Hello. I’m new to the forum. Just found it yesterday. I live in the US in Utah. So far I’ve learned a bunch, but I still have many questions.
I work in Movie and TV productions building props and scenery. In an upcoming project I need a Police car light bar. I’ve already figured out how to construct the actual light bar itself and I’m pretty sure I know how I’m going to mount all the LED’s. I’m thinking of using RGB LED strips and running them 3 row high along the entire length front and back. Unless you know of a better option. I’ll be using standard 5mm White LED’s as well on both ends as alley lights. After doing much research though, I still don’t know which LED’s will give me the brightness I need. They need to show up bright in daylight as well as night. Then I need to program in a few different flash patterns that I can change by pushing a single button. At leased 3 for the front and 3 for the back. Something similar to the light bar in the video linked below.
I’m not asking for anyone to write the code for me. I just need some direction on how to get this done and make it act like a real tight bar.
Take a look at the video and let me hear any feed back you can offer.
Thank you in advance.
Doug
Hi Douglas,
Cool project! I have a few suggestions. First off, you will need very bright LEDS. Police lights will use something like 3-4 Watt LEDs. For a little perspective, each LED on a NeoPixel strip is about 0.3 Watts. You would be able to see strips but they wouldn’t have the same effect that police lights have. There are RGB programable 3 Watt LEDs that Adafruit makes called “Pixie - 3W Chainable Smart LED Pixel”. You can program them just like a NeoPixel strip using an Arduino (this is well documented, tons of tutorials). The realistic problem is that they take a ton of power and are pretty expensive.
Power wouldn’t be a problem. I can add 2 more car batteries in the trunk and wire them in Series or Parallel for either 12 or 24 volts power. Expense is a major issue though. I need to do this with a $300.00 budget. That is for everything, not just the LED’s.
A standard Police light bar only uses 1 row of 3-4 Watt LED’s. I was planning on using 3 rows of LED strips to give me a little more light output. And, I was thinking about the 144 light per Meter strips. The light bar is about 40 inches long so 3 strips front and back would work out for length.
Using an Arduino raises another question. As I mentioned, I need to program 3 or 4 flash patterns for the front side and 3 for the back side. Will an Arduino do that and stay programed when power is shut down between takes or over night?
Hi Douglas,
Using a ton of dense LED strips will still be pretty bright. When you program an Arduino that code is run any time you power up the device, until you replace it with new code. So you can power it down and start it up again as much as you want with no effect on its behavior. You will need to provide 5V dc to your LED strips with enough amps to drive those LEDs. Providing 12V directly will destroy the LEDS.
So do you think running 3, 144 lights/m strips will be bright enough? I’m sure it won’t be as bright as a real light bar. The only place I’ve seen the strips is in YouTube videos.
So, the programing stays in the Arduino when it’s off. Good to know. Thank you.
What about programing different flash patterns on a single Arduino? Would I be able to switch between them easily? Say, a button push from inside the car? It’s not so important for the Red/Blue on the front. That flash pattern can even look a bit random as long as the two sides are in sync. However, there needs to be 3 different, distinct, “Traffic Alert” patterns for the Amber LED’s in the rear. I don’t know much at all about programing. I’m a prop builder. lol I can make you a fine looking light bar, but programing might take me a while to master. lol
Thank you for responding. Any advice or help is much appreciated.
Also. I’m planing on powering the lights and the Arduino separately. A Buck converter will drop the 12v to 5v safely. And I was going to try powering the LED strips from both ends so there’s no voltage drop. I’ve done this before with other lights on a single run using a couple of Diodes to prevent power feed back.
Hi Douglas,
Powering the lights that way should work just fine.
As far as programming, you can program many different patterns, changed by a button if you like.
You can find a very conclusive write-up on programming NeoPixel (or WS2812B) LED’s here:
