product/B08GC75P4N) and quick release fittings. Double threaded union to get into the box (https://www.amazon.com/dp/B08XWYGQ14)

[John Layton]

Back on track with this thread (sorry!), I am wondering...in the case of using the (slightly reactive) copper tubing - could you somehow "tin" this tubing after you bend it...to essentially coat/seal it with something less reactive?

[Sam L]

Maybe a plastic coating or electroplating it. The holes in the plenum are so tiny (1/64") that any kind of coating is likely to clog them. They can be cleared out by re-drilling them but it's very easy to break the tiny drill bits if you use them by hand.

I'm not sure it matters -- I don't see any corrosion yet. Since the developers I'm using are alkaline, I don't think they interact much with the copper tubing or its oxides (could be wrong). If it were acidic, I would be more worried.

[j.e.simmons]

My original plenum is plastic. I made another from aquarium air line tubing and glued it down to pieces of an under gravel filter to provide the distance above the tank bottom.