High Efficiency LED for Joule Thief, etc.

[MarkE]

Back in 8th grade, I bought al laser diode and I think it was 7 9v batteries and built a circuit from a book at the library.  I think it was only 10khz operation. But the book explained that the pulsing circuit enabled the lasing function. Dont remember the wording on that for sure.  was back in 78.  But later I played with the idea of getting an led, 10m red radioshack, to produce the lasing function.  It was like a region of pulsed current operation that gave some turbo to the output.

Those 10mm reds produced a half decent image of the square chip on a wall.  Use a magnifying glass and it becomes so visible in detail, you can see on the wall/white paper the anode wire and a darker spot where it connects to the chip.

When I pulsed it trying diff freq and input levels, when you get close, you will see just one side of the chip emit a much brighter light. Increase input very gradually and another side brightens, and so on till all sides are kickin. 

Dont remember if it was necessary back then to get the lasers to work properly, and now they can just be dc in, but the effect on the led can be had regardless. The JTs are possibly pushing the leds in this lasing region.   The laser diode I used was IR and I used a dental exray test card from my uncle to see the beam. But when the batteries got low, the beam would sorta fall out and perform more like an IR led and no coherent beam.  Lol. Actually tried to file the side of an led, cutting away some of the alum bowl that holds the chip, to hopefully get a beam out the side. Very wishful and ambitious thinking. Was very careful with what tools I had. But always seemed to kill or short/damage the chip before I could end up seeing light from the chips edge.

IR lasers were $27 back then. Red were out of my price range. Way out if I remember correctly.

Mags

Ordinary LEDs do not operate as LASERs.  JTs are essentially boost mode DC-DC converters.  When the voltage is greater than LED Vfw the LEDs light.  Current to an ordinary LED can be managed with a simple current limiting resistor.  That is entirely impractical with a LASER diode.

[Cherryman]

"I do understand that PWM would NOT be acceptable for growing crops ,you can trick the eye But not mother nature [thx Brad]."

Well that would need to be tested. Remember sliders little circuit that emitted high freq and plants near by grew better. What was it, 27mhz?  Leds should be able to produce that, as I think optical fiber data transmission I believe is much higher than that.

There may be a freq of pulsing the led that the plants like and possibly a freq that they dont like.

Most plants, especially when young, their leaves and branches very noticeably reach for the sun and settle down at night.  If they lean away from a freq they dont like, then maybe dont use that freq. The leaning toward or even leaning away from a freq of light would be cool to see if it happens, and would be a quicker indicator of proper, or not, freq rather than waiting for just growth health and speed.

It would have to be tested. But I wouldnt negate the possibility that pulsing them may be beneficial or even no problem at some freq.



Mags

Some people use moving lights or plants to cover more m2 with less light.


So..   a moving light could also be seen as a frequency.
Wind moving leafs in and out of shadow.. is also a frequency.


Although the more light the better i presume..  one might be able to get a descent result with way less energy use by pulsing.

[MarkE]

Some people use moving lights or plants to cover more m2 with less light.


So..   a moving light could also be seen as a frequency.
Wind moving leafs in and out of shadow.. is also a frequency.


Although the more light the better i presume..  one might be able to get a descent result with way less energy use by pulsing.

There should be some maximum intensity of light beyond which there is no benefit and potentially even harm.  As to pulsing I doubt tha it does any good on its own.  We know from experience in northern latitudes that huge plants can be grown when exposed to light nearly 24/7.  So 24/7 continuous light is probably your baseline, and the object would be to find optimum intensity.  Once one has such a baseline, then one can do things like pulse width modulate to try and see if higher yields per average lighting Watt can be had.

[SoManyWires]

There should be some maximum intensity of light beyond which there is no benefit and potentially even harm.  As to pulsing I doubt tha it does any good on its own.  We know from experience in northern latitudes that huge plants can be grown when exposed to light nearly 24/7.  So 24/7 continuous light is probably your baseline, and the object would be to find optimum intensity.  Once one has such a baseline, then one can do things like pulse width modulate to try and see if higher yields per average lighting Watt can be had.

yes the lights would need to be brighter to be able get more in harvest yield when using the same area of space, not accounting for other variables, such as temperature, humidity, c02 levels (though plants can more effectively digest c02 in slightly warmer temperatures), the plants ability to use whatever its given for plant food, and placement in respect to the light source.

there is ways to place the plants to be able to take greater advantage of the light source(s).
one example is the Omega garden system that uses no light reflectors, as it can rotate the plants themselves around the light, rather than using a linear light moving rail system. though cleaning the omega system might be an issue.
this makes good use of light when not wanting to pay as much on the power bill.
the light in that system is sealed to protect from water damage, and is placed in the centre of a vertically rotating structure that holds the plants in place, allowing the plants to move around the light.

there are lots of other different garden designs than that one too that make good effective use of a individual light source.

the concern with a individual light source being expected to become usable light is plants can get burnt from heat radiation
if kept too close to the light, airflow has been used to redirect the heat away from the source by using exhaust venting,
and even venting sometimes is not enough as the plants continue to grow towards light, leading to a schedule for adjusting light distance that becomes more important according to the heat.



am thinking that to get higher yields using PWM more effectively with the same input power, a crop would need to be using twice the square footage in garden space (ground coverage) than to try to expect any kind of greater yield from half the space if using the same input wattage, and would need more sources of light to match the area.

[Magluvin]

I had talked to Chet a while back about indoor gardening, of food, of course.

Here much later on I am going to try a few things.

What I have envisioned is grow modules. Modules that can stack against a wall in an apartment say where you dont have much option for growing food..

The construction material of choice for me is 1/4in pvc board. Light weight, water proof and easy to work with.

Below I have some pics of leds Im going to try.  A 5m real of blue and 5m roll of red.  Also have a role of UV to try with the blue n red. Led spacing is about 5/8in.  Average of about $12 a roll on amazon. Banggood.com even less.

Running the blue and red rolls together use 5.9A at 13.1v. 77w

The strips can be cut at intersections and solder wire to make new connections to consecutive strips. Not sure what size cabinet to make yet, or if it will need all 10 yards of blue n red, along with uv strips.

Its not always that the light has to come from only above the plants. Side lighting helps keep plants short, not having to reach for the light and keeping stem lengths short. More bushy and more nodes for fruit like strawberries, and denser thicker greens.

And if all works out well, the cabinets can be small, stackable, where one could have a full garden on one wall of an apt or room in a house, without taking up much living space.

Will make a new thread if there is some interest shown to do so.


I have some hope for these led strips. It allows easy mounting, self stick, and the ability to easily line the ceiling and walls of the cabinet. And I think its cheaper than what they have out there for the purpose.

Also looking into mylar for added reflection of light. Any light that does not 'end' up on the plant is wasted. Mylar is over 99% reflective. Shiny side of al foil is about 77%. Actually a titanium white paint is better than foil.

Mags