Ir Illuminator – Part One

On January 25, 2010, in Electronics, openFloor, by Vlad Cazan

The first goal of my project is to create an infrared illuminator from scratch to avoid buying a really expensive one online. The model that  I aiming to recreate is this one found at Super Circuits online for $79.00 USD | | This is very expensive but it does come prebuilt with a stand that would making mounting it a breeze. It features 100 IR led and can light an area 30 feet away. This would be the ideal setup for my project.

Infrared radiation is officially defined as electromagnetic radiation with a wavelength between 0.7 and 300 micrometres, which equates to a frequency range between approximately 1 and 430 THz. The important thing to remember is that the wavelength of this radiation is far longer then that of visible light, so humans cannot see this type of light. There are three categories of IR called IR-A, IR-B, and IR-C. The most common is IR-A and it is used in telecommunications such as fibber optics due to its low level of loss. Any wave between 750nm and 1400nm would fall in this category. This is the same type of IR I will be using for this project. On the packaging of the LED’s it states that these IR LED’s are 950nm which should be just perfect for the application.

Building an IR Illuminator from Scratch

There are a few things I need to think about when starting a project like this from scratch. One very important issue is obviously power. On the side is a picture of the LEDs I purchased from a local hobby electronics shop in Toronto called Creatroninc. They are located at 255 College Street, Toronto Ontario, the owner is extremely helpful so if you have any questions just go by and you will be amazing how nice the owner really is. Anyways… these LEDs model number LTE-4208 take up to 100mA max and will run on a strict 1.2V energy stream. While experimenting I noticed that if you power the LED with anything higher then about 1.5V the LED’s starts smoking and poof, it burns out. I will have to be very careful with both the current and voltage of my device.  I will also plan on plugging the illuminator to a power adaptor to avoid using batteries which can provide a less then standard voltage stream. Once batteries start losing their power, the voltage can change dramatically.

Converting 6V DC 1000mA to 1.2V

Using a standard AC adaptor I can simply convert the 120V AC 12W current down to 6V DC at 1000mA. This is pretty good as it will let me power tons of LEDs but 6V is way to high for the LEDs. The simplest way to convert lower power electricity is using a transistor.  I found that the LM317T IC Regulator could adjust power anywhere from 1.2 to 37V  at a max of 1.5A. This should be enough to down-convert the power from 6V to a useable 1.2 V. This picture explains what resistors to use in order to get your desired current.

Building the Circuit

I have wired up this example and it seems to be working very well. The only issue that seems to be occurring is that the transistor is getting extremely hot after it being on for more then 5 minutes. To try and fight this I have used a heat sink attached to the transistor to try and dissipate the heat more efficiently. When connecting more LED’s more current will be pulled so hopefully there will be even less heat.

Here is the wiring for all 36 IR LED’s which I will be soldering together very soon.

Part Two –>

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1 Response » to “Ir Illuminator – Part One”

  1. Amber says:

    Whoa, whoa, get out the way with that good ifonramtoin.

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