# Forum Home Renovation Lighting  LED driver compatibility

## jules21

i've bought some 12V LED garden lights that sum to about 180W. i understand that i need an LED driver, but other than providing suitable current at the correct voltage, does the driver need to be compatible with the brand/type of LED light?  
i'm looking at this driver, which is a lot cheaper than the ones of the same brand as the lights i'm buying (although i am planning on using two different types of LED lights), which don't even offer a product with sufficient power (so i'd need to buy 2). 
does this matter? is an LED driver just a commodity or do they have to be specially matched to the brand of light hooked up to it? i'm assuming it's the former but confirmation would be appreciated..

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## Moondog55

The LED driver is usually part of the lighting assembly and connected directly to each individual LED, you may be confusing the driver with the power source, have you tried a battery charger? or for a trial just a fully charged car battery??
Are these LED lights already cabled up or did you buy naked components??
Good 12V outdoor rated trannies can cost quite a bit
pictures would help

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## jules21

the LED lights i'm planning to use are this one and this one. 
the info for the first one (only) says "Must be used with a suitable LED Driver (HV9651-HV9655)". the other one doesn't specify that.

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## bigGayAl

An LED "driver" as described here is just a 12V power supply. Any power supply will do as long as it can supply enough power for all your LED lamps. Obviously, it must be rated for outdoor use if it will be installed outside. The only potential problem is that some power supplies are not well regulated. Even though they are labelled "12V" they will put out 16V or 18V under light load and will drop to around 12V only when loaded. A higher than specified voltage will burn out, or at least shorten the life of LED's. 
I would think that any power supply made for powering LED's should be fine. If you want to use any other power supply or battery, you should check it with a voltmeter. 
I think the comment "Must be used with a suitable LED Driver"  means, "Don't forget to also buy a power supply".

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## applied

Led globes are a very sensitive to voltage and polarity please don't listen to people saying just hook it up to any old junker transformer you have.
The secret to led lighting is in the layout design you should post the exact specifics of what your trying to achieve eg. How many lights your installing the locations eg on wall or in a deck or whatever the distances between and anything else you can give us and it will make your life much easier.  
You will most likely find one large transformer is not your best or most cost effective solution you could use a mix of transformers to get better results the Enemy of theses lights is voltage drop if you plan to use one large transformer then you also need larger cable and more of it but if you can brake it down into strings or individual lights you can use smaller transformers but more of them or one large one centrally located really depends on the job. 
Another thing to consider is the lights are ip65 therefore you won't need outdoor transformers if they are in the fittings.
That second can type usually has a round wound or electronic transformer that fits snug and can handle heat you may struggle to find replacements suitable to go inside them so a string approach is best.

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## ringtail

180 watts, wow, thats a crap load of LED's

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## applied

> 180 watts, wow, thats a crap load of LED's

  Yeah about 15 to 20 that would just about light up an elevator or dog house nicely

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## Moondog55

LED Drivers  http://lightingmatters.com.au/cart/i...694f9a1a51518f  10 watt LED Driver MP-3360 - Lighting Matters    with this unit you still need a voltage source such as a toroidal trannie or car battery charger
So with LED lighting the "Driver" and the "Power supply" are often separated. As applied says they are very sensitive to voltage fluctuation and jitter

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## ringtail

I wasn't been sacarstic in case anyone thought I was. I just saw the lights had 9 leds @ 1 watt each

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## bigGayAl

LED's are not sensitive to voltage fluctuations and jitter. One common way to drive LED's is to pulse them with a square waveform to reduce power consumption. 
The only thing you have to worry about is not exceeding the maximum forward current. This can happen if your power supply voltage is too high (you can test this easily with a voltmeter) or from voltage spikes. Voltage spikes come from your mains and your power supply should have some sort of filtering. Unfortunately, no filter can block very high voltage spikes, such as from a nearby lightning strike, and it is impossible to determine if your spike filter is actually doing anything at all. 
The LED "drivers" advertised seem to be just voltage regulators. I really dont see the advantage of having multiple voltage regulators in a circuit except to increase the price of the installation. If you just use one voltage regulator built into you power supply, you just run the risk that voltage drops in your wiring will result in slightly dimmer light in your garden. 
By the way, an LED driver is actually a circuit that supplies the required current to each individual LED within the LED lamp. This can be a constant current source, a pulsed current source or, most likely, a simple current limiting resistor. 
I am amazed that they sell toroidal transformers to power LED garden lights. Toroidal transformers have several important advantages over traditional laminated power transformers. None of these have any relevance to powering LED lamps. 
LED's have been around since the 1960's but now that they are being sold directly to the consumer, the marketing guys are moving in. It won't be long before they are telling you to buy LED certified, oxygen free copper wire at $20 a meter.

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## applied

> I wasn't been sacarstic in case anyone thought I was. I just saw the lights had 9 leds @ 1 watt each

  No we knew I was being sarcastic because LED lighting although I have it is rubbish for task lighting well lighting in general really.

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## cherub65

> No we knew I was being sarcastic because LED lighting although I have it is rubbish for task lighting well lighting in general really.

  You can get quality if your prepared to pay for it, they use LED in ambulance interiors now which are rated to give off as much light at midday.
Know a guy who builds ambos for many states of Australia and they use them here  8 Inch Round Super-LED Ambulance Interior Light - RadiosNLights.com

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## Moondog55

Toroidals are simply more available and weatherproofable; if you want a cheap voltage source then you could just use an old computer power supply and keep it out of the weather.
My understanding is//was that the driver was the constant current circuit used with each LED or group of LEDs. It can be as simple as a suitable resistor and associated heatsink
Checking the Phillips-Luminaire site it seems that LEDs are very sensitive to voltage fluctuation and jitter "insofar" as this increases the heat produced by excess forward current and excess heat shortens the working life, sometimes dramatically.
A good LED globe has all of these built-in; which probably explains the high cost of some units ( not to mention excess profits on a "NEW" technology )

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## president_ltd

> Toroidals are simply more available and weatherproofable; if you want a cheap voltage source then you could just use an old computer power supply and keep it out of the weather.

  never use an old PC PSU 12V rail lightly-loaded if you expect that 12V rail to be anywhere NEAR 12V....

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## applied

> Toroidals are simply more available and weatherproofable; if you want a cheap voltage source then you could just use an old computer power supply and keep it out of the weather

  Or buy a proper led transformer off eBay for $5 delivered  I use them often and haven't had one fail yet.

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## mattski2008

Dont use a 12V AC power supply, use a 12V DC power supply.Led's consume D.C to produce light and are generally meant to be operated on D.C. but  they will operate on A.C. However with A.C. of equal voltage the value of the current limiting resistor will have to be adjusted to achieve the same brightness. This is because with A.C. the led will only be lit when the current flow is in the proper direction. When the current flow reverses the led blocks current flow and remains unlit. Thus A.C. applied to an led will cause it to blink on and off even though at high enough frequencies it will appear to be lit continuously. To make a blinking led appear as bright as constantly lit led the current limiting resistor's value is lowered to allow more current flow causing the led to be brighter when lit. This causes a greater average light output and thus a brighter appearing led. In my experience LEDs powered by DC will last a lot longer.

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## Moondog55

Here am I thinking that computer power supply were AC -> DC converted, unlike toroidals which are simply voltage converters and need a second; stage rectifiers, and perhaps even smoothing caps

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## bigGayAl

A computer power supply would not be a good choice as it is a complex piece of equipment supplying a bunch of different voltages required by a computer. If you accidentally connect the -12V instead of the 12V you will damage the LED's. 
A 12V AC power supply would not work as a reverse voltage of 5V or 6V will damage the LED. 
All you need is: 
1. A transformer to convert 240V AC to a lower AC voltage. Toroidal or laminated core. Makes no difference except that toroidal is more expensive.
2. Recifier circuit to convert AC to DC.
3. Voltage regulator to convert whatever DC voltage we have to 12V. 
Most power supplies or plug-packs labelled "DC 12V" will have all three built in.
I think a battery charger for 12V batteries will produce considerably more than 12V.
To make sure a power supply is regulated, check with a simple $10 voltmeter that the output is about 12V. Doesn't have to be very accurate. Probably anything from 10V to 14V will be OK.

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## mattski2008

> A computer power supply would not be a good choice as it is a complex piece of equipment supplying a bunch of different voltages required by a computer. If you accidentally connect the -12V instead of the 12V you will damage the LED's. 
> A 12V AC power supply would not work as a reverse voltage of 5V or 6V will damage the LED.

  A computer power supply only produces one voltage. That is the voltage required for the computer to work.
An AC power supply will work as stated in my previous post. Most LED fittings I have seen are using a 12V AC power supply. Where a 12 dichroic has simply been replaced with a LED.

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## bigGayAl

> A computer power supply only produces one voltage. That is the voltage required for the computer to work.

  A desktop computer power supply generates the following voltages 12V, 5V, 5VSB, 3V3, -5V, and -12V. Lookup "Power Supply Unit" in wikipedia 
As for running an LED from AC, it is not possible for a naked LED but I decided to look inside my garden light and it has a diode in parallel with the LED's. This protects against the light being connected the wrong way around and will prevent damage if powered from an AC source.

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