I have very limited knowledge about electronics, but a very good idea
I want to control 200W of RGB-LEDs with my Arduino Duemilanove, both dimming and color. What is the best solution to reach the required power?
My thoughts goes like this. I use three PWM-pins to controll each color in strength, and could in that way create any color in brightness 0-100%...
Is it possible to just add an amplifier between the board and the LEDs? Or is it not possible to amplify the PWM-output?
Depending on the led's you are going to use and the powersource, this is a feasible project.
I think it is best to use FET's.
Using leds in series you can limit the current use of your powersource and skip the need to use resistors and such.
If you share more details about the project, i and others can provide you with better answers.
You should only use a resistor to limit the current if the current in the LED is about 40mA or less. If a LED takes more than this then you need a constant current driver for each LED or series string of LEDs. As RGB LEDs are often common anode or common cathode you can't put these in a series string. Only if you have access to both cathode and anode can you put them in series.
Ok. I will try to explain a little more about my project.
I want to control both color and brightness of 20 RGB LED-strips. Each strip contains 45 RGB LEDs, in total 20 strips times 45 LEDs = 900 LEDs. Each strip is rated 9.8W, in total 196W.
I´m using the Duemilanove board and has so far connected three seperate LEDs, one red, one green, and one blue, to three PWM pins set for output, just to learn.
I´m assuming that it will be possible to use the board with some kind of amplifier to drive the strips... but I don´t know how. Is it possible? To amplify the PWM-output?
The strips should be driven by 12VDC, 16,3A?? I´m really at the bounds of my skills here.
Next step in the plan will be to send, via wifi, input data from a Iphone-app to the Arduino, regarding brightness and color.
Thinking a little bit more. Is it a RGB LED driver i need? And in that case, I assume there is a way to hook up the Arduino with the driver...
When I read about PWM-dimmers I can see that they are supposed to be connected after the driver... can I input a PWM current into the Driver?
I'm building an RGBW LED floodlight.. which in function is really the same thing as your design.
What we need to know is the type of LED strip and it's wiring. What you want is is each color to be an isolated circuit, with the LED's strung together in series and both the positive and negative connections available. Your current supply circuit feeds the LED's positive and your PWM transistor acts as a switch between ground and the LED strip. Given that number of LED's and the currents/voltages, you'll probably break it down across several supply/sink setups to keep it reasonable.
Actually... I think this is a lot easier than you think.
I'm pretty sure your LED strips already have resistors in place. You don't actually need to amplify the PWM signal at all, you just need a component on each PWM output capable of switching a much larger source.
You're just going to need a transistor (there are many many articles about these) and a 12v supply capable of putting out 200w.
Ohms law says 200w @ 12v is 16.67 amps... maybe there is a better way to do it though. I think this is a start!
I'd say start with 1 strip of LEDs and then graduate up to the larger project
You don't put amps through an arduino, you power it with a voltage and it takes the amount of current it needs (amps).
If you feed a voltage into the Vin pin then the most you can take out of the +5V pin is about 650mA (depending on the actual voltage on Vin). This is due to the power dissipation on the internal regulator.
If your strips are common anode (the vast majority are), products like this are easy and fast ways to do what you want. YES, you can absolutely do the same thing with power MOSFETs, and I have. This is just the type of device I personally go to when I want to do it all quickly.
A google search for RGB LED amplifier will show you thousands of alternatives.
Seller Ray Wu on aliexpress.com sells inexpensive units that are good quality.
..the power mosfets have usualy a large gate capacitance, so you might need a "driver". The driver has to be put between arduino's pwm output and the mosfet's gate.
When not using the driver, the mosfets will be operating in a "linear region" (because the arduino's low output current will charge/discharge the mosfet's gate capacitance rather slowly when switching between logical 1 and 0) and the mosfets might become quite hot. The power dissipation of the mosfets is proportional to on/off switching time (influenced mainly by the gate charge/discharge speed) and the U*I between mosfet's source and drain.
P.
hi
Im not understand what you really want, but if you dont have an Electronic knowloge I recomend you to use power supply whit PWM included.
The image are in spanish but you can deduced
I can you you more option but I need to undertan better your proyect if you draw you led configuration maybe ease to help you.
you can use the IC ULN2003 to drive a led dependig how many milli amp consume.
Connected one 9.8W strip directly to the Arduino (connected to 12VDC) tonight. Green and Blue are responding as they should, red is static.... why is that? Why isn´t the PWM-signal sufficient for the red, but for the blue and green? Guess I need that MOSFET, could you please give more specific details about what to buy... https://www.elfa.se/elfa3~se_sv/elfa/init.do?item=71-147-17&toc=19199??