"Magical" LEDs let my plants grow faster? (Experiment) The Future of Farming!

It is Winter and that means the temperature  is low, you rarely see the sun and I am   sitting all alone in my greenhouse in which  there are no more crop plants to be found.  “But It doesn't have to be that way”:  thought my trusty electronics partner   Würth Elektronik and promptly sent me a care  package consisting of 4 types of different LEDs.  Those LED can of course not increase the  outdoor temperature or let the sun shine   more often. But they can be used to build a  sort of like indoor greenhouse which supposedly   can improve the quality parameters of plants and  therefore most importantly let them grow faster.  At first sight that obviously sounds amazing but  is this claim of a quicker growth really true?   Is it worth it to use such an illumination  and how difficult is it to pull off?  I will answer all these questions and much  more in this video. So let's get started! This video is sponsored by the  Würth Elektronik eiSos group.  When talking about plant growth then we  can not avoid talking a bit about biology   which loves to throw around complex  technical terms like chlorophyll,   beta carotene, phytochrome and much more.  That is why I want to keep this biology excursion  as simple as possible and recommend everyone who   would love to learn more about the subject  to check out the Würth Elektronik website   or the video description where you can find very  detailed application notes with tons of details.  And with that out of the way let's  get right to the first quiz question:   “Why do most plants look green to the human eye?” I mean with my example here I am using a light   source which roughly represents the visible  light spectrum of the sun and as you can clearly   see our plants appears to be green in colour. The reason is of course that the wavelengths of   the green light which lay between 490 to  575nm are for the most part not required   by the plant organism and thus mostly  not get absorbed but instead reflected.  However the other wavelengths which represent the  remaining colours are apparently more essential   for the plant since they clearly get absorbed. The plant uses this light to mainly drive   its photosynthesis which takes carbon-dioxide  and water and turns it into oxygen and glucose   which the plant organism also uses  for its own energy supply to grow.  And with that thought in mind we  can turn our attention to the 4   different LED types that I received. Their colours are called deep blue,   hyper red, far red and daylight. And the first 3 LEDs colours are special   because their emitted wavelength peaks correspond  with the absorption maximum of the plant,   which is basically the spot where  they can absorb the most light.  And needless to say the fourth  daylight LED covers a bigger spectrum.  This is also mandatory though  because the plant not only needs   additional other wavelengths for  other processes besides photosyntheses   but also because our eyes can more easily  see how the plant develops in this light.  And with that being said the  fundamental theory should be clear   and explain why those particular LEDs can be used  for an accelerated growing process of a plant. That means it was time to face problematic  electronics related question like how many   LEDs of which type should we use, how do we supply  the right amount of current, how can we cool them,   how can we dim their brightness and so on and on. Luckily most of those questions were easy to solve   by a bit of clever thinking and having a look  at the datasheets but since I had absolutely   no experience regarding horticulture LEDs,  I had no idea how many of which type to use.  But I was also partly lucky with that question  because as it turns out Würth Elektronik carries   a lighting development kit that not only comes  with a driver PCB but also a horticulture panel.  And I said partly lucky because while the  LEDs were in stock, other parts of the kit   were apparently sold out and thus I had no  chance of getting the kit at this point.  Thanks to its manual though I at least  got a reference point on how many LEDs of   which type to use and thus I continued  by designing a replica of this PCB.  And even though I was happy with my final  design I was still a bit worried about the LEDs.  You see the LEDs are high power ones which  means that even though they are small,   they can emit quite a bit of light and thus  obviously demand a bit of current as well   with a nominal value of 350mA. The consequence is that it produces a noticeable   power loss in the form of heat. And of course  we have to somehow spread this heat elsewhere,   otherwise the lifetime of  the LEDs could get shorten.  And luckily does my PCB manufacturer offer  aluminium PCBs for one layer designs,   which mine should be, and thus I used  this option to get my hands on those   promising looking aluminium PCBs which will  *spoiler warning* keep my LEDs nicely cool.  And of course I also didn't miss the  chance to include an error into the design.  But besides that everything worked out just fine;  spreading the solder paste with the stencil was   no problem and also using hot air to reflow  solder the LEDs turned out to be successful   even though I think using a hot plate  for reflow soldering would have been   more appropriate for such an aluminium PCB. And once I was certain that all LEDs functioned   correctly, it was time to think about a circuit  that could supply them with a constant current of   350mA and that I could also pulse in order  to dim the brightness between 0 and 100%.  I of course chose an Arduino to create  the PWM dimming signal and also 4 LED   step down modules from Würth Elektronik. These modules are in a nutshell small   switched mode power supplies that require  very few complementary components around them   in order turn a variable input voltage  into a constant output current.  And since we can adjust the  brightness by pulsing the DIM pin;   everything should work out just fine. That is why next after creating the   fitting schematic, I designed a second PCB as a  driver PCB around the just described components.  As soon as the PCBs then finally arrived at my  place, I once again used the hot air technique   to solder the LED drivers into place and  then switched over to a normal soldering iron   in order to secure the remaining SMD  and also THT components to the board.  The result did look promising but before I could  test anything I firstly had to write a bit of   code for the Arduino that generates the 4 PWM  signals which I then obviously had to upload.  After then checking the PWM signals; it was time  to connect all the LEDs and power the whole system   with 19V and as you can see I think my soldering  technique was not suitable for the LEDs after all.  But luckily while I was about to fix this  problem, the lighting development kit from   before was back in stock and needless to  say it comes with a horticulture LED panel   that I can use and best of all it even comes  with a lens that focuses the light better.  Now the kit also came with its own LED driver PCB  which seems to be more sophisticated than mind   and even supports Bluetooth but I decided  against using it because mine works just fine.  And just like that the electronics  sides of things came to an end and   it was time to start the actual experiment  which began by selecting suitable seeds.  I decided on Arugula because it not only grows  fast but also because its delicious and nutritious   which fits well with the topic of  horticulture which is all about the efficient,   profit-yielding and sustainable production of  food for a growing population in the future.  So I prepared 6 containers with seeds of which 3   will have to live with only the sunlight  while the other will be continuously lit up   by the LEDs through the help of a rustic  wood construction that I build beforehand.  But here comes the question how the individual  light channels should be mixed together   and let me tell you that there is no universal  answer to that because every plant comes with   other light tendencies and thus an individual  fine adjustment is kind of necessary.  It is also noteworthy that during  different development stages,   the plant requires different wavelengths.  But since we are only doing a simplified   experiment here and because the manual recommends  a blue red mixing ratio between 50 50 and 90 10,   I made my life easy and went with the  middle value and adjusted the remaining   LEDs to get a nice to look at end result. And just like that I started the experiment.  It is mentionable that all plants were watered  with the same amount and I also took care to   guarantee an almost constant temperature  along with some fresh air from time to time.  And after the first days there wasn't really much  of a difference noticeable between all the plants.  But after only a week the difference became  apparent and became more and more obvious as the   days passed by. And after a total of 21 days so 3  weeks we can definitely not deny that horticulture   LEDs do in fact accelerate the growth of plants  and by the way the Arugula also tasted great.  Of course in comparison to this faster  growth we have to take the energy costs   and costs of purchase into account, but  I think that when fine adjusting all the   parameters for such an indoor greenhouse, it  can be a promising agrosystem for the future.  And since building such a horticulture lighting  system is pretty easy to pull off and you can   always ask for free samples from Würth Elektronik,  everyone can try it out even today in their homes.  With that being said all initial questions should  be answered and I hope that not only I but also   you before the screen learned something new. If so don't forget to like, share,   subscribe and hit the notification bell. Stay creative and I will see you next time.

Channel: GreatScott!

Views: 390,044

Keywords: grow, growing, light, lights, led, LED, emitting, diode, plant, vegetable, fruit, horticulture, greenhouse, green, house, indoor, plants, experiment, magic, magical, LEDs, how, to, make, project, diy, do, it, yourself, guide, beginner, beginners, electronics, high, power, current, voltage, electronic, würth, wuerth, dim, dimming, brightness, cool, photosynthesis, biology, why, explain, future, vertical, farming, farm, soil, greatscott, greatscott!, arduino, microcontroller, driver, constant, pcb, design, alu, aluminium, lens, test, adjust, colour

Id: 4FryMPpJG6I

Length: 11min 14sec (674 seconds)

Published: Sun Feb 20 2022