Get a TLC5940 LED controller chip and use the basic example program (which just happens to be a "Larson Scanner" - which is what they're called).

Introducing Stage Series LED lighting! Inspired by the needs of a professional rally driver, these light bars have been designed for maximum functionality, with compact size, custom-engineered TIR optics, and a useful beam pattern, all in a highly durable package.

You can also run 18 LEDs off the arduino, but you would need to run them at 10ma, instead of 20, which would be a bit dimmer. There are other options too, but it gets more complicated.

Hey there everyone, this is my first post. I signed up for these forums because after hours of going about the internet, i was royally confused with this. Im pretty new to arduinos, or any type of electronics for that matter (mechanics were more my thing). I am building an LED knight rider scanner for the hood scoop of my truck, just for fun. Im going to have a number of LEDs inside it, to scan back and forth when the arduino receives power. If i was just going to use 13 or less LEDs, i would just have the negative all connected to the ground, and simply have one LED hooked up to each pin. i plan to use at least 18 LEDs though. After searching through google i started reading about charliplexing, and i think that is how i will be able to get this done! So far, not having too much luck though. The LEDs do cycle in order! But... other LEDs come on too if anyone can help me solve this i will be very grateful!

Functional Patterns. All Stage Series beam pattern options were designed with optical simulation modeling, to shape the output in a highly-functional beam pattern. No matter what your auxiliary lighting needs are, there is a Stage Series optic for you!

its a lot of extra stuff to learn and build, but you get the benefit of PWM, so thats kinda cool, if you want that feature.

Hippynerd: I re-drew the schematic with the resistors inside, in series, and it would only use one LED and 1 resistor at a time.

I re-drew the schematic with the resistors inside, in series, and it would only use one LED and 1 resistor at a time. It seems to me that would also be true if the resistors were in parallel with the LED. It would seem to me that if you are going to put the resistor inside the LED, you would put it in series to limit current, but it would be fixed to a specific voltage. I dont understand why you would put it in parallel though.

Proven Reliability. Stage Series lighting has been tested for long-term operation from -40 to 185 degrees F, vibration, moisture intrusion, and corrosion. All of these tests are completed to SAE/DOT standards, just like factory components. They’ve also been put to the test on-road, and are in-use by dozens of rally and endurance racing teams for nighttime stages and laps.

Hippynerd: Charlieplexing is a great way to control a lot of LEDs, but using LEDs with built in resistors might be an issue, since you will be always using 2 resitors anytime you try to light an LED.

fungus: Get a TLC5940 LED controller chip and use the basic example program (which just happens to be a "Larson Scanner" - which is what they're called).

Hippynerd: I was quoting you when I had said that. You suggested that the resistors will be in parallel, you put the word will in italics to emphasize that correct?

Experience. After over a decade in business, Diode Dynamics is one of the most trusted names in automotive LED lighting. We directly assemble and engineer our own products in the United States, allowing for higher quality and performance, with the newest and brightest LED technology. No matter what you’re driving, we pride ourselves in offering only the best possible LED solutions. Please contact us if you’d like to discuss your lighting project!Features

Focused. The compact size doesn’t mean they’re short on power! Thanks to the high-intensity Lumileds LED chips, coupled with our U.S. patent pending total internal reflection (TIR) optic, the total intensity of the Stage Series is far higher than a standard, generic light bar using basic optics or reflectors. Standard optics lose light internally, and to glare, spreading a little bit of light in every direction. Instead, the TIR optic in the Stage Series collects all of the light from the LED, and directs it only where you need it, drastically reducing glare and improving total efficiency.

If properly wired, you should be able to control 20 LEDs from 5 pins with charlieplexing. You could also multiplex 25 with 10 pins easily enough.

The code for turning on an LED will always be one high, and one low. both high, or both low should not light anything, and reversing polarity will change which LED is lit.

Compact. The lightbar is based on a narrow-profile extruded housing, to allow fitment in small and tight areas. At less than 42mm tall, they’ll fit in many places a traditional dual-row light bar won’t, while cutting total weight as well. The heatsink design also drastically reduces wind noise, and does not whistle in the wind like many generic housings.

White or Amber. All Stage Series light bars are available in a cool white or amber color. The white is a 6000K color temperature, which is a true white output, without any blue. The amber is a brilliant deep yellow color, perfect for hazards or high contrast in poor weather.

I've considered this project for about 20 years now, my car has a fake hood scoop that would be perfect for it. For some reason, i've never actually done it, I even have some boards that already do the circuit, all i would have to do is hook it up to new LEDs, and power it. Maybe one day I will do it...

Hippynerd: Charlieplexing is a great way to control a lot of LEDs, but using LEDs with built in resistors might be an issue, since you will be always using 2 resitors anytime you try to light an LED.

What i have right now: -Arduino Uno, with 6 LEDS (with build in resistors) the LEDs are connected like this: LED# | 1 | 2 | 3 | 4 | 5 | 6 pin13 | + | - | | | + | - pin12 | - | + | + | - | | pin11 | | | - | + | - | +

Hippynerd: I was quoting you when I had said that. You suggested that the resistors will be in parallel, you put the word will in italics to emphasize that correct?

I did read the first post? but i re-read it to see why you asked that, and saw that i forgot to use the code tag in my original post, sorry about that!

The chip makes sure all your LEDs are running at optimal power and protects your Arduino from the stress of charlieplexing.

Change it up. Each lightbar is based on 6-inch segments. Each segment is sealed with an individual lens and a double-wall seal. This makes them more weather tight than a large, single seal, and it also allows you to change up the outer lens to suit your needs. With just a few screws, you can replace the outer lens with a new one to change the beam pattern or color.

Thanks for the quick reply! ive been wanting to do this forever, and since im stuck at home sick, i thought id give it a shot! i updated the original post with more info!

Any help would be greatly appreciated! im having a blast playing around with the Arduino Uno and hope to be able to get this project running soon!

That leads me to believe that you know that the LEDs are in parallel (like thats how they always do it), I've never used those kinds of LEDs, but I would imagine the resistor would be series.

The chip makes sure all your LEDs are running at optimal power and protects your Arduino from the stress of charlieplexing.

If you use the TLC chip, you will only be able to run 16 per chip, and you will also need some other parts (a couple resistors and a cap per chip). If you want to run 18 LEDs, then you will need 2 TLCs, 4 resistors, and 2 or maybe 4 caps. You will also probably want to use some kind of circuit board to hold all these parts.

Hippynerd: Charlieplexing is a great way to control a lot of LEDs, but using LEDs with built in resistors might be an issue, since you will be always using 2 resitors anytime you try to light an LED.

Not just off road. In six-inch size, when installed as a pair and aimed in accordance with your state’s regulations, the Driving pattern meets SAE J581 as a Driving/Auxiliary High Beam Light, and the Wide pattern meets SAE J583 as a Foglamp, for legal on-road use. Please check your local laws and regulations for aiming, installation, and applicability.

another way to do it is to serialize each LED with its own chip. It uses a lot of parts, but its easy to expand/contract the number of LEDS.

Charlieplexing is a great way to control a lot of LEDs, but using LEDs with built in resistors might be an issue, since you will be always using 2 resitors anytime you try to light an LED. If you can control the resistor size, you can calculate your resistor size, and then use 2 resistors that are 1/2 the correct value, to end up with the right value when charlieplexed.

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Simple connections. All Stage Series LED lighting products use a standard DT type Deutsch-style connector, and come with a 6-inch pigtail, with bare leads. You can wire yourself, use an off-the-shelf Deutsch wire harness, or select an optional Diode Dynamics wire harness.

I was quoting you when I had said that. You suggested that the resistors will be in parallel, you put the word will in italics to emphasize that correct?