exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

LED help please

Tue Jul 29, 2014 1:51 pm

Project Purpose:
Develop Plant Grow light with 4-8 100 Watt LEDS. LED's run independent of each other, so if one burns out, others don't shut off. Control each LED via the Raspi if possible. Control temperature of the LED's by using a temp sensor and switching a fan on and off when needed to cool.

Notes:

I am new to electronics and am still in the beginning learning phase.

I want to create a circuit that can power 4-8 100 watt LEDS. If possible, control the LEDs via the PI and if one burns out, the others don't shut down. I don't know how to use the formulas yet to compute what I need (ohms law). I chose this project as a learning point for me. As I said, my electronic knowledge is small, so details and explanations can help me understand. I am currently learning electronics, but have not applied it, hence doing this project. Much help is appreciated, and as always, will be giving back when I encounter other noobs that are in my place.

Resources

LED: http://www.ebay.com/itm/1-PC-100w-20000 ... 4897.l4275
Last edited by exzile on Tue Jul 29, 2014 4:44 pm, edited 1 time in total.

User avatar
AndrewS
Posts: 3625
Joined: Sun Apr 22, 2012 4:50 pm
Location: Cambridge, UK
Contact: Website

Re: LED help please

Tue Jul 29, 2014 2:17 pm

For switching that kind of power, you'll probably need to use high-power relays. So you'd typically have a Pi GPIO pin connected to the 'input' of a transistor, and the 'output' of the transistor would be connected to the 'input' of the relay, and then the 'output' of each relay will be connected to each LED.
And you'll obviously need a seriously chunky power-supply! :shock:

User avatar
RaTTuS
Posts: 10565
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
Contact: Twitter YouTube

Re: LED help please

Tue Jul 29, 2014 2:22 pm

100watt is massive for LED
see
https://www.youtube.com/watch?v=BkUGNtYKasU for 10watt
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 2:22 pm

Im thinking a laptop charger for the power supply? Unless any other suggestion?
Or
Is this something I can use to hook up to a power cable and drive the power of the LED's?
http://www.ebay.com/itm/100W-LED-High-P ... 20e77bb2cd
Last edited by exzile on Tue Jul 29, 2014 2:25 pm, edited 1 time in total.

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: LED help please

Tue Jul 29, 2014 2:25 pm

exzile wrote: I am new to electronics and am still in the beginning learning phase.
Please don't take this the wrong way, but that LED is far too powerful. Unless the aquarium is museum-sized!

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 2:27 pm

Ravenous wrote:
exzile wrote: I am new to electronics and am still in the beginning learning phase.
Please don't take this the wrong way, but that LED is far too powerful. Unless the aquarium is museum-sized!
Aquarium contains plants, sorry should've stated that. But thought it was irrelevant.

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 2:27 pm

RaTTuS wrote:100watt is massive for LED
see
https://www.youtube.com/watch?v=BkUGNtYKasU for 10watt
Strictly need 100Watt Leds since product most Lux/Lumens

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: LED help please

Tue Jul 29, 2014 2:30 pm

exzile wrote:Aquarium contains plants, sorry should've stated that. But thought it was irrelevant.
No that's fine, I assumed you'd have plants, fish or other creatures living in there.

But how large is the tank? Eight 100W units is pretty serious...

Did someone recommend you to that particular LED?

User avatar
AndrewS
Posts: 3625
Joined: Sun Apr 22, 2012 4:50 pm
Location: Cambridge, UK
Contact: Website

Re: LED help please

Tue Jul 29, 2014 2:32 pm

If you seriously need to deal with such high-power electronics, then you're probably best off seeking the advice of a professional electrician, rather than trying to cobble together parts you've managed to scrounge off eBay. :shock:
Don't come crying when it all overheats and your house burns down... :|

User avatar
Richard-TX
Posts: 1549
Joined: Tue May 28, 2013 3:24 pm
Location: North Texas

Re: LED help please

Tue Jul 29, 2014 2:35 pm

Are you trying to simulate the light level on Mercury or Venus? The light will be so bright that the fish wont have optic nerves left.
Richard
Doing Unix since 1985.
The 9-25-2013 image of Wheezy can be found at:
http://downloads.raspberrypi.org/raspbian/images/raspbian-2013-09-27/2013-09-25-wheezy-raspbian.zip

User avatar
RaTTuS
Posts: 10565
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
Contact: Twitter YouTube

Re: LED help please

Tue Jul 29, 2014 2:39 pm

mixing water and electronics is often a bad idea - those LED also need serious cooling
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

User avatar
DougieLawson
Posts: 39562
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: LED help please

Tue Jul 29, 2014 2:39 pm

AndrewS wrote:If you seriously need to deal with such high-power electronics, then you're probably best off seeking the advice of a professional electrician, rather than trying to cobble together parts you've managed to scrounge off eBay. :shock:
Don't come crying when it all overheats and your house burns down... :|
The unit the OP referred to runs at 30-36V @ 100W it's unlikely to burn anything down but it may to too bright for the poor blind fishies.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

User avatar
mahjongg
Forum Moderator
Forum Moderator
Posts: 13218
Joined: Sun Mar 11, 2012 12:19 am
Location: South Holland, The Netherlands

Re: LED help please

Tue Jul 29, 2014 2:56 pm

100W of energy is plenty to start a fire! And if you think "but that 100W is all converted to light", then think again, LED's are far more energy efficient than heating up a wire till it glows white hot, but white LED's are still converting 70% heat, and just 30% to light at best!
meaning you have 70 Watt of energy turned into nothing but heat!

http://en.wikipedia.org/wiki/Thermal_ma ... power_LEDs

Also 100W at say 33Volt still means you are funneling 3 Amperes through the wiring, use too thin wire, and see it starting to smoke!

BMS Doug
Posts: 3823
Joined: Thu Mar 27, 2014 2:42 pm
Location: London, UK

Re: LED help please

Tue Jul 29, 2014 3:01 pm

mahjongg wrote:100W of energy is plenty to start a fire! And if you think "but that 100W is all converted to light", then think again, LED's are far more energy efficient than heating up a wire till it glows white hot, but white LED's are still converting 70% heat, and just 30% to light at best!
meaning you have 70 Watt of energy turned into nothing but heat!

http://en.wikipedia.org/wiki/Thermal_ma ... power_LEDs

Also 100W at say 33Volt still means you are funneling 3 Amperes through the wiring, use too thin wire, and see it starting to smoke!
multiplied by 8.
Doug.
Building Management Systems Engineer.

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 3:57 pm

Not for fish, for plants. I really thought that was irrelevant lol, but you guys are worried about the fish.
It is to product a light for plants! I was hoping for some help on how to build such a unit.

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 4:02 pm

What if I drop it down to 50Watt or even 10Watt LED's? Would that be more satisfying for you guys?
http://www.ebay.com/itm/1-PC-50w-20000K ... 2ed0d78167

http://www.ebay.com/itm/1-PC-10w-watt-R ... 2ed0d3dbbf

bbodin
Posts: 70
Joined: Sat Jun 28, 2014 3:23 pm

Re: LED help please

Tue Jul 29, 2014 4:16 pm

How big is your aquarium? Are you sure you need up to 8 100W LEDs?

This is a pretty serious project for someone who is new to electronics. It involves high AC voltage, high current and foremost safety design.

The LED driver board you found on Ebay is bad. Using an open-frame power supply near a wet environment is dangerous. You need to use a LED driver with an IP67 waterproof housing, preferably with dimmable feature by means of 0-10V voltage, 10V PWM or DALI.

By my rough estimate, the project would cost you at least $1K for just the components. If you are willing to spend that much money for a lighting project, it would be wise to hire a professional engineer to do the hardware design.
Binh Bui

Ravenous
Posts: 1956
Joined: Fri Feb 24, 2012 1:01 pm
Location: UK

Re: LED help please

Tue Jul 29, 2014 4:42 pm

Yes lower power (10W) devices sound much more reasonable. You can always add bigger ones later when you know it's going to work.
exzile wrote:Control each LED via the Raspi if possible. Control temperature of the LED's by using a temp sensor and switching a fan on and off when needed to cool.
I guess the 10W LEDs won't need any cooling - just thermally bond (i.e. glue) them under a metal lid on the tank and that might take care of heatsinking. Actually I would suggest you ask the suppliers - they do say email them with questions! What mechanical mounting and heatsinking arrangements do they recommend, for example.

As someone said earlier I think you should look into fairly heavy duty relays if you want the raspi to control them. (If you don't need computer control then just put the power supplies onto normal mains plugs.)

Also the handy thing about using small 10W devices is you can switch them on one at a time to simulate gradual sunrise, if that's necessary.

Finally - if you haven't done this yet - you might want to look around to see what aquarium enthusiasts are doing. Especially how they do waterproofing and wiring and so on. Aquarium stuff can be a big and expensive hobby... (My Dad used to have a 6 foot tank with fish, but that was before LEDs - he used some special fluorescent tubes which were the "best thing" in those days.)

exzile
Posts: 132
Joined: Sun Jul 20, 2014 5:33 am

Re: LED help please

Tue Jul 29, 2014 4:45 pm

So I will start off with 10- 10watt LED's to produce 100W output. Any references to a schematics or how I can do such a thing?

Duane Degn
Posts: 55
Joined: Thu Jul 10, 2014 6:30 am
Location: Idaho, USA

Re: LED help please

Tue Jul 29, 2014 4:46 pm

Do your plants need blue light?

I have a few of these LEDs and they're really bright. One problem with the larger LEDs (30W) is they need to be driven at higher DC voltages than are easily available. I don't think your computer power supply will be able to power more than the 10W LEDs. But 10W LEDs are crazy bright.

I have a 30W LED but my 19V power supply can barely turn it on.

I don't know enough about powering LEDs to be much help. I do know there are special LED drive circuits. This one can be powered by AC but it looks like the most powerful one (from this seller) only goes up to 7W. I'd bet you'll want your drive circuits powered by AC.

You ought to get a couple LEDs to experiment with. I'd start out with 10W and maybe 30W and then decide if you need them to be more powerful. Having a few to experiment with will also give you a better idea of how many you'll need.

Once you have an idea of how to power the LEDs you can start to figure out how to read temperatures and turn on fans (or you could do this at the same time while waiting for LEDs to show up).

Edit: I missed the last few posts while writing mine. I think the Pi can directly control a solid state relay (SSR). You need to make sure you get the correct kind. There are SSR made for DC current and those made for AC. You can't use a DC SSR on AC and vice versa.
Last edited by Duane Degn on Tue Jul 29, 2014 4:56 pm, edited 2 times in total.

User avatar
AndrewS
Posts: 3625
Joined: Sun Apr 22, 2012 4:50 pm
Location: Cambridge, UK
Contact: Website

Re: LED help please

Tue Jul 29, 2014 4:54 pm

exzile wrote:So I will start off with 10- 10watt LED's to produce 100W output.
You do realise how much brighter 100W of LED lighting is than 100W of old-fashioned incandescent bulb lighting is, right? :?
Any references to a schematics or how I can do such a thing?
Not my area of expertise, but I'm sure google might be able to turn up a few hints ;)

As one of the other posters suggested, it's always easiest to start off with connecting up just one or two, and then scale up; than try to connect 10 at once and end up totally confused.

User avatar
rpdom
Posts: 17424
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: LED help please

Tue Jul 29, 2014 5:02 pm

exzile wrote:Not for fish, for plants. I really thought that was irrelevant lol, but you guys are worried about the fish.
It is to product a light for plants! I was hoping for some help on how to build such a unit.
So you are building a hydroponics system, not a fish tank for a whale ;)

User avatar
DougieLawson
Posts: 39562
Joined: Sun Jun 16, 2013 11:19 pm
Location: A small cave in deepest darkest Basingstoke, UK
Contact: Website Twitter

Re: LED help please

Tue Jul 29, 2014 5:03 pm

rpdom wrote:So you are building a hydroponics system, not a fish tank for a whale ;)
With that much high powered lighting it's probably a hash farm.
Note: Any requirement to use a crystal ball or mind reading will result in me ignoring your question.

Criticising any questions is banned on this forum.

Any DMs sent on Twitter will be answered next month.
All fake doctors are on my foes list.

User avatar
rpdom
Posts: 17424
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: LED help please

Tue Jul 29, 2014 5:23 pm

DougieLawson wrote:
rpdom wrote:So you are building a hydroponics system, not a fish tank for a whale ;)
With that much high powered lighting it's probably a hash farm.
That thought had crossed my mind...

bbodin
Posts: 70
Joined: Sat Jun 28, 2014 3:23 pm

Re: LED help please

Tue Jul 29, 2014 5:27 pm

DougieLawson wrote:
rpdom wrote:So you are building a hydroponics system, not a fish tank for a whale ;)
With that much high powered lighting it's probably a hash farm.
Free collaboration is out of the question then. :evil:
Binh Bui

Return to “General discussion”