Growing seedlings in home The conditions are quite difficult, since often there is not enough light and space on the windowsills. Even on the south side of the house by the window, the light intensity is within the normal range for growing seedlings only in direct sunlight and clear weather. The solution to this problem can be found in the creation of special artificial lighting, which can replace natural.
Materials and tools that the author used to create lighting for plants:
1) Red LEDs power 3 W and long wavelength 650-660 nm
2) Blue LEDs with a power of 3 W and a wavelength of 450 nm.
(the ratio of the number of LEDs is approximately 1 blue to 2-3 red)
3) Aluminum pipe with a cross section of 20 mm
4) special board with aluminum base
5) heat transfer paste
6) soldering iron
7) wires
8) programmable timer
Consider the main stages of creating this lighting system for seedlings.
To begin with, the author decided to figure out what kind of light is needed for the most productive plant growth. As he found out, for photosynthesis, plants can use the entire spectrum of the light range, but the light in the red and blue parts of the spectrum has proved to be the most effective. In these ranges of assimilation of light by plants, it achieves maximum results. For this reason, the author decided to use light sources in the ranges Sh-DD7, DD5-D50 and 655-660 nm to create his own backlight, and the light from the window can provide the rest of the spectrum.
Further, the author decided to see which light sources will be able to produce such spectra. To begin with, he drew attention to special luminescent phytolamps. They shine with a purple-pink color and, according to reviews, are much more effective than ordinary daytime lamps for plants.
The option of lighting on sodium lamps was also considered, but they emit too much heat, which means that when using them, you will need to make a separate greenhouse, which is very time-consuming.
Therefore, the choice ultimately fell on the backlight using LEDs. Although the LEDs themselves are inferior to lamps in terms of lighting area and price, but they have high efficiency and low power consumption, which will save on the operation of this backlight.
A profile aluminum pipe with a cross section of 20 mm was used as a radiator. LEDs were attached to this pipe through a special board with an aluminum base.It is very important, according to the author, to use heat-conducting paste when mounting the board to the radiator, as well as the LEDs themselves, since overheating of the equipment can lead to a decrease in brightness, and in subsequent failure.
For installation, the author used a powerful soldering iron, since the boards were made of aluminum with the application of tracks and a weaker soldering iron will quickly cool down from contact with the board, and with prolonged heating it will cause the LED to overheat. Therefore, using a more powerful soldering iron using the quick touch technique is safer for equipment. When soldering LEDs, the author chose a distance of about 8 cm between each of them, this is just enough to place about 12 LEDs on 1 meter of the profile pipe. The number of LEDs per meter pipe was calculated so that there was no overheating of the structure. The LEDs were soldered sequentially using a wire with a cross section of 0.25 mm, after which a second solid wire was passed inside the pipe. The operating voltage in the luminaires was about 48 V at a current of 700 mA.
Further, the author began to create power for LEDs, which is carried out through a special unit. Moreover, unlike standard LED lines, where the power is supplied by stabilized voltage, in this case the current is stabilized - and for these LEDs it is 700 mA. Thus, the voltage can vary over a fairly wide range. This is necessary in order not to make a separate power supply for each type of LEDs, since their voltage is different. That is, the red LEDs have a voltage of about 2.2-2.6 V, and the blue ones have 3.4-3.6 V. Thus, the author simply calculated the total voltage of the LEDs on the bar, since the connection is serial and the current is constant, and received 1 tube of 12 LEDs for 1 meter, among which 8 red and 4 blue, the total voltage will be 35.2 V. When buying a power supply, this voltage was taken into account.
After the backlight was ready, the author decided to improve it for ease of use. Since, as the seedlings grow, the backlight must be raised so that it does not burn the leaves of the plants, the author decided to make regulated deliveries that will rise along the hairpin when the homemade lamb rotates. To automate turning on and off the backlight, a programmable timer was installed.
Thus, the backlight was completely completed and the author began to test. During the tests, some shortcomings and features of growing seedlings using a similar light panel were noticed.
The most important drawback of this backlight is its bright raspberry emitted light. Being in the same room with such light for a long time is rather unpleasant, therefore it is better to use the non-residential area of the room for growing seedlings. In the case of the author, a basement was used, and when watering the plants, the backlight simply turned off.
A feature of plant germination under such illumination was also noted. Seeds germinate much faster than under natural light, but then their growth stops compared to the growth of seedlings under natural light, however, after planting in the ground, the situation changes.
In addition, the plant that grew under the LEDs, can not be carried out on the windowsill before planting in the ground. Otherwise, due to a lack of light, it will immediately stretch.