LED lighting over algae advice on the right driver.

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LED lighting over algae advice on the right driver.

Post  liquidg on 7th June 2012, 4:24 am

Hey guys, I need some tech advice.

I just finished the mini me NWMS and I am onto the lights.

The MR16 spot lamps I got are obviously 12 volt and on board I got them made with three cree 3 watt diodes,one xp-e blue and two xp-g cool white.

The algae area will have 8 spots over it so I need one driver and a spare if it breaks down to run them all at the right amount (to just under) of grunt to achieve their best out put but not over load them.

240 volt in and their energy out, nothing else.

I am building a computer fan into the fitting i am making and each spot is seriously vented so any heat issues wonít exist!

What do you think I need to run these? cheers Very Happy





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Re: LED lighting over algae advice on the right driver.

Post  finfan on 7th June 2012, 5:28 am

HiYa Liquidg

What you have is a MR16 (this is the type of fitting) 3x3W CREE Led globe, they require 12v DC and you could go to any electrical wholesaler and ask for the appropriate driver / transformer (depending on who you talk too) - this is option 1 -

Option 2 - If you want to get a driver to connect all from a single source then you really need to understand OHMs law and fundamental electronics - or you will fry them ! You will need to work out the drivers requirements, method they are connected internally (typically parrallel) and then the types of drivers available, were to get them, how to wire them and be very careful as the forward voltage these start to create across such a circuit can be dangerous (ask sottfromwello) .... Neutral

Here is a basic run down - really option 1 would be my recomendation


LED's are quite different to light bulbs. Light bulbs are designed to work on a voltage, LED's can work on almost any sensible DC voltage if you have a correct value resistor fitted.

Resistors are relativley inexpensive and basically restricts the current passing throught the LED, as the LED's has no current limit itself. If you put an LED on a battery with no resistor it would be extremly bright for a fraction of a second before it blows.

To connect LED's into a circuit, it is advisable to know a little about Ohm's Law, a few basic formuals is all thats needed.

The figures you need to calculate the formula is the voltage you wish to work from, the current you wish to pass through the LED, and the forward voltage of the LED. The forward voltage can be found in the data sheet for that particular LED, it is the value of Vf, around 3.4V for White, different colours have different values.

Ohms law formula is V = I * R.

As we wish to calculate resistance it can be arranged to say R = V / I.

Connecting one LED and one resistor
For example lets say we have a 12V supply, and wish to run one Blue LED. We know the forward voltage Vf is 3.4V, and we wish to pass 20mA (0.020Amps) through the LED.



R = (12 - 3.4) / 0.020

R = 430 ohm resistor.

Connecting two LED and one resistor
As we have plenty of volts to drop accros the resistor we could add another LED in the circuit which would make the circuit more efficient. At the moment the resistor will get warm depending on power dissapation of that resistor, the reason for heat is that you are converting energy to heat which is wasted power. By using two LED's there re less volts to loose accros the resistor, it will still be the same current as passing throught one LED, in effect you are getting extra light as its two LED's, and less heat being generated.



R = (12 - 3.4 - 3.4) / 0.020

R = 260 ohm resistor.

Calculating resistor power
Power is measured in Watts, things like light bulbs are measure in Watts, most of the power is heat as a light bulbs is effectivly a resistor.

It is possible to calculate the power rating of the resistor required.

P = (V drop) * I

For one LED and one resistor at 12V

P = 0.172 watts

For two LEDs and one resistor at 12V

P = 0.104 watts.

Most of the time the rating of the resistor dosn't matter as they are usually 0.5watts which is plenty, but if you were to use surface mount resistor you would need to be aware.

Connecting LEDs in series and parallel

The above methods of connecting LED's was in series, if you wished to have many more LED's in the circuit you can basically multiply up the circuit across your power source to have as many LED's as you desire, this is where you may need to take care of the resistor heat, if you have many LED's in a small box with the resistors, all of it could get a little warm.

Clear as mud ah !
Cool



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Re: LED lighting over algae advice on the right driver.

Post  liquidg on 7th June 2012, 12:04 pm

What the??? Shocked Shocked
Mate you know my expertise is not in tech,I have looked at ideal lighting for these but not cutters as yet,just a simple answer,to run all spots off one driver,what one should I get,you know the size or brand? affraid

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Re: LED lighting over algae advice on the right driver.

Post  finfan on 7th June 2012, 4:33 pm

Ok - so collectively you have 24 LEDs to run so this is the type of thing to look for -

Inventronics drivers are some of the best in the industry for lighting LEDs

These drivers can handle LEDs without any additional power source. No need to buy anything extra, LEDs can be wired directly into the driver similar to meanwells.

The 75w versions have several key feature including:

Total Power: 75 Watts

Active Power Factor Correction

IP67 Compliant

Lightning Protection

Dimmable

Don't forget to pickup a AC plug (USA/Canada) for your drivers

This driver is perfect for running up to 31 CREE XP-G/E LEDs on one driver, no parallel strings needed

WARNING: This is a very high voltage driver. Any exposed contact points can cause serious injury or even death. Please do not purchase this driver if you are not sealing your fixture and do not now how to do stray voltage checks. LEDGroupBuy.com takes no responsibility for the misuse of this driver.

Other Details Brand: Inventronics Weight: 28.40 Ounces Wattage: 75W Max output voltage: 54-108v Input voltage range: 90 - 305 VAC, 47 to 63 Hz Input current: 0.7 A @ 110 VAC, 0.35 A @ 220 VAC Inrush current: 50A at 230VAC 25ļC Cold Start Dimmable: 0-10v Dimming range: 10-100% Spec: EUC-75SxxxDT LEDs: 16-31 XM/XP LEDs in series at 700mA

And it will cost about $76 plus postage...there are many brands etc but look for the above specs....there really is no just plug n play for this as the requirements vary so much....


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Re: LED lighting over algae advice on the right driver.

Post  liquidg on 8th June 2012, 2:31 am

Now thatís a little better,lol,thanks. cheers

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