RGB LEDs

Hello everyone,

I'm new to the Arduino community but can't wait until maybe some day I can help others out.

So I just purchased an Arduino and with my project I need to light a bunch of LEDs up. Actually they will be RGB LEDs and I made a controller to adjust the colors of them. The idea is to hopefully be able to light around 65 LEDs.

Being new to this stuff and eager to learn, what would be the best way to setup the LEDs so they are controlled by the pots?

Thanks for any help,

First question is how many potentiometers will you have, and how many LEDs is each one to control?

You might have noticed that the Arduino failed to come with 65 input and 195 output pins…

Thanks PaulS,

I did notice that. My plan is to run them all slaved to eachother. Basically I'm trying to make a big ring with the same color. I have three potentiometers, (1 R, 1 G, 1 B).

I want them all to be consistent with the color so I wasn't sure if I could control them all from from pins 9, 10, and 11 as PWM.

Ultimately, I want the LEDs to light up when movement is detected. The pots are just for changing colors of the LEDs depending on what mood myself or my fiance are in that day.

Would it be best to run the power of the LEDs off a wall wart then just colors from the arduino? Would that be possible?

Thanks again,

You can do it with a (BIIIIG) wall wart and some extra components between the 3 Arduino PWM pins and the LEDs but 65 RGB leds will be a nightmare to wire up and they will draw a lot of current.

It might be a lot easier to use one or two metres of these:

http://www.dealextreme.com/details.dx/sku.14965

probably cheaper too.

They are very easy to drive with just 3 transistors or a single ULN2003 darlington array IC, and a reasonable wall wart.

The LED strip might not be quite as bright as "real" RGB LED's but i used a 1 meter strip in a mood light type of lamp and despite being behind opalized glass they give a nice light.

Thank you MikeMo,

This does look like something I'm looking for. I guess I was wanting to just make something myself but this might be the better alternative. I have a DVD rack that has 16 cubes in it that are 12" wide. My goal was to set LEDs in them to project light onto the DVDs when we're near them.

I just wish I could find decent(ly) priced RGB LED light strips to fit these dimensions and allow me to control them with an arduino.

This is my first arduino project so I just wanted to make it awesome, but maybe I should just limit it for now.

The link you gave would have been perfect if it fit the 30cm/12in dimensions.

Thanks for all the help, :)

The link you gave would have been perfect if it fit the 30cm/12in dimensions.

According to one of the reviewers, it can be cut into pieces, so if you go this way, you should be able to fit into your DVD rack.

HTH
GB

Yes they can be cut into sections with 3 LEDs approx 10 cm / 4 " each

But solddering wires to these sections is a challenge :-)

What about using something like a TIP31 Transistor which will handle a couple of amps each. Each TIP31 can be driven by a higher current and voltage giving you more grunt than the poor old Arduino can deliver. Adding something like a TLC5940 as well would give you 16 channels PWM. This is something I'm looking at trying myself later on.

http://www.arduino.cc/playground/Learning/TLC5940

Forgot to add this link http://led.linear1.org/led.wiz Its a LED Matrix calculator you might find useful in planning current limiting resistors etc.

You could wire them up with the colors on the pwm ports and then have sections of like 5 leds or so with the grounds hooked up to a transistor and that to a pin and ground so you can flash the different sections of the rope and not be powering the eintire thing at once and also just set the pwm using the fade function and have it be set to a single pot so it will fade the colors with one knob and also with this setup you can give the thing patterns and other stuff like that (if you want i can draw schematics for you)

As for the movement you can grab a PIR (passive infrared reciever) to detect heat and movement from people walking around, you can probabally point it at the ground so when it sees your feet up close it will activate the tower

Also to get leds for dirt cheap ( like the rgb ones) check out sure electronics, its a chinese company that. Think is a manufacturer so i buy rgb leds in packs of 100 for about $20 and shipping is steep but if you buy a few packs it is worth it

What about using something like a TIP31 Transistor which will handle a couple of amps each. Each TIP31 can be driven by a higher current and voltage giving you more grunt than the poor old Arduino can deliver.

Well its not quite got the current gain needed (only 25) to work at full current. Also it has a high saturation voltage of 1.2V so it will need heatsinking (the TIP31 is designed for audio output stages I think, not switching)

A Darlington power transistor would solve the lack of gain (though have a slightly higher saturation voltage). A power MOSFET can do better if you want to drive several amps from the Arduino with low dissipation (no heatsink). You need to check the MOSFET will work with logic level (5V) gate input.

what if you used RGB led modules instead of cutting and soldering pieces of led strip? i have used them for motorcycle ground effects and they are quite bright i think you would be fine with one per cube and they come with wire on both ends so you wouldn't have to solder onto the strips http://www.usledsupply.com/shop/rgb-smd-led-modules.html 16x modules $3ea =$48 1x arduino to 12v PWM 3ch 4A/Ch RGB driver $25 1x 12v 4A power supply $20 some pieces of 22-4 wire $ cheap for less then $100 you could have everything you need