Wall Mounted Hydroponics (In Progress)

 Wall Mounted Hydroponics

 

 

For Christmas this year, my wife wanted me to build her an indoor hydroponics system. During the summer months we always plant a garden, even if it's small. We love the fresh vegetables and herbs, and it adds a really nice ambiance to our backyard. But when winter comes, and we have to give all that up, we struggle through without fresh mint. It's probably the hardest part of winter. Though, I do hear a lot of complaining about the cold...

When she mentioned the idea of building one of these, I was immediately interested. There is something special about combining digital control with fluid handling, to grow plants inside. And if there is one thing I can't pass up, it's the opportunity to significantly over complicate the process of obtaining tomatoes and basil. 

My hydroponics system is a combination of nutrient film technique, and ebb and flow. Using PVC for the main structure, and nylon tubing to pass the nutrient around.

Netcup Standoff

From the outset, I wanted to incorporate 3D printing somehow. I own three 3D printers after all, so I'm going to have to incorporate those into every project from now on I think... To that end, I came up with what I think is a fairly clever use.

Plants are grown in some sort of growing medium, held by a plastic net cup (black, in the below picture). It's very important for there to be some space between the top of the water, and the top of the roots, to allow them some room to breathe. Since they normally can extract oxygen from the moist dirt, it's very possible to drown a plant if the roots are constantly and fully submerged. 

So, to keep the net cup out of whatever water sits in the pipe, I designed these standoffs. They hold the netcups a few inches above the water, and the plants roots will eventually reach down to access the nutrient.

In this picture, you'll see two different sizes of standoffs. As I mentioned before, it's a combination NFT and ebb and flow - for very young plants that don't yet have long roots, you can place them in the short standoffs and when the pump runs to replenish the nutrients, it soaks the growing medium of the shorter ones. (At the moment I have the pump running once per day.... I don't honestly know what a proper cycle should be yet)

 

 

Hidden Nutrient Reservoir

It was made very clear to me, that the nutrient reservoir should not be in the dining area, but instead should be behind the wall in the pantry. That meant of course running the hoses through the wall. And, as you can imagine, this was the perfect time to use my 3D printer for a wall plate to make the holes in the drywall less drilled looking.

 

 

It does actually add a nice polished look to an otherwise industrial looking focal point of the room.

In the below picture  you can see the mess of wires and hoses that interact with the nutrient reservoir. I think putting all of this behind the wall was the right call in the end.

I have a basic submerged pump, an air pump to keep the water aerated, and a fish tank heater to keep the water at 78F, since it's winter and I'm hoping a little boost in temperature will help them grow more consistently. In this picture you'll see a couple of wifi plugs. These will get swapped out my a more complex system. At the time of writing this, I have no yet completed that, but we'll talk about the strategy in further sections.

 Worth noting, is that the system does not drain as fast as it pumps. I used the same size hose on the inlet and the outlet, which may be the contributing factor. So it is paramount that the pump does not run for more than a minute at a time, otherwise I will easily get overflowing. An attempt to remedy this was to add an air vent to the outlet. It seemed to help a little, but not nearly as much as I was hoping that it would.

Control System

Just like I can't avoid inserting 3D printing into every project, it's also hard to avoid adding some kind of digital/electronic/control systems as well. The WiFi switches weren't working very well for me any way, and I've wanted to build something like this for quite some time. 

The overall plan is to build a four switched outlets powered by a RaspberyPi Pico W. With four inputs for connecting temperature probes (or other sensors) if needed.

I started with the electrical work, routing power through a bank of relays. As well as a 5V power supply for powering the low voltage side.

And that's as far as I've gotten! As I progress I'll update this.

Bill of Materials

Nearly every thing I used was pretty easy to source. Here it is:

Main Structure

1. 8ft of 3" PVC
2. 4 x 3" end caps
3. 4 x 3/4" reducers
4. 4 x 3/4" x 1/2" push fit elbow
5. 4 x 1/2" NPT to hose barb
6. 20 ft of nylon tubing
7. Shelving brackets

Nutrient Handling

1. Water pump
2. Air pump and stone
3. Aquarium heater
4. Food safe bucket
5. Wifi switches (If not using the custom system) 

Control System 

TBD

Model Rocketry! First Steps.

After hearing about a friend of mine who recently planned a date that involved home made model rockets, I decided to delve a little deeper into the study myself. Can I just say, building homemade rockets is the greatest date idea I have ever heard? I mean, it combines nerdy endeavors with excitement, hands on activities, and the opportunity to show off that you know how to make hot gasses expel at hundreds of feet per second out the end of a PVC pipe. Yeah, someday I'm going to try this.

In the mean time, I'm going to do what I do best, and delve into a little self study.

There are two main types of solid fuel I plan to use. The first is known as "Candy Rocket", because its primary fuel source is sugar. The next, more powerful, rocket fuel is known as Ammonium Perchlorate Composite Propellant (APCP). It is, in fact, the same solid rocket fuel used in the shuttles Solid Rocket Boosters (SRB). It's more complicated to build and use, but is significantly more effective than a candy rocket.

One thing at a time...

For a candy rocket, there are a few important ingredients..

• Potassium Nitrate. Used as the oxidizer. There may be better oxidizers out there, but this is the one I am most familiar with. It's also easy to obtain.
• Sucrose/charcoal. Gotta have a fuel. The sugar also acts as a great binding agent.
• Iron oxide/Sulfur, burn rate catalysts, increases the rate of combustion. Leading to a greater acceleration. Unfortunately, this also means the motor's burn time is reduced. Over all performance may not be affected. 
• Aluminum powder may enhance performance of the rocket by acting as an "opacifier", or to increase the exhaust temperature.

To construct the body of the rocket I plan to use PVC tubing, with a caste nozzle made out of water putty. Water putty probably isn't the best material for the job, as it isn't designed to hold up to temperatures such as are found inside the combustion chamber of a rocket engine, but from other peoples experience, it seems to work just fine. Lots of great info on the construction method can be found here.. https://sites.google.com/site/airwavershr/Home/rocketry. Kitty litter is supposed to be a great way to cap the end of the fuel. I'm not sure how that's supposed to work, but I'm willing to give it a try.

One of the key goals of this model rocketry endeavor is the telemetry module. It would be so cool to be able to capture 6axis telemetry, and analyze it post-flight. There are four main components that make up the telemetry module. they are:

• 6axis MEMS device
• nrf24L01+ wireless module
• SD card
• msp430 microcontroller (It's what I had laying around!)
• Battery

Each of these components will be housed in the nose cone of the rocket. They somehow need to be protected from the inevitable impact with the ground. It may be unrealistic without an ejection charge, and a parachute, but I'm going to try. A Styrofoam cone with steel bailing wire reinforcements aught to be enough to withstand the impact. If the components could be housed partially in the PVC body, and the reinforcements transferring most of the shock to the body, the likely hood that the components will survive is increased.

The range on the wireless module might be somewhat limited when it comes to highflying rockets. In which case an EEPROM or SD card to store the telemetry may proved a better solution. It's not as sexy as live data though. An ejection charge and chute may be required for easy recovery.