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I've a Street light consists of 1000 LEDs 1watt each LED and have external power source to power them
i want to control these 1000 LEDs from Arduino just ON/OFF and may be dimming in the future.
a friend told me that i'll need a driver circuit or put LEDs on groups 100-200 LEDs per group.
i hope i can find help here on how to power these LEDs 1000 watt load


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Usually with that many LED's you would use a matrix display where each row is lit in turn.  The problem with this is that if you have 16 rows (and 64 columns) each row can only be lit 1/16th of the time, limiting brightness.  If you want maximum brightness you will need a fixed current power supply and a transistor switch for EACH of the 1000 LEDs.  This can run into a lot of money.
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You can minimise the control needed by putting LEDs in seriese if you have enough voltage to play with.
How is the light wired up, all the LEDs are not unwired are they?
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the LEDs are parallel connected each row with power supply, and i don't want to control each LED .
i'm using this matrix like a flash light, so i just want to switch all the LEDs ON/OFF
the problem with me is how to drive such power 1000 watt from arduino
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the LEDs are parallel connected each row with power supply
I bet they are not. You can't connect LEDs in parallel just straight.
We need to know the voltage and current it requires to drive it.
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i'm using this matrix like a flash light, so i just want to switch all the LEDs ON/OFF
the problem with me is how to drive such power 1000 watt from arduino

That will be easy!  A MOSFET that can switch 1000W will only cost about $20.  You will need a 10V (or higher) supply to switch it properly.  You will probably also need a good heat sink.

A relay (contacts 100VDC 10A) might also do the trick if you want to give up your dream of dimming.
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One kilowatt of LED's?  Number one... WANT WANT WANT!

I'm using a hundred watts as a photography flash!  Typically the return rate is around 30-50 lumens per watt using the cool white LED's, so you are talking about 30-50k lumens, or more.  That's a LOT of light, in fact, it's quite a bit more than a typical Metal Halide street light.  Sounds like some kind of runway lighting or something.  For reference, a typical High Pressure Sodium Arc lamp (pretty much the most efficient form of lighting that is commercially used, it's what the orange-pinkish street lights typically are) at 400 watts puts out around 30K lumens, and a metal halide (which are white and not the "orange" of sodium lights) arc lamp will get you around 60,000 lumens at a Kilowatt-- that's arena and stadium lighting.  Where did you get this thing, and  What in God's name are you going to light up with this monster?  I am really interested in the scale of this, and want to know the specs... I am suspecting that it's going to be delivering the power to the array at a pretty high voltage (LED's in series) to keep the current reasonable.  Assuming it feeds the array with a maximum of US standard house current levels, that's 120v, One watt LED's typically want 3.3v ish at around 330mA.  If that's the case, it's probably 30 LED's in series in each row, with 33 or possibly 34 rows, each drawing 330mA.  That's about 11.5A @ 120v with a little overhead.  No small amount of power.  Be careful, I suspect the supply voltage is high enough to kill, take care to insulate connections and handle it as if you were handling house current, as the voltages are as high (or higher) in all likelihood!

If you aren't interested in controlling the LED's individually, just use a small bipolar transistor to switch a power MOSFET.  To make it simple, I'd probably use TIP120 or some other Darlington NPN and just switch 12v to the gate of the MOSFET.  It's a bit less efficient than some like to see, but I feed my Arduinos 12v and let the 7805 on the Arduino drop it to 5v for the chip... but it leaves me with 12v at the Vin pin, which is a useful voltage for external devices.  As for the MOSFET, You'd probably want to add a large value resistor (100k?) between the gate and ground, to discharge the gate capacitance when switching "off".

Really, if you already have a power supply which can operate the panel, all you really need is a switching transistor that can handle that level of power.  What's the current and voltage requirements of the beast, maybe we can help you shop out a proper switching transistor/setup.
« Last Edit: June 02, 2012, 08:03:40 pm by focalist » Logged

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That will be easy!  A MOSFET that can switch 1000W will only cost about $20.  You will need a 10V (or higher) supply to switch it properly.  You will probably also need a good heat sink.

A relay (contacts 100VDC 10A) might also do the trick if you want to give up your dream of dimming.


What MOSFET type should i use and do you have simple design for building this circuit

someone told me that i can use a relay on the ground of LEDs and let the LEDs get the +ve power from power source, is this a good idea?

Thanks
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If you aren't interested in controlling the LED's individually, just use a small bipolar transistor to switch a power MOSFET.  To make it simple, I'd probably use TIP120 or some other Darlington NPN and just switch 12v to the gate of the MOSFET.  It's a bit less efficient than some like to see, but I feed my Arduinos 12v and let the 7805 on the Arduino drop it to 5v for the chip... but it leaves me with 12v at the Vin pin, which is a useful voltage for external devices.  As for the MOSFET, You'd probably want to add a large value resistor (100k?) between the gate and ground, to discharge the gate capacitance when switching "off".

Really, if you already have a power supply which can operate the panel, all you really need is a switching transistor that can handle that level of power.  What's the current and voltage requirements of the beast, maybe we can help you shop out a proper switching transistor/setup.
i think it will be a part of a highway billboard

till now i don't have much details about this panel coz there is another team are building it, i'm only responsible on lighting ON/OFF this thing from Arduino and other functions

i've 1000 watt LEDs load powered by 5*200 watt power supply. i'll give you all the specs details later when i get it

Do you have any suggestion design for building this circuit?
someone told me that i can use a relay on the ground of LEDs and let the LEDs get the +ve power from power source, is this a good idea?

Thanks
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Do you have any suggestion design for building this circuit?
someone told me that i can use a relay on the ground of LEDs and let the LEDs get the +ve power from power source, is this a good idea?
No it is not.
Power LEDs need a constant current supply, unless you know how they are wired you can't begin to design the circuit. Unless it is wired correctly you are looking at one constant current supply per LED.
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Highway billboard?  Like aimed AT traffic at night?  I see a problem here-- 50k lumens at narrow angle blasting at drivers.. are you SURE these guys have any idea what they are doing at all?

You need to find out how they are wiring this, because you cannot design the switching and arduino side without them providing rhe specifications.

Seriously though-- especially because many LED's are quite directional, this could actually be dangerous....
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perhaps someone can comment on this circuit board for a 500-led (5mm) light panel (that's apparently a knock-off of a more established brand). Initially I just connected a PWM to one of the potentiometre's legs to control fading, until the unit stopped responding so I pulled it apart and tried to rewire it with my own components.

Notice the following: there are no transistors/mosfets/heatsinks on the board. the potentiometre controls brightness to all led's (but not to complete off), and there are four switches to control every fourth line of led. it is an incredibly bright panel (running at 12 volts up to 5 amps).

It gets incredibly hot when using the same power supply I have been unable to run it reliably using even one mosfet per 50 led's. ceramic resistors are out of the question.

So I really want to know what part of the circuitry makes it run so cool even when fading? there are no resistors mounted with the led's and they are in series for the most part. (circuit attached)


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