LED grow light

kamko15

I couldn't Edit the previous post so heres the diagram again this time the wiring may look a

little more correct.

Greg-ulate

Very cool project! I hope you are learning a lot about electronics along the way.

The array calculator in the original post is very cool as well. my suggestion is that you dont necessarily need to connect adjacent LEDs to eachother electrically, you could group them by color and then use the LED array calculator to determine how many rows you should have and what resistance to add in each row for current limiting.

to make these currents more similar you could wire 2 of each 350mA LED in parallel, so that 700mA total would flow through the combination, providing more current to the 750mA LED, boosting its intensity.

If I were going to design something like this I would probably use something like an old PC power supply to get 12V, wire as many LEDs in series as I could such that the combined forward bias voltage drop was about 10V, put a little LM317 as a constant current regulator, and then repeat that as many times as I need until I have the right amount of LEDs. That way it would be super cheap. ~$20 for 50 LM317s, ~$20 for the power supply (unless you have them lying around like me) plus the cost of the LEDS and mechanical components.
for a regulated current of 350mA us a 3.6 Ohm resistor, for 750mA us 1.6Ohms

kamko15

Hey guys. Thanks for all the posts and advice, but I have a specific question I need help with.

if you look at the most recent diagram you'll see I'm planning on using

10 constant currant drivers to run each series of 7 LEDs in parallel. Okay got that figured.

Now i'm having issues with the power supply. I don't know how I am going to wire all of

Those currant drivers to one power source. please if anyone knows please reply.



Jim, I saw that my LEDs weren't the same currant and am now looking for replacements.

Greg-ulate

The LEDs not being the same current will not be a problem if you group the LEDs together by type and configure the constant current supply to provide exactly the right current for each type.

The Warm White LED from Superbrightleds.com looks like it provides 180 lumens for 3 dollars each @750mA, and the one on newark says 80 lumens for 8 dollars, thats less than half as much light for more than double the price.

the constant current drivers can all go in parallel with eachother, as long as the power supply is capable of handling the sum of all the currents. I hope you dont spend too much on the current drivers, the method I suggested would require about 1 dollar each

kamko15

Hey guys I'm about to begin purchasing LEDs. when I'm all done Ill be sure to let you know prices.

But! alas i cannot move forward with this project, because I'm not sure how to wire all of the

constant currant drivers to the 24v power supply.I need to wire 10 parallel connections, and

for them to be parallel each driver will need to be directly connected to the power supplies

+ and - output. I haven't seen this done and am wondering if i just strip the + and - wires

then just "tie-in" or wire each positive and negative end of the driver to each singular

+ and - lead from the power source.

In my search for power sources I came across ones that said dual output. I am wondering if

I need multiple outputs, or if dual means it can hook up to two different arrays.

Please answer these questions specifically so I can begin to order a power supply.




power source in consideration

kamko15

LED SPECS

RED-1watt/2.0-2.6Volts/350milliAmps/40-50Lumens/620-630nanometers/120degrees

RED-1watt/2.0-2.6Volts/350milliAmps/40-50Lumens/660nanometers/120degrees

BLUE-1watt/450-460nanometers/3.0-3.6Volts/350milliAmps/15-25LumensM/120degrees





the attachment is the bill from the LED company. see how I did.

Attached Files

recepit for 1Watt LEDs(msgboards).xls (32.0 KB, 8 views)

NascentOxygen

The constant current drivers can all be powered from a single pair of output terminals, provided the sum of the currents is within the current rating of the power supply.

I suggest that you fabricate only one current source to start with, and concentrate on getting it working and powering its group of LEDS.

kamko15

Thanks for the reply, but could you be a little more detailed. Maybe you could you tell me if

the diagram with each driver separately tied into the output terminals is correct or if thats

not the right way to go about it.


Another question I have for all of the viewers. What gauge wire should I use.??

jim hardy

sketch on left is fine.

# 18 lampcord is easily good for 7 amps

kamko15

I recently got some help from customer service representative Deng Tianxiong of Kutop.com. He sent me

the diagram below, and said this was the method to wire parallel circuits to the power source.



Is the above diagram more correct than the method I was originally going to use

depicted in the diagram below?



In this diagram each LED drivers positive and negative leads are connected to the positive

and negative leads of the power source output. In Deng Tianxiong's however each LED

series is wired together positive to positive, and negative to negative.

You guys have been a great help so far and Im asking again for your help. Thanks in

advance!

jim hardy

Imagine it as a plumbing problem.

Supply pipes are red and go to positive of supply, by hook or crook.
Drain pipes are blue and go to negtaive.

The two drawings you propose are electrically equivalent, just one is a "star" or "Radial" hookup (all wires radiate out from one point)
and other is a "loop" or "daisy chain" where they are strung together like Christmas lights..

use whichever looks better to you and will be easier to repair when that becomes necessary.
Answer perobably depends on where you physically locate the supply.

kamko15

i wanted to keep all of the diagrams the same style so I made this one up.



I'm pretty sure this is what Deng Tianxiong's diagram would look like.

Please let me know if it is or not.

sorry im not sure why but I couldn't resize the picture.

kamko15

Hey guys I havn't made a post in a while, but I have an update on this project.

I got all of the supplies I needed to complete the 70 WATT panel so I went ahead and did it







Looks pretty dam good you might say...WRONG!!
I was really sure of my method so I wired everything up and never stopped to test, and this is what it got me.



I think there are two duds which dosnt say much for the quality of the LEDs, but besides that the series connections dont seem to be working.

heres a few close ups of how I wired them maybe someone could give me a little insight on how to fix this.









P.S. here is the power supply I am using maybe this has something to do with it as well.

dlgoff

Thanks for taking the time to report back.

I couldn't find any reference in the thread as to the wiring definition of the LEDs base terminals. (edit: oh wait. Yes there is. Let me read it first) Guessing here that the green "-" supply should be on the last LED in the string?

jim hardy

what's IN and what's OUT on your LED's ?

Clearly, current is only going through the first one of each string.

One of those wires from each constant current driver needs to go to LAST LED in its string...
so the current will go through all of them before returning to supply.

You had it right a couple weeks ago, , take a look at the sketch in your post of Feb1-12 11:49 PM.
Where's the wire going to last LED, that blue wire at top of panel? I thought you were showing it as 'typical " for all rows.
Looks like you hooked it to first LED instead.

Good thing you had that constant current driver in there !!!

dlgoff

Looks like your green negative supply should be on the last LED. Here's the diagram from your link, with my green and orange annotation.

Attached Thumbnails

 

kamko15

Yeah, Thanks for the replies guys I relized my mistake only after posting. I fixed the problem and am still having troubles so Im turing again to you.

here it is all fixed up




The electrical tape is only temporary.

Heres is it all Lit up.



Even though its not perfect yet, it still looks pretty cool. I also replaced the first two LEDs in line 10 and it is now lighting perfectly.

Problem 1- as you can see the LEDs in lines 1,2, and 8 are lighting but very dimly and Im not sure why.

Problem 2- line 9 is not lighting at all, like power isnt even reaching it.

Im not sure where these problems originate from or what could be causing them, but I need to solve these problems in order to move forward with this project. You guys have been a great help so far and Im hoping that you all have a bunch more advice to give.

P.S. It may have something to do with how the drivers are wired to the power source?