need LED help please

[cary]

hello y'all, can anyone help me. plain and simply i am over my head. i need a couple of LED circuits. both will plug into 110 house current. they are for the purpose of growing plants out of season and indoors. first circuit is the red LEDs about 250 or so, final # adjusted to simplicity of circuit. diode forward voltage -1.8, diode forward current - 20mA. second circuit is the blue, final # of LEDs about 65 or so, adjust for simplicity of circuit. diode forward volts 2.8, diode forward current 20mA. i have tried to figure these out for myself, but due to my lack of knowledge i don't feel my own circuit would be safe. can anyone help me out ?? thanks

 

[dieplz]

The first thing I would start to consider is your power source. You say you want to run off of "110 house current." How about just getting some type of wall transformer that can SAFELY knock that signal down to a much safer, and beginner friendly low, DC voltage? It seems like you have a simple understanding of diodes/LEDs. Once you get a better power source, it seems like you might be able to make some more progress on your own.

 

[Boncuk]

LEDs

Hi Cary,

connecting all LEDs in parallel would require a power supply with low voltage and high current output.

Considering a fairly strong 9V transformer you could for instance make parallel strings of three blue LEDs in series. With a forward voltage of 2.8V each the total required voltage for each string is 8.4V. Use a 30Ohm (or closer standard value of 27Ohm) as a current limiter for each string. For 22 strings of three LEDs (66 total) the required current is 440mA.

For the red LEDs use five in each string which will give you exactly 9V for a forward voltage of 1.8V each resulting in 50 strings per five LEDs. The red LEDs would consume 1A total using no current limiting resistor.

For a safety margin use a 9V/2A transformer, and a 9V voltage regulator which you can boost for more than 1A (standard for LM7809) using a power transistor.

Boncuk

 

[Torben]

Hi Cary,

What was your solution to the problem? It might be better than you think. Then again it might be a more efficient firebomb than lighting supply.

I agree with dieplz--look into getting wall warts for the power supply so you don't have to worry about the mains voltage. I would think the easiest would be to get 2 of them, both 120VAC in/12VDC out with a current rating of around 1A. Then use something like **broken link removed** to make the LED calculations easy.


Torben

 

[audioguru]

Don't plants need the infrared and ultraviolet radiation from the sun or from "grow lamps" to grow? Red and blue LEDs don't have any.

I just looked at "grow lights" in Google. Most are high output fluorescent (getting old technology), metal halide and sodium vapour.
Nobody uses LEDs because they are too dim.
They all want their lights to help grow the biggest marijuana plants as fast as is possible.

 

[Torben]

Don't plants need the infrared and ultraviolet radiation from the sun or from "grow lamps" to grow? Red and blue LEDs don't have any.

I just looked at "grow lights" in Google. Most are high output fluorescent (getting old technology), metal halide and sodium vapour.
Nobody uses LEDs because they are too dim.
They all want their lights to help grow the biggest marijuana plants as fast as is possible.

Actually (and I'm as much a biologist as I am an electrical engineer--which is also about as much as I am a seahorse) chlorophyll absorbtion spectra appear to spike quite a bit in the red and blue, with almost nothing in the ultraviolet, green, or infrared.

A lot of companies and sites seem quite excited about LED grow lights. They might be pure snake oil. I have no idea; haven't really compared the LED wavelengths to the chlorophyll graphs. Looks at least feasible, though.

Out here in B.C. cops look for grow-ops in houses using thermal imaging to spot the "hot" houses. I bet they're not using LED grow lamps.


Torben

 

[audioguru]

Thermal imaging?
You have a heat problem when your pot plants smoke themselves.

I cooked brownies with pot in them one time, a long time ago. Tasted awful! The entire neighbourhood smelled. Everyone who ate them smiled and giggled for a while.
Including my mother who didn't know.

 

[cary]

hi y'all again, this is very simalar to what am interested in. **broken link removed** . i even purchased one to copy it. but the componets are not listed or labeled. as you can see it plugs right into the wall. anyone out there able to figure it out and give me a circuit diagram ?? thanks again

 

[Krumlink]

LOL!

Wow Audioguru you've had a bit of a wild streak haven't you

 

[Torben]

Thermal imaging?

I guess the regular grow lamps they use tend to make the whole house glow. Maybe the cameras are smoking up too.

You have a heat problem when your pot plants smoke themselves.

Yeah, well, like, they're on this really, y'know, cosmic existentialist kick or, like, something. . .

What?

I cooked brownies with pot in them one time, a long time ago. Tasted awful! The entire neighbourhood smelled. Everyone who ate them smiled and giggled for a while.
Including my mother who didn't know.

Ouch. My mom always said she'd prefer me smoking pot to cigarettes, but she'd absolutely tan my hide if I fed her happycakes. After she stopped giggling, I assume.


Torben

 

[cary]

hi again- uncle, if you google -LED grow lights- i think you will see that LEDs will do it. i personally think LEDs are the future in almost all common lighting. but back to my problem, can anyone help me ?? my wife is givin' me the cackeling on this one. thanks

 

[audioguru]

The LED grow lights kit has 272 LEDs (!) and lights only 1 square foot.
They give a number for the amount of LUX it produces but don't say how many LUX plants need.
I wonder how many LUX come from the sun in summer?

 

[audioguru]

I looked in Google for Sunshine LUX and found out that the LED grow light has a light intensity that is only 4.9% of sunshine.

 

[on1aag]

Hi Cary,

Here's a circuit designed for five rows of 65 leds.
Start with one row and measure the voltage drop accross the 1K
resistor. Later you can add four more rows to complete the circuit.
Mind the polarity of the 100 µF capacitor, the diodes and the leds.
The 10 hm: resistor is a fusible resistor, the 1 M is a high voltage
resistor.

on1aag.

 

[cary]

'lo again, y'all, on1aag, thanks pal !! looks what I need!! any chance you can draw it out as i would plug it into my breadboard, did mention i don't know jack about, but i can plug stuff in. on1aag, if i can repay you anyway, let me know. would you like me to get you a deal on lobsters, i'm in maine and lots of folks like that.
uncle, yes sunshine puts off more LUX, but seems that isn't what makes the plants grow. LEDs seem to give what the plants want, and cheaply too. plus plus.