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I'm not using a constant current but the laptop adapter will only output 3.42A max so should be fine for the 3 leds in the circuit. I think thats right but i'm kind of a novice at this so please correct me if i'm wrong. I believe the driver unit also regulates voltage and current (i have them turned down to min) so i'm assuming the leds wont take more than is regulated but if i was to go to far with those limiters (too much current) then it might blow something.

Edit: so I braved the laptop adapter and we are still alive. It output a lot more light but the heatsink gets considerably hot, i'm guessing around 70c since i couldnt touch it. I'm not really feeling safe about running it that hot so until i can find a lower ampage power supply i'm back running it on the 12v adapter at 1A, roughly 20W.

Also I'm noticing my first led in the circuit is much brighter than the others is this normal?

 

 

It sounds like only luck has saved you from having to get some new LED's.

 

They need a constant current. The module I pointed to earlier does two things.

 

1) It's a step up (Voltage) unit so it allows me to use whatever PSU (within reason) I have around. My LED's settle out at around 34V (~ 3LED's x 12V each). I can't remember if I used a 12V or 19V PSU.

 

2) It allows me to set the current flowing through the LED's at a constant rate. Say 1.2A (1.2A x 34V = 40W total)

 

You would have to photograph or diagram up your set-up for more comment but it sounds as though your LED's are running on luck atm. 

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I think I have the 3 LEDs wired in series already but will post photos later to make sure I'm not doing anything wrong.

HUD the driver unit I refer to is the one you linked earlier, im not really sure what it is/does but it's referred to as a boost converter. I assumed it just converted mains to 12v and regulated current so it doesn't go over. I have the limiter screw's turned all the way to minimum but couldn't seem to get the current down (amps) down below 3 on my unit. Even at min it still reads 3 amps with the laptop adapter.

Will get some photos uploaded later thanks.

 

EDIT: Here are some photos of how its all set up.

 

IMG_20151029_1203201_zps4xh95f9m.jpg

Using 12v Adaptor

 

IMG_20151029_1203111_zpskusywgtr.jpg

*Close up of LEDs. My eletrical knowledge is pretty basic but am i correct in thinking i have wired them in series?

 

IMG_20151029_1145581_zpsopympbgt.jpg

*Close up of 12v power adaptor

 

IMG_20151029_1202561_zps3wvaa6yc.jpg

*Voltage reading of 12V supply using multimeter (reads 16.74V). I'm guessing this drops within 12V when LEDs are on although i havent checked!

 

IMG_20151029_1250531_zpsilphp9vi.jpg

*Current (Amps) reading using multimeter (reads 0.93A). This is with the LEDs on.

 

IMG_20151029_1220121_zpszy9he2yd.jpg

*Close up of 19v laptop power adapter

 

IMG_20151029_1217381_zpsldpqktfn.jpg

*Voltage reading with laptop power adapter 19V (reads 18.82V)

 

IMG_20151029_1251321_zps5fvoy6nm.jpg

*Current reading (Amps) with laptop power adapter (reads 3.97A). This is with the LEDs on.

 

So thats pretty much it. The 12V seems perfectly fine to me it should be sufficient but i'm not sure if its enough light for plants. I can kick it up some but the adaptor is rated at a max of 26W so its probably a bad idea. Now the laptop adaptor i'm almost certain is too much power (3.97A) and i cant appear to reduce it using the boost converter limiter screws so i've given up on that one. Still got some boxes to search later but i think i'll probably end up buying one off ebay.

 

I should also note i get the same issue with the first LED being brigther than the rest with both adapters. I was wondering if its because i havent closed the circuit on my last LED, should i have wired the positive to negative?

Edited by MarkB
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Think I've spotted the problem. It looks as though you have them wired in parallel.

 

This would be consistent with your 'symptoms'. Each LED should have around 11V (total in series something like 34V) across it but your driver module can't give less than you put in, 19V.

The psu is delivering pretty much all it can currentwise.

 

The top diagram is how yours looks to be wired and the bottom one is how I think that you intended. It isn't too much of a change so shouldn't require dissasembly.

 

re-wire.jpg

 

Hope that helps

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Thanks Hud that has indeed solved my issues and i now have consistent light across all LEDs with them wired in series.

 

With the 12V adapter i'm now getting around 700mA roughly 27W which seems to be its limit.

 

When i wired up the 19V adapter i had no light at first but steadily as i increased the current they came on. I decided on 1.2A as that seems to give off a nice amount of light. I calculate that at just over 68W although my energenie is reading 52W at the socket (cant be accurate).

 

So i'm going to stick with the laptop adapter now everything is working as intended. I may or may not reduce my current yet as the idea of using LEDs is all about keeping the bills down but it ultimately depends what the plants like. I'll mainly be growing sundews at this time of the year so i dont know what light requirements are for those. Time to experiment!

 

Hope my novice mistakes help someone else :P. I still have to figure out a way of securing and mounting the booster converter but i'm sure i can figure that out on my own now :D.

 

Thanks again everyone that helped me.

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I've dropped my potential 54W set-up down to 30W. The Neps were getting sunburn and the Heli's were getting nice and red. Hopefully I've found a medium, for my set-up, that works for all.

 

With the CC/CV adaptor there is a one-off set up. Wind the current and voltage (anti clockwise) back to zero (you should hear faint clicks). Connect up the circuit with your meter inserted (series for current) into the return leg and set it on the 10A configuration (if your meter has one - most do).Gently wind up the voltage until you get some light. Then start to increase the current. (From there it is much easier if you have two meters, one for current one for voltage but it can be done well enough with one (current)).

 

Just tweak each (gently) until you have (with your 3x18W LED's) something like 1.2A flowing and altering the voltage doesn't have much effect (34V or so?). Leave it at that 1.2A (measured) x 34V (guessed)  = around 40W. Your LED's should take 54W but you need to be more accurate the closer you get to that limit. I would guess that 40W will be fine, allowing a bit of error on the set-up, and possibly too much for your plants, but I will leave that to you.

 

Glad that it all sounds to be working. I don't think that you will disapointed with the results. Nice, family and living space freindly, set-up that plants seem to like too.

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For those viewing this thread that don't understand whats going on here ...

 

LED's are not like regular lamps (bulbs), they are semi conducting devices.

 

This means that, for a given current and temperature, they will always have a set voltage. This may seem 'counter intuative' but it works like this ...

 

At a given current the LED will (approximatly) have a predictable voltage across it. Unlike a traditional 'lamp', it matters not one jot how much you attempt to increase the voltage. The Voltage will, at double the current, stay pretty much the same. Blown LED.

 

To light one (50W rig) long term you need to control the current, to a large extent the LED controls its own voltage.

 

If you have an LED that the manufacturer rates at 1.5V 100mA then, with a 5v supply you can simply stick a resistor into the circuit. This is OK at the kind of power (heat) you will have to dissipate in the resistor. 5V-1.5V * 100mA. Once you start dealing with 50W LED's then sticking a resistor in series is a problem and you need a more sophisticated set-up to 'feed' it.

Edited by Hud357
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So it was as I suspected too...

 

I've dropped my potential 54W set-up down to 30W. The Neps were getting sunburn and the Heli's were getting nice and red. Hopefully I've found a medium, for my set-up, that works for all.

 

I have also found that LEDs are very efficient, and you don't really need much power for coloring. For deep red, very little light is required to get good results. I'm not really sure about the recommended ratio of 1:4 to 1:8 blue/red light for plants. With that amount of red, my plants get burnt. Plus white light if course.

 

 

I use my fixtures at about 30-40 % power (max. combined electrical power about 30 W, adjustable for each color separately) which gives good results already. Of course it also depends on the distance from the plants.

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With the 12V adapter i'm now getting around 700mA roughly 27W which seems to be its limit.

 

With the LED's Wired in series, the adapter should give you any current (and voltage - bear in mind that you are dealing with semi-conductors) you want.

 

The adaptor should 'give' a lot more than 27W. At 50W mine never even warmed up.

 

(nothing to do with MarkB...)

 

Something for readers to consider is that wiring LED's in parallel opens one up to 'cascade failure' (or a 'complete shed collapse' as we call it in the trade).

 

It works like this ...

 

Your three parallel LED's are taking (a constant) current (let's say 3A total/1A each). One goes down, now two LED's are taking 1.5A. LED 2 now 'blows' and LED 3 is left with the full 3A and doesn't last long. Cascade failure or shed collapse - call it what you will. All three LED's burn out quickly in sequence.

 

The point here is that wiring the LED's in series can protect the circuit. It is not guaranteed that an LED will fail in any particular manner however (open or short circuit) and so you must ensure that you have included appropriate fuses/protection.

 

Another issue is that  'lap top' PSU's are not 'isolated' from the mains supply and so all exposed metal work should be separately earthed. Always think of the worse case scenario ('shed collapse') when examining any mains powered system.

 

Practice 'safe electricity' at all times - always wear a condom (fuses / earthing / RCB's etc).

Edited by Hud357
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So it was as I suspected too...

 

 

I have also found that LEDs are very efficient, and you don't really need much power for coloring. For deep red, very little light is required to get good results. I'm not really sure about the recommended ratio of 1:4 to 1:8 blue/red light for plants. With that amount of red, my plants get burnt. Plus white light if course.

 

 

I use my fixtures at about 30-40 % power (max. combined electrical power about 30 W, adjustable for each color separately) which gives good results already. Of course it also depends on the distance from the plants.

 

 I just ignored the red/blue ratios (most 'white' LED's are made from red/blue anyway). If one were a commercial grower then these things may be important but in my living space a nice warm white is OK.

 

The plants seem to be OK with it too. I have ramped down the power lately for much the reason you suggest. They were getting a little too red.

 

The whole set-up provides a nice light to the room that allows me to not turn on main lights. Couldn't ask for more really. Plants happy, me happy.

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I bought one of these modules for my tinkering.

http://www.banggood.com/5A-Constant-LED-Driver-Battery-Charging-Module-Voltmeter-Ammeter-p-917524.html

Ignore the small plugs on the photo. There are terminal blocks on the lower printed circuit board. If you use an old laptop power supply and remove the 19 volt plug and bare the wires you can insert them into the terminal blocks.

The LED displays show voltage and current so it is easy to calculate the wattage ( Amps X Volts = Watts). The voltage and constant current is adjusted using potentiometers on the module.

I am using my module with a fan and resistors to produce a low wattage heater. I am using three 33 Ohm resistors in parallel and feeding them with 12 volts. The output is about 13 Watts and I am turning the 12 volts on and off with a thermostat (look for W1209 on eBay).

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I just recieved one of these from China

 

http://www.ebay.co.uk/itm/271859516859?_trksid=p2057872.m2749.l2649&var=570695506531&ssPageName=STRK%3AMEBIDX%3AIT

 

Very bright and very focused light, seems to be working great on a tall terrarium, i'm getting 6K LUX near the bottom of the terrarium (90cm tall).  My corn bulbs where only giving 500lux.

 

Early days but looks very interesting.

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I just recieved one of these from China

 

http://www.ebay.co.uk/itm/271859516859?_trksid=p2057872.m2749.l2649&var=570695506531&ssPageName=STRK%3AMEBIDX%3AIT

 

Very bright and very focused light, seems to be working great on a tall terrarium, i'm getting 6K LUX near the bottom of the terrarium (90cm tall).  My corn bulbs where only giving 500lux.

 

Early days but looks very interesting.

 

Very interesting, keep me updated on your future results!

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I have one of those on my small tank (2ft) driving an 18W LED - very handy little unit.

 

It's been running for over 12 months now.

Edited by Hud357
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I use a special floodlight. Christian Ritter of the G.F:P is selling these lamps. There are 2 Nicha CoB LED with 33 W each. It is only in use during the wintertime in my conservatory to give more light to the Cephalotus for a better color. Could be working if you mount the floodlight above a terrarium or aquarium.

23655182rz.jpg

 

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  • 4 months later...

Hi all,

Just thought i would post back so you know i'm still alive after tinkering.

The LEDs were a great sucess and i managed to keep a lot of my sundews growing over winter and even got some cuttings going which took to the light very well.

I eventually moved the LEDs to a large reflector i made up from a huge amazon box and a survival blanket. I upped the voltage so they are now running at 60W (20W each LED). This has allowed me to mount the light to the ceiling and the leds light up a larger area. To give an idea of the area I have roughly 50 plants under the light including some VFTs and sarracenia which are coming out of dormancy and starting to show their first leaves of the year.

So the plants are really liking it, and for roughly £60 which is what its cost to build i'm super happy. I already ordered some more for next year and i've got some 10W red blue LEDs to experiment with aswell.

Edited by MarkB
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  • 2 weeks later...

Hi all,

Just thought i would post back so you know i'm still alive after tinkering.

The LEDs were a great sucess and i managed to keep a lot of my sundews growing over winter and even got some cuttings going which took to the light very well.

I eventually moved the LEDs to a large reflector i made up from a huge amazon box and a survival blanket. I upped the voltage so they are now running at 60W (20W each LED). This has allowed me to mount the light to the ceiling and the leds light up a larger area. To give an idea of the area I have roughly 50 plants under the light including some VFTs and sarracenia which are coming out of dormancy and starting to show their first leaves of the year.

So the plants are really liking it, and for roughly £60 which is what its cost to build i'm super happy. I already ordered some more for next year and i've got some 10W red blue LEDs to experiment with aswell.

Nice to hear!

Same here, during this winter my tropicals plants have enjoined well, but using leds the  low heating was a problem to solve, hope this year..

Edited by Aidan
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I have to say that I'm winding down my LED's from 50->40->30 now. (3ft x 12 fish tank)

Interesting, were the neps still getting burnt or was there some other reason? I'm not familiar with neps but always wanted to try growing them.

I didnt end up using my tank in the end because i decided it was only going to be temporary over winter so i just have the plants sat on an old worktop in containers of sorts waiting for the weather to improve. I'm using a slightly bigger area roughly 5ft x 30 and i have the light fixed to the ceiling so quite a distance away from the plants which is why i upped the voltage. The plants seemed to love it but i've now swapped a lot round to the blue red 20W set up where they are not doing as well although the drosera appear more dewy.

I recently put some VFT under the white 60W and they came out of dormancy in a matter of just 2 weeks with traps fully formed now so i was quite amazed at that.

Some sarracenia i put under the white arent doing so well, brown spots on new growth but they were not in too good shape when i brought them in, brown spots on all the new growth but i think thats just due to them being so wet from being outside and nothing to do with the light. Hopefully they will pick up soon.

One problem i do have with the light is everything always wants to flower under it, i've already cut off a lot of flower stems which is where most of my cuttings have come from.

Edited by MarkB
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Had to take out a D. binata from the red blue light today its not looking well at all, started to droop over with no dew on the leaves so its back under the white light again.

Still i'm not giving up on the red blue light, i'm leaving the D. alicae, capensis, rotundfolia and a couple others that are under it to see if they adjust at all. I've added 4 more strips of red blue so 6 strips in total, running at 36W with 162 red individual LEDS and 54 blue. I suspect i could probably go higher with the power but the LEDs arent rated so i'm not going to chance it. Will just see what happens now with the increased light. The remaining Drosera are looking extremely dewy which could be a sign of not enough light but they are also more red looking so its difficult to say whats happening.

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  • 1 month later...

I cant explain why but the remaining plants took to the red blue light. All but the D. binata and capensis which i have moved in to the poly tunnel to recover but from my understanding those plants required the least amount of light.

The rest of the plants seem to be growing quite well and look healthy although i cant decide if they are more red looking or green so its very hard to judge.

IMG_20160514_184458_zpslertlcke.jpg

 

IMG_20160523_174433_zpsgvlhzhgh.jpg

 

IMG_20160523_174511_zpsmsjkp5ma.jpg

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I cant explain why but the remaining plants took to the red blue light. All but the D. binata and capensis which i have moved in to the poly tunnel to recover but from my understanding those plants required the least amount of light.

The rest of the plants seem to be growing quite well and look healthy although i cant decide if they are more red looking or green so its very hard to judge.

 

 

 

I've always had problems with sundews about the quantity/quality of  the light in my terrariums, I tried different setups but have never been as good as with sunlight, in addition each plant has its own exposition requirements which makes it very difficult to manage..

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