Electronics Aquaponics Demand feeder lever

Probably the most difficult single thing to deal with in making my demand feeder has been working out the lever.

But as usual I called upon chance to solve it for me.

Thanks chance.

For some reason I remembered playing with a switch I bought when I was making the first version of this demand feeder. The switch was one that is a button, and turns on then off again after you lift your finger.

Its sideways click seemed nice to the touch.

The one pictured (centre front) is the same, but is on an old circuit board. I cant find my original version.



Its quite long for a momentary switch.


The interesting thing about these particular, particularly long momentary switches, is they they do their switching thing if you tilt the button to the side rather than just press it. I just tested this one and it works.

They also work if you press it, but its the sideways switchyness that interests me. It should be perfect as the lever the fish hit, because they can hit it from any direction and it should trigger.




Now all I need to do is figure out which brand they are, and if they all work like that. It might be the case that only some of them do this. It might be a manufacturing error rather than a feature.

Perhaps manufacturing error is too harsh.

Perhaps manufacturing  tolerance would be better.

Either way, I might be able to use it.



120 Things in 20 years - As luck might have it, for the next few days, you might find me in electronics stores with a multimeter, trying to find a switch for my electronic, aquaponics demand feeder lever.

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Thinking Fresh produce

Is it just me or is everyone crazy?

Dont answer that, it was a rhetorical question .

I just picked a stack of cherry tomatoes from my aquaponics system. They represent only the second batch that has made it back to the house. All the others were devoured before the back door. But this time, some made it.

Looking at them in my kitchen has me wondering why we insist on having all our fresh produce being uniform in size, shape, and colour. This is a very "developed world" kind of issue, so if you are more sensible than this where you live, just ignore this post, but in this part of the world, almost everywhere we buy fresh produce only sells perfect looking produce.

I wonder what would happen to prices if they just left out one of the criteria for A grade produce.

For example, size.

The size of a fruit is by far the least relevant thing.

The tomatoes harvested were all ripe, all delicious, and all different sizes.

So why would the four on the right be classed as second grade.

Its because...







We are all crazy.




120 Things in 20 years - Where thinking and forming opinions about everyone regarding fresh produce, is often presented as fact.

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Ten Calories Of Energy To Produce One Calorie Of Food

I just read the article  "The Permaculture Solution – an Interview with Warren Brush". It said "Estimates are that the modern agriculture system uses ten calories of energy to produce one calorie of food."

Fearing that I too may be growing negative net energy food. I immediately looked at the energy costs involved with my soil-less gardens. My hydroponic pump uses 160 watts-hours per day or 137.6 KCal or about 576 KJ/day.   Chris Carr was kind enough to remind me that nutritional calories (KCal) are equal to 1000 chemistry calories (cal).    A chemist would probably use Joules and Kilo-Joules (KJ) rather than KCal.   But the we think of food in terms of KCalories rather than Joules, so Ill keep it in KCal also known as large calories as much as I can.  There were other errors in my first draft,  so heres the rewrite.  Many of my calculations will be done using the Energy and Work Unit Conversion at unit-conversion.info/energy.html. 

I did some research and found a daily harvest of 8lbs of lettuce and 100lbs of tomatoes to be respectable averages for a 100sf garden. So I will be using those figures throughout.
Just for grins lets say you irrigate 100 square feet of garden with 10 gallons per day, and you are pumping water from lets say 100 feet below the surface. 

To calculate the power used to pump 10 gallons per minute 100

P_whp = q h sg / 3960

where

P_whp = water horsepower (hp)
q = flow (gal/min)    = (10)
h = head (ft)              = (100)
sg = specific gravity = (1)

P_whp = 10x100/3960 = .2525whp = 0.04497210699688 KCal/sec
This could also be expressed as 188.2892175745  J/sec which is the definition of a Watt.

If you are following along and checking my math you can use the Power Unit Conversion to find the Power.
Power and Energy are different.  Energy is what is delivered and Power is the rate at which it is delivered.
In the above example we deliver 188 Watts for 10 minutes or 31.38 Watt-Hours



We pump for 10 minute so
0.04497210699688 KCal/s  x  600sec = 26.9 KCal
So how many lbs of vegetables would you need to produce 26.9 KCal
Lettuce is 67.37 KCal per lb so you would need 26.9/67.37 = 0.40 lbs of lettuce per day from your 100 sq ft garden. If you harvest 8lbs / day the net gain is 19.97 times
Tomato is 80 KCal per lb so you would need 26.9/80 = 0.34 lbs of tomatoes per day from your 100 sq ft garden  If you harvest 100lbs / day the net gain is 296 times

Below is a list of common vegetables which I got from http://www.freedieting.com/tools/calories_in_vegetables.htm


Lets put this in perspective of a soil-less aquaponic or hydroponic system:
Lets say you use a 20 watt pump 5 hours a day.
    Thats 20 watt-hours x 5 hours/day = 100 Watt-Hours / day  (W-Hr/day)
    Each W-Hr is equal to 0.859845227859  KCal so you spend about 86.0 KCal to pump water each day.

If you grow 8 lbs of lettuce per day on your 100 sq ft aquaponics garden,
8lb/day x 67368 cal/lb = 538944 cal/day or  ,  538.944Kcal/day

You would spend 86.0 KCal to pump water to produce 538.944 KCal of lettuce.
A return of over 6.27 to 1.  Not quite 19.97 times like soil gardening but pretty good!



How about tomatoes...
Lets say you grow 100 lbs of tomatoes per day in your 100 sq ft garden.   
Let also say you use the same amount of electricity - (86.0 KCal/day).
100 lb/day x 80 KCal/lb = 8000 calories/day
So you would spend 86.0 KCal/day to produce 8000 KCal of tomatoes.
A return of over 92 to 1.  Soil gardening was 296 but this is not bad!

Compared to soil gardening the power efficiency is not as good, but water is also a commodity worth preserving and my guess is any of the soil-less methods will beat soil based gardening several times over.   It gets pretty complicated if you consider that some of the water applied to soil returns to the aquifer but ponics are definitely more efficient with water.  

Back to my hydroponic system which consumes 137.6 KCal per day.  It would need to produce 1.72 lbs of tomatoes per day.  But this is just the power used to move water.  Warren Brush was including the power used to make fertilizers, mine, and apply nutrients, and maintain the crop from start to finish.  Thats beyond the data available to me, but at least it still looks like a positive net gain whether you are gardening with soil or without and probably far better than the modern agriculture system using ten calories of energy to produce one calorie of food.

Aquaponics has a side benefit of fish protein which I have not included, but the energy used to make fish food should be considered.  Bioponics on the other hand is free of any further input save iron and magnesium which is also required in aquaponics.


Ill admit this article was difficult for me,  I feel like I have dyslexia where it comes to keeping units straight.  If you find any errors I will correct them, but to my best knowledge I have presented this correctly.

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Water Storage

As water becomes more difficult to obtain we are going to be forced into looking for better solutions.
This is a section of a modular water wall.

I did a quick search and others are also thinking along these lines and some of the walls are very decorative.  The idea of free or cheap drums is admirable but they are not large enough nor are they aesthetic.
 
Its time to think outside the box.  What about large reservoirs of water under our houses or hidden within our walls which would also be used to moderate temperature with its thermo-mass.

I used to live in a very old house in downtown Tucson.  The walls were built of adobe and they were nearly 3 feet thick.  The hot Tucson summers were quite bearable due to the thermo-mass of these walls even though I had no air conditioning.

If we were to build houses like this our energy and water consumption would both drop.  A stucco finish would make the walls look like any other house except for thick walls, and the comfort would be amazing.  This water could be collected during the rainy season and used later in the hot dry summer months to grow food and ensure a beautiful cooling landscape.

.
A family of five uses  about 1 acre foot (about 325,000 gallons) or (1225 m³) of water a year.  So saving water from your roof top may only make a small difference, but small differences add up.   Right now it costs about $1000 to process that much water from waste water or to build a new reservoir.  

Desalination has been done in other parts of the world and California is going to build a desalination plant in San Diego capable of 50 million gallons (189000 m³) a day.  But the cost is probably going to be twice the cost we are used to.  There are also concerns that the plant will kill fish, but efforts are being incorporated that should solve this problem.

In total fifteen desalination projects using reverse osmosis are proposed along the coast from Los Angeles to San Francisco Bay.  In the past many other desalination plants have been closed due to the high cost of operation.  The plant will use an enormous amount of energy -- about 38 megawatts, enough to power 28,500 homes.  
The efficiency works out to be about 3 kWh for 1 m³or 88 gallons / kWh fresh water.  Sounds like a lot of water, but the reality is this will only provide about 7 percent of the total water needs of San Diego County.   

Another problem I see is that this is going to be privately owned.  I would prefer to see communities own their own water source.

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Heliostat Whats a heliostat

I want to start building a heliostat, with the eventual goal of making a solar tracker, but for now, I really want to just build something that will send light through my window.

Why? You may well ask.

And "Whats a heliostat?" you may add.

A heliostat is the kind of thing someone with a water drop lensed microscope might have used to get some light on the subject*. Early models involved humans, who were forced to point shiny things in such a way as to reflect the light to shiny mens laboratories. Later versions incorporate wind up mechanisms. For a single day device, all thats required is that it turns 15 degrees every hour, as long as you are willing to manually adjust the elevation for the particular day you are using the device,
a heliostat will track the sun so that a mirror will always reflect to the place I want the light.

The solar tracker is like a heliostat, except that the place its pointing at is always moving. (that point being directly at the sun wherever it is. But the solar tracker is for another day. Actually all of this is for a great many days.

For now, Ill be working on a small digital device that controls the direction a small mirror is pointing, to make it always reflect light to a fixed point. Basically a way to bring some natural light through a window that doesnt see a lot of light.

There seems to be a few different ways to create some linear movement. Linear movement being required to lift a side of the mirror to adjust the direction of the reflection in the up and down aspect.. I figure if I can raise or lower one side, and make the entire device pivot around a mast, I should have all the degrees of movement required.

According to the invention engine, one way to create the required angle might be to glue a hinge to a mirror, and mount that to a mast to support it. Tie a string to one side of the mirror, then wrap it around a tiny winch mounted half way up the mast, then tie the other end to the other side of the mirror. That would give me up and down, and then all I need is a way to rotate the entire device, perhaps using a geared motor, and a pulley.

I havent really tackled this bit of the design, but the control of the motors could be done via a PICAXE chip similar to that used in my demand feeder. and some light dependant resistors (LDRs).

If two LDRs were arranged so that when the device was pointing correctly, they were both in full light, but when one became shaded, the motor could be turned in the correct direction to make the adjustment.

A similar arrangement could be made for both the up and down, and rotational movements.

Im off to an electronics store to buy some stuff.



*may not reflect reality.

120 Things in 20 years is busy finding bits of heliostat. 

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