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hello everyone im new smiley-mr-green , been checking out the arduino for a couple  weeks and i would like to start a project. i got me 3 strips of leds lights and i was thinking to plug them into different timers that i was going to purchase at the local hardware store but the arduino project seems more fun and i can make more out of it in the future..... so here is my project 3 led strips, 2 running 9.1w at 24v and the 3rd running 10w 12v. i was wondering if i can put all 3 strips on one of the boards???? if so can i run them with different voltage and timers??? that being said how do i go about choosing a board? also i want to add buttons in case i want to override the preset timers...
if all this is possible which i think it is for what ive been reading i know it would be alot of work  smiley-eek-blue but im up for the task.

thanks
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Welcome to the forum.

You can use an Arduino to control transistors to control power to the strips.
Connect the +of the LED strips to your positive supplies.
Connect the - to Logic Level N-Channel MOSFETs.
Drive the Gates from the Arduino, the MOSFETs will connect the - of the LED strips to the Ground of the supplies.
Connect all the grounds together.
Uno will do fine, lots of pins available for buttons.


* Controlling_LEDstrips.jpg (45.57 KB, 960x720 - viewed 72 times.)
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Thanks for the replay CrossRoads it looks so simple in that diagram I'm going to order the UNO and c where I stand. In the diagram I c some resistor in each line going to the led strip it's been so long since I did a project like this I want to know how can I calculate what resistors I will need for each line ?? Or will that be the MOSFET in each line  ???

Thanks
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Resistor will be small, like 180 ohm.
Just prevents too big of an inrush of current into the MOSFET's gate capacitance.
Say the cap was a dead short to ground - you want to limit the arduino's output current to say 30mA.
V=IR, or V/I = R
5Voutput/30mA = R = 167 ohn, so 180 will do nicely.

I'm assuming your LED strips have current limit resistors built in, so I didn't add any to the diagram.
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Hello CrossRoads I'm back, been doing a lot of reading, got the arduino UNO and been looking for the resistors but apparently these are hard to find.... Anyways Got a few questions I can't find any info on how the MOSFET will convert the voltage from 5 to 12 and 24v??? Will i need a mosfet driver or will the arduino do it?? Which mosfet will I use for the 24v led strips and which one will I use for the 12v strip??? Also u gave an example of 30mA going out of the arduino, I believe to find the amperage of the light Is the wattage divided by the voltage right?? In that example why 30mA??, where does that figure comes from? Is that for the MOSFET or the lights?? Maybe that depends on the type of MOSFET to be used if it is for this??
I'm sorry for the ignorance but it hasrelly been long time since I did something like this.
And trully never worked with MOSFETS And thank you for the help
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180 ohm resistors are hard to find? Where are you looking?

The MOSFET does not convert any voltage - it merely turns on and connects the LED cathode to Gnd. The LED anodes are at +12 already, so closing the loop electrically lets the LED strip turn on.

MOSFETs are voltage driven devices - a Logic Level N-channel MOSFET needs ~4.5V to turn on fully. The Gate has some capacitance associated with it - we use the 30mA out of the Arduino to charge that capacitor up quickly (and discharge) so the MOSFET turns full on & full off quickly.
The cap looks like a short to ground when discharged - the 180 merely limits the current that charges the cap.
5V/30mA =  167 ohm; 180 is a standard value.

A N-channel MOSFET, Logic Level, Low Rds, fairly low gate capacitance, thru-hole, part like this would work well
http://www.digikey.com/product-detail/en/NTD5867NL-1G/NTD5867NL-1GOS-ND/2401422
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Hey crossroads it's me again I should have xplained better myself I was looking in some local stores but they didn't have the resistors for 180ohms but I finally found them 180ohms 1/2 watt, the MOSFETS I could not find in the stores they had some IRF*** some numbers but all were 100v or more not too sure if I can use those if not... Not big deal I saw the one u posted a link to and would go with those... All it's left for me to get is the MOSFETS so I'll order them online and start working on it thanks for the help
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the MOSFETS I could not find in the stores they had some IRF*** some numbers but all were 100v or more not too sure if I can use those if not...
The 100V rating is not a problem.  That's the maximum Drain-Source (output) voltage you can apply without risking damage.     

CrossRoads mentioned "Logic Level MOSFETS".    That relates to the Gate-Source (input) voltage.   Most MOSFETs require more than 5V at the gate to "turn on".  A logic-level MOSFET can be turned-on with the 5V signal out of the Arduino.


So for example, with a logic-level MOSFET you could use the 5V output from the Arduino to control 100V.   (But that would be getting a bit dangerous for the human... smiley-wink )

P.S.
Just a suggestion...  I'd "start small".   I assume you've already played around with resistors & LEDs connected directly to your Arduino.   Next, I'd try one regular-little LED with one MOSFET at 12 or 24V (with the appropriate current-limiting resistor on the LED).  Then replace the LED with the higher-power LED strip.   Once you know your basic design is working, you can build the other "channels".

You might just want to leave regular LEDs on the Arduino outputs along with the MOSFETS, at least during development, to help with troubleshooting & debugging in case something goes wrong. 
« Last Edit: October 10, 2012, 04:03:19 pm by DVDdoug » Logged

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they didn't have the resistors for 180ohms but I finally found them 180ohms 1/2 watt,

You don't have to have those resistors.

Quote
the MOSFETS I could not find in the stores they had some IRF***

Whether those mosfets work will depend on what led stripes you have. If those are rated at different voltages and have no means of self-regulating the current, hanging them to the highest voltage will surely burn them instantaneously.

If you are switching indeed 1amp or so, something like IRF540 (a dime a dozen) would handle, even at 5v.

I would spend more time understanding the led stripes before doing anything.
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You don't have to have those resistors.


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the MOSFETS I could not find in the stores they had some IRF***

Whether those mosfets work will depend on what led stripes you have. If those are rated at different voltages and have no means of self-regulating the current, hanging them to the highest voltage will surely burn them instantaneously.

If you are switching indeed 1amp or so, something like IRF540 (a dime a dozen) would handle, even at 5v.

I would spend more time understanding the led stripes before doing anything.

the led strips do have resistors some lights are 223, 410 and some are 270 i think its very hard to read the numbers off them im gonna try to include a pic if it allows me and also i am including a link to the strips webpage.
http://www.current-usa.com/aquarium-led-lights/truelumen-pro-led-striplights
Sorry I forgot to say the strips I'm using are 3002 and 3003


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« Last Edit: October 11, 2012, 07:17:21 pm by Sarces » Logged

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270 = 27 Ohms  (not 210)
470 = 47 Ohms
223 = 22K Ohms
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hello... so i went back and got a irfz24n mosfet got everything together (im including a pic) and most of it is working w/o a problem 1 little detail is im not able to make the strip turn off completely ive been playing with different basic programs but to no luck as to turn the strip completely off, ive also tried different connections the strip does dim a lot more if i connect the source to led - instead of drain to -....... maybe someone can tell me if im connecting anything wrong ???

thanks for all the help


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maybe someone can tell me if im connecting anything wrong ???

You do not need an arduino to try this:

1) power -> led's anode -> led's cathode -> drain;
2) source -> ground;

now, connect gate to power, the leds should light up; then connect gate to ground, the leds should be completely off.
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maybe someone can tell me if im connecting anything wrong ???

You do not need an arduino to try this:

1) power -> led's anode -> led's cathode -> drain;
2) source -> ground;

now, connect gate to power, the leds should light up; then connect gate to ground, the leds should be completely off.


everything works fine if the arduino uno is not there
update;
now i have pluged the arduino GND into the source and thr led strip does what is suppose to do. dont quite inderstand why... thanks for all the help now into the fun part programming would come back if i have any questions
Thank you very much to CrossRoads and everyone else that helped
« Last Edit: October 14, 2012, 11:09:00 pm by Sarces » Logged

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There might be some residual current leaking from the led pin on the arduino depending on how you have the pin set up in code.

Make sure you have
Code:
pinMode(ledpin,OUTPUT); //7 8 9 in the example circuit.
in your setup function - change out ledpin with whatever your pins are, you could even just use the numbers.

Also, likewise you may need a pulldown resistor from the pin directly to ground to make sure the capacitor in the mosfet doesn't cause you any trouble.  Try adding a 10k resistor from each led output pin directly to ground.  This higher value resistor will make sure the output truly sees 0v ground, but when the pin turns on, the 5v will easily overpower that resistor and go to the mosfet gate.
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