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Want to jazz up that acrylic sign with the RGB LED strips?

I have been watching the projects that make lighted signs with acrylic and RGB LED strips. Lot’s of red, green and blue signs.

Want to have a different color? Maybe jazz it up a little with flashing lights? Change color on the fly?

Here’s a way to use that Arduino that’s gathering dust in your shop after you upgraded to the X-controller.

It just takes a few hardware components and a little Arduino programming to liven up that sign you just made.

First a few notes about the circuitry. I am assuming an RGB LED strip that takes +12 VDC on one connection, then you turn the LEDs on by grounding the appropriate connection (ground blue to get the blue LEDs to turn on, etc.).

Also, take note that the maximum current for the transistors used is 200mA. My LEDs draw about 5mA each, so each transistor can drive a maximum 40 LEDs. To be conservative, with a 300 LED per 5 meter stip, this circuit would drive about 0.5 meters. If you are using a strip that is 150 LEDS per 5 meters then you could drive about 1 meter of that strip. If you need to drive a longer strip then you will have to upgrade the NPN transistors to a unit that can handle more current.

Programming the Arduino is not difficult. The easy way to do it is to use the Arduino PWM pins to vary the intensity of each color of LED. Using the PWM pins you can use various combinations to get a multitude of colors and you don’t have to bit bang a port to get PWM.

Here is an example of a simple program:

/**********************************************************************

  • Program to exercise an RGB LED strip without controller chip.
    *********************************************************************/

#define RGB_Red 9
#define RGB_Green 10
#define RGB_Blue 11

void setup()
{
pinMode(RGB_Red, OUTPUT);
pinMode(RGB_Green, OUTPUT);
pinMode(RGB_Blue, OUTPUT);

} /* setup */

void loop()
{
/* turn all the LEDs off */
analogWrite(RGB_Red, 0);
analogWrite(RGB_Green, 0);
analogWrite(RGB_Blue, 0);

/* turn all the LEDs on half intensity */
analogWrite(RGB_Red, 128);
analogWrite(RGB_Green, 128);
analogWrite(RGB_Blue, 128);

/* turn all the LEDs on full intensity */
analogWrite(RGB_Red, 255);
analogWrite(RGB_Green, 255);
analogWrite(RGB_Blue, 255);

} /* loop */

And here is the hardware:

8 Likes

Thanks @LarryM. Bookmarked for future reference.

You could use the programmable LED strips.
There is a lot of information on them.
You can get a lot of different patterns and different colored patterns out of them.

I have some of those too. The LED strips with controller chips embedded can be expensive, depending on where you buy them (I’ve seen $25 to $82 USD for a 5 meter strip). You can also program them with the Arduino, but it is slightly more complicated.

? expensive ?
http://www.ebay.com/itm/like/172232925768?lpid=82&chn=ps&ul_noapp=true

Do a search and you can get them really cheap!
You can hook them in series to make a longer strip if you need to.

@StephenCook

I had some time to kill and I looked at many of the offers on ebay and found that most of them are bait and switch sites. They list low prices for the search engines, but when you go to the product page you find that the low cost items are not what they described.

The strip that I’m working with now is 5 meters with 30 LEDs/meter and it is addressable, but not individually. You can only address the strip in groups of three LEDs. (Here’s an ordering tip: if the offer says you can cut the strip every three LEDs then it is not individually addressable, but addressable three LEDs at a time)

If you use the configuration menus on the ebay pages to match that set of characteristics then the price jumps to about $18 USD per 5 meter strip in China. This strip is about $30 USD in the US.

If you go to fully addressable and 60 LEDs/meter the price jumps to about $36 USD per strip in China. This strip goes from between $50 USD per strip and $82 USD per strip in the US.

That puts me back to where I think the addressable LED strips are pricey and you have to be very careful when ordering (even in the US) to make sure that you are going to get what you think you are ordering.

I think the sign community could get a lot of benefit from the unintelligent RGB strips with about $6 to $15 in control electronics that would differentiate their product from the standard three color choice with the less expensive LED strips.

Since I don’t sell these signs, my opinions here are most likely, totally wrong.

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You can make some really cool effects with the addressable strips, but like everyone’s mentioned you need to be comfortable jumping into some code. There are some controllers that have pre-programmed animations that you can switch through with an IR remote which can be neat, but if you’re looking for something specific messing around with code on an Arduino or something similar will be necessary.

If you’re thinking about diving in Adafruit has a real good primer on addressable LEDs (https://learn.adafruit.com/adafruit-neopixel-uberguide/overview). Their ‘house’ brand of addressable LEDs are called NeoPixels, but if you’re going to try and source them through aliexpress, alibaba, or ebay then you’ll want to search for the keyword “WS2812B” They’re the same thing.

I get mine from amazon for less than 10 bucks a 16ft roll

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