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Microwth - automated microgreen farm

Microwth enables you to grow your own soilless microgreens indoors to add to your meals

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The Microwth is a soilless indoor microgreen farm with build-in lighting and watering pump, the user interface provides an easy way to set a custom watering and lighting cycle - or you could use the default values to grow your greens.

The goal is to create an open source platform to easily grow microgreens with a continuous harvesting cycle without too much intervention. To reach this goal I will test different lighting solutions, create multiple designs with different materials and optimize the growing cycle.

What are Microgreens?

Microgreens are young vegetables with a high nutritional value and a great color and flavor profile. They are often seen as luxury food because they have a short shelve live and should be served fresh. That's why they are generally served in restaurants or shipped in containers without harvesting them.

What does Microwth do?

Microwth will help you grown these microgreens in your own house in an automated way. There's a pump installed to keep the grow medium moist, lighting to provide enough light to grow them as quick as possible, and an user interface with internet connectivity to create custom grow cycles with notifications when there are any actions you need to take.

Microwth construction

Electronics

The unit is powered by the DC barrel jack on the back of the device that can be turned of with the switch next to it, all outputs are 12V and the logic voltage is 3.3V

Interfacing

The Microwth uses a custom controller on the front of the frame. This controller has a I2C oled and 4 navigation buttons to show sensor data, the current time, and to locally edit the settings. These functions are controlled by an ESP12 to be able to add wireless capabilities in the future.

The DS3231 is used to keep time and ensures that the controller is fully functional without an internet connection to check the timing of the outputs.

There's also an I2C and mosfet output, the I2C is used to expand the functionality of the controller while the mosfet is used to control the lights.

Pump control

The I2C interface is also used to connect the pump controller based on PCA9536, this IC has 4 outputs so these are all wired up to a mosfet to possibly control 4 pumps.

Pump

The current design uses a peristaltic pump with a 3x5mm tubing connection and that could approximately pump 90 ml/min at 12V.

Lights

The best lighting options are currently being explored but they will most certainly be assembled in a light unit with passive cooling that is easily mountable.

  • Log #2: Sofware and pump update

    brama day ago 0 comments

    Software changes

    Centered time

    The software now includes a setup to start a growth, this settings goes through the lighting and pump settings. I couldn't quite decide which settings would be best for the pump so I've implemented an interval timer that turns the pump on for a set amount of time.

    This new code version (available on Github) has been cleaned up and the interface is easier to use due to a less nested interface. I've also centered all the text on the display.

    Next up will be adding the pump output over I2C and adding labels in the grow setup.

    Pump and barb

    3D printed tee barb

    I have ordered some tee barbs to split the pump output to all the trays, but since these aren't in yet I will be using a 3D printed barb it's a bit leaky but that's something some epoxy will fix :) I am also waiting the the PCA9536 but I expect these sooner then the barbs so I will just be waiting on them. In the meantime I've been testing the pump to see what happens when you split the pump output. The first results show a 25% difference between the two output, this is pretty significant so I will try using a barb design more like the ones I've ordered to see if that makes any difference.

  • Light tests #1

    bram6 days ago 0 comments

    The first lights I will test are these two Chinese led strips:

    These lights don't have much information on the seller page but they are advertised as grow lights. I will be growing some microgreens under them to see how they perform. microgreens don't need a lot light and too much might even result in too spicy microgreens so they also need to be tasted.

    I started by testing the current draw when I noticed that the current started rising when left on for a while. So I made a small setup to measure the temperature and current at the same time. The results(below) show that both LEDs get a steady temperature/current draw at 44c, and that it might be worth it to add some passive cooling especially for the full spectrum LEDs.

    Setup

  • Log #1: Design rev 1

    bram11/07/2019 at 17:50 0 comments

    Design requirements

    The design of the Microwth has to meet a couple of design requirements:

    • The whole system has to be easy to manufacture
    • The design has to be good looking
    • The device has to be easy to use
    • The devices should be stackable to create bigger farms

    With these thing in mind I designed and manufactured the first version, that will be used to test different electronic configurations.

    Design version 1

    The first design on the right allowed for stacking, but after manufacturing and testing proved to have some design flaws.

    • The growing trays in this design are hard to remove because there's no easy way to lift the trays up.
    • The current lights gave a comparable result to the natural lights but the height could be reduced to increase the light intensity for better grow results or reduce power
    • The closed side panels create a closed look and illusion that it takes in a lot of room, it might also look better if the plants are more visible.

    Improvements in the next iteration

    In the next version, I will include cut-outs to easily remove the grow trays, the height will also be reduced to lower the lights, and there will be an extra cutout in the wooden side panels to create a more open design. This version will also include a pump to automate watering for this the bottom height had to be increased to fit the pump.

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davedarko wrote 11/10/2019 at 10:46 point

Already enjoying the great case design!

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Dan Maloney wrote 11/08/2019 at 16:29 point

Interesting. I've always wanted to do something similar for my chickens, to sprout grains for them so they have fresh greens in the winter. I'll be watching to see how this turns out.

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bram wrote 11/10/2019 at 10:29 point

That's an interesting application I hadn't thought about, have you grown sprouts for chickens yourself? How much of these sprouts do you need to feed your chickens or are they additional?

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Dan Maloney wrote 6 days ago point

I haven't actually ever fed sprouted grains because I never built the sprouting system. Those vary considerably, from stacks of 5-gallon buckets to trays similar to your design. Basically the idea is to take some kind of seed - usually wheat berries - and spread it out in a layer in some kind of shallow container. You add just enough water to hydrate, then let it go a few days to a week, adding water as needed. The grains sprout and grow a bit into a tangled mat, which you throw into the chicken pen for the, to devour - it's like crack to chickens. If you're clever about it, you can sort of "nest" sproutings so that a fresh batch is coming ripe every day, so the chickens always have fresh grains through the winter. Eggs from chickens eating fresh greens are much better than chickens fed soy and corn based feed. Even if you just supplement their regular scratch grains and feed with sprouts, it really helps.

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