Putting Electronics and Instrumentation degree to use after 14 years

14 years after completing my engineering, old memories of electronics and instrumentation are being rekindled!

All these days i have been slogging and still slogging in IT calling myself Peoplesoft Consultant. My plants has been my stress reliever and keeps me from ageing, backache and heartburn… do get some sunburn though.

After indulging in kitchen gardening, bottle gardening, and rooftop gardening, i have now landed in Aeroponics. Aeroponics is a perfect platform where both Electronics and Instrumentation are put to use. Feeling energized to once again play with pumps, pressure switches, thermostats and electronic circuits. I’m setting up a simple high pressure Aeroponics system. Will explain more details in the upcoming posts. Here is a high level design of my first attempt.

 

Simple High pressure Aeroponics high level design

High pressure diaphragm pump is used. Nutrient solution is stored in the reservoir. The pump is triggered in regular intervals by the timer and the nutrient solution is sprinkled on roots. The unused nutrient solution is sent back to reservoir by gravity. No wastage of water except very little through transpiration.

If this succeeds, planning to introduce pressure tanks, pressure switches and nutrient solution cooling systems.

Organic Aeroponic nutrient

I have avoided using any non-organic fertilizer and pesticides bought from shop for rooftop gardening. I have been using organics like kitchen compost, vermicompost, coffee grounds and tea extracts as fertilizers and ginger/chili/garlic/turmeric concoctions as pesticides. When i started aeroponics, I was tempted to use non-organic fertilizers because predominantly they were used for hydroponic and aeroponic systems and i couldn’t find any references to usage of organic nutrient in aeroponics.

Panchagavya:
But, i stuck with my organic way of gardening no matter what the result is. Never had great results from using panchagavya in conventional rooftop gardening. But surprisingly, in Aeroponics, panchagavya is giving good results. So, I prepared my own Panchagavya… a much cheaper version. 1 ltr panchagavya is sold ranging from Rs.100 to 500 in shops and online. My ingredients:

Fresh Cow Dung – 1 kg
ripe Bananas – 2
Sugarcane Juice – 400 ml
Milk – 200 ml
Curd – 100 ml
Groundnut cake – 200 gms
Neem cake – 50 gms

Have used groundnut cake instead of ghee. I believe ghee is used to increase stickiness when panchagavya is used as foliar spray. Since, panchagavya is mixed in water and applied as nutrient to the roots, i replaced ghee with groundnut cake. Ground nut cake is cheap as well as has lot of nutrients. Traces of neem cake is added to act as fungicide because i have heard a few farmers say that panchagavya encourages fungal infections. Skipped cow urine as i just couldn’t get it. All quantities are approximate.

My aeroponic reservoir has 20 ltr capacity. Adding 30 ml panchagavya in 20 ltr water seems to be giving good results. I guess i have been using too much of panchagavya in container gardening. That could be one of the reasons why results were not good in soil media container gardening.

Jasmine plant transplanted from soil to aeroponics have started blooming.

Jasmine Blooming

Ladies finger or okra (my most favorite vegetable) has started to show out the roots.

Okra rooting

Selecting Timer for Aeroponics

Timer is the key controlling component of an aeroponic setup. The common timers available in the market says 24/7 on it. Don’t get deceived by it. They are actually drip irrigation timers which has a set number on/off times per day. Typically at the max 8 times per day. Those timers cannot be used for aeroponics. Aeroponic system needs cyclic type of timer that repeats the cycle continuously. Heavy duty industrial use timers like “SELEC Digital Din rail Timer – 600DT” are available for around Rs.1200. They are multi functional. Refer the manual and set the interval as needed.

If you wish to do it yourself, it is quite easy to build a 555 timer circuit. It needs to run in astable mode. Here is a sample 555 astable multivibrator circuit. Just add a relay (to run the pump) to the Output Pin 3. I have used the following components to achieve 20 seconds ON (t1) and 20 minutes OFF (t2):

R1 = 47K
R2 = 1M
C1 = 470uF

555 astable circuit

R1 and R2 can be variable potentiometers and you can adjust them to vary the t1 and t2 duration.